Infection through bacteremia leads to sympathetic overactivity and then to the atherosclerotic process

Research long suggested infection to be a cause or to promote atherosclerosis. This idea is supported by many reports and epidemiological studies (1).
However, main trials using antibiotics have failed to prove their protective effects in secondary prevention of coronary artery disease (2).
Periodontal disease, one of the most common chronic bacterial infection, may represent a favorable scenario to verify the connection of infection and atherosclerosis/cardiovascular disease.
The first researchers to indicate a relationship between oral infections and atherosclerosis were Mattila and colleagues. In their study published in 1989 they have identified periodontal disease as an independent predictor of elevated risk of myocardial infarction (3).
Several studies are suggesting an oral source for atherosclerotic plaque - associated bacteria with demonstration about the presence of viable periodontal pathogens in atherosclerotic plaques (4, 5, 6, 7). In this regard an interesting hypothesis was proposed in 2004 that periodontal infection may lead to brief episodes of bacteremia with inoculation of atherosclerotic plaque by periodontal pathogens such as Porphyromonas gingivalis, Actinobacillus actinomycetemcomitants and Tannerela forsythensis (8).
Related to the subject a recent review says that clinical procedures by dentists on the teeth and periodontal, along with the daily brush made by patients, produce a transient bacteremia, which may cause a secondary infection in a distant tissue or organ, including arteries. For the authors of this review it is evident that both endodontic surgical procedures and non-surgical instrumentation of root channels during endodontia can produce a transient bacteremia. Also, they have stressed that a tooth extraction causes bacteremia in 100% of times (9).
Coincidently to the present matter a study published last month revealed data from Medicaid patients showing that the risk of adverse vascular events sharply increases in the month following invasive dental treatment and then gradually returns to normal over six months (10).
However, an important information is generally left aside by investigators studying the connection between oral infection and atherosclerosis/cardiovascular disease. These investigators don’t take in consideration that the sympathetic nervous system is intensely activated during bacteremia. This was demonstrated by studies showing that the sympathetic tone rapidly increases after the experimental injection or infusion of bacteria and similarly during bacteremia in humans (11, 12, 13, 14).
Moreover, in a systematic review published in 2007 about 57 per cent of studies reviewed showed a positive relationship between stress/psychological factors and periodontal disease (15). These results are reinforced by a very recent study indicating that the sympathetic nervous system is involved in the development of periodontitis and that blockade of beta-receptors in periodontal tissue by a sympatholitic (propranolol) inhibited osteoclast differentiation and prevented alveolar bone loss induced by Porphyromonas gingivalis (16)
In the acidity theory of atherosclerosis point of view the sympathetic predominance is the primary factor in the cascade of events leading to the atherogenic spiraling.
Therefore, we think infection through bacteremia can be added to the long list of risk factors for atherosclerosis/cardiovascular disease, as mentioned in the acidity theory paper and in other previous articles published in this blog (17).
Carlos Monteiro
1. Epstein SE, Zhou YF, Zhu J. Infection and atherosclerosis. Emerging mechanistic
paradigms. Circulation 1999;100:20–8.
2. Anderson JL. Infection, antibiotics and atherothrombosis: end of the road or new beginnings?, N Eng J Med 2005;352:1706-1709
3. Mattila K, Nieminen MS, Valtonen VV, et al. Association between dental health and acute myocardial infarction. Br Med J 1989;298:779–82.
4. Haraszthy VI, Zambon JJ, Trevisan M, Zeid M, Genco RJ. Identification of
periodontal pathogens in atheromatous plaques. J Periodontol 71:1554–1560, 2000
5. Stelzel M, et al. Detection of Porphyromonas gingivalis DNA in aortic tissue by PCR. J Periodontol 73:868–870, 2002
6. Kozarov EV, Dorn BR, Shelburne CE, Dunn WA, Jr, Progulske-Fox A. Human atherosclerotic plaque contains viable invasive Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis. Arterioscler Thromb Vasc Biol 25:e17–e18, 2005
7. Gaetti-Jardim E, Jr, Marcelino SL, Feitosa AC, Romito GA, Avila-Campos MJ. Quantitative detection of periodontopathic bacteria in atherosclerotic plaques from coronary arteries. J Med Microbiol 58:1568–1575, 2009
8. Giacona MB, Papapanou PN, Lamster IB, Rong IL, D’Agati VD, Schmidt AM, and Lalla E. Porphyromonas gingivalis induces its uptake by human monocytes/macrophages and promotes foam cell formation in vitro. FEMS Microbiol Letter. 241, 95-101, 2004
9. Cotti E, Dessi C, Piras A, Mercuro G. Can a chronic dental infection be considered a cause of cardiovascular disease? A review of the literature. International Journal of Cardiology, 2010, doi 10.1016/j.ijcard.2010.08.011
10. Minassian C, D’Aiuto F, Hingoriani AD, Smeeth L. Invasive dental treatment and risk for vascular events. A self-controlled case series. Ann Intern Med 2010; 153:499-506
11. Palsson J, Ricksten SE, Delle M, Lundin S. Changes in renal sympathetic nerve activity during experimental septic and endotoxin shock in conscious rats. Circ Shock 1988; 24:13341.
12. Jones SB, Kovarik MF, Romano FD. Cardiac and splenic norepinephrine turnover during septic peritonitis. Am J Physiol 1986; 250:R8927.
13. Leinhardt DJ, Arnold J, Shipley KA, Mughal MM, Little RA, Irving MH. Plasma NE concentrations do not accurately reflect sympathetic nervous system activity in human sepsis. Am J Physiol 1993; 265:E2848.
14. Straub RH, Pongratz G, Weidler C, Linde HJ, Kirschning CJ, Glück T, Schölmerich J, Falk W. Ablation of the sympathetic nervous system decreases gram-negative and increases gram-positive bacterial dissemination: key roles for tumor necrosis factor/phagocytes and interleukin-4/lymphocytes. Infect Dis. 2005 Aug 15;192(4):560-72.
15. Daiane C. Peruzzo, Bruno B. Benatti, Glaucia M.B. Ambrosano, Getúlio R. Nogueira-Filho, Enilson A. Sallum, Márcio Z. Casati, and Francisco H. Nociti Jr. A Systematic Review of Stress and Psychological Factors as Possible Risk Factors for Periodontal Disease. Journal of Periodontology, August 2007, Vol. 78, No. 8, Pages 1491-1504
16. Okada Y, Hamada N, Kim Y, Takahashi Y, Sasaguri K, Ozono S, Sato S. Blockade of sympathetic b-receptors inhibits Porphyromonas gingivalis-induced alveolar bone loss in an experimental rat periodontitis model. Arch Oral Biol. 2010 Jul;55(7):502-8.
17. Carlos ETB Monteiro, Acidic environment evoked by chronic stress: A novel mechanism to explain atherogenesis. Available from Infarct Combat Project, January 28, 2008 at http://www.infarctcombat.org/AcidityTheory.pdf

Association of lipid abnormalities with lactate and coronary artery disease progression

Lactate as a screening test for coronary artery disease
The association of increased lipid levels with abnormal lactate metabolism may provide a useful screening test for the detection of coronary artery disease (1). In fact it was demonstrated that plasma lipid abnormalities and myocardial lactate production at the time of the initial study were significantly associated with subsequent arteriographic progression (2).
In our opinion the raise in plasma lipids presented in these studies might be a response to injury of the arterial endothelium due to an increased release of lactate. The response to injury concept is supported by the acidity theory of atherosclerosis (4)
Lactate and severity of coronary artery disease
The amount of lactate released by the myocardium has been shown to be related to the severity of coronary artery disease (1,2,3). One of these studies (3) have shown heterogeneity of myocardial lactate metabolism at rest in patients with coronary-myocardial disease. Lactate was released or produced by the myocardium when there was no clinical evidence of ischemia and the chemical arterial-coronary sinus lactate difference showing net global lactate extraction (3).
Carlos Monteiro
1. G. Jackson, Lynne Atkinson, M. Clark, B. Crook, P. Armstrong, and S. Oram, Diagnosis of coronary artery disease by estimation of coronary sinus lactate. British Heart Journal, 1978, 40, 979-983 Full free text at http://www.ncbi.nlm.nih.gov/pmc/articles/PMC483520/
2. Bemis CE, Gorlin R, et al. Progression of coronary artery disease: A clinical arteriographic study. Circulation, Vol XLVII, March 1973. Full free text at http://circ.ahajournals.org/content/47/3/455.full.pdf
3. Gertz EW, Wisneski JA, Neese R, Bristow JD, Searle GL, Hanlon JT: Myocardial lactate metabolism: evidence of lactate release during net chemical extraction in man. Circulation 1981, 63: 1273-1279. Full free text at http://circ.ahajournals.org/cgi/reprint/63/6/1273
4. Carlos ETB Monteiro, Acidic environment evoked by chronic stress: A novel mechanism to explain atherogenesis. Available from Infarct Combat Project, January 28, 2008 at http://www.infarctcombat.org/AcidityTheory.pdf

Does serum lactic acid and lactate dehydrogenase (LDH) levels increase with age?

Loiseleur and Morel were the first to report in 1931 about an increase of serum lactic acid with age (1).
However, in a study by Gottfried, Pelz and Clifford published in 1961 it was observed no difference in serum lactic acid levels between a group of 49 men and women over 70 years of age and a control group under 50 years of age (2).
Also, Davis and colleagues in a study published in 1966 have reported that serum lactic acid does not increase with age. In two groups of ambulatory patients with average age of 67 years, totaling 544 subjects who were free of overt acute diseases, the regression analysis for both serum lactic acid and LDH not revealed any significant change (3).
Contrasting with the reports from Gottfried (2) and Davis (3), a study by Nagamine and Shima published in 1989 indicated from the serum chemical analysis, obtained from 1822 male and 1870 women outpatients, the values for LHD were higher in female over 50 years of age than in their counterpart. When male and female were combined the normal reference ranges for LDH tended to be elevated. The values for total cholesterol and triglyceride reached a peak at a certain age (4).
Taking in view the conflicting results in the above mentioned papers, we think that new investigations are warranted in order to definitively clarify if serum lactic acid and LDH are increased with ageing, if there is correlation with cholesterol levels, and about the potential of causal relations, as preached by the acidity theory of atherosclerosis (5).
Recalling O. J. Pollak, 1952:
“Certainly all tissues change with age. There is anatomic and chemical aging. The acidity of tissues increases with age; this favors the precipitation of cholesterol”
Carlos Monteiro
1. Loiséleur J and R Morel. Influence de l’age et de L’état fonctionnel du foie sur la lacticémie. C. R. Soc. Biol, Paris, 106:35-37, 1931
2. Gottfried S. P., K. S. Pelz and R. C. Clifford. Carbohydrate metabolism in healthy old men over 70 years of age. Amer J. med. Sci, 242: 475-480, 1961
3. Davis R. L., Lawton A. H. et al. Serum lactate and lactic dehydrogenase levels of aging males. J. Gerontology 1966, Oct 21(4):571-4
4. Nagamine Y, Shima K. Changes in normal reference ranges for serum chemical analyses with ageing. Nippon Ronen Igakkai Zasshi. 1989 Jan;26(1):31-6.
5. Carlos ETB Monteiro, Acidic environment evoked by chronic stress: A novel mechanism to explain atherogenesis. Available from Infarct Combat Project, January 28, 2008 at http://www.infarctcombat.org/AcidityTheory.pdf

Migraine, cardiovascular disease and higher lactic acid concentration in plasma

People with migraine, particularly those with aura (temporary visual or sensory disturbances before or during a migraine headache) , are at increased risk of death from coronary heart disease and stroke, according to research published this week on the the British Medical Journal. The study assessed the impact of mid-life migraine episodes in 18,725 men and women born between 1907 and 1935 who took part in the Reykjavik Study (set up in 1967 by the Icelandic Heart Association to study heart disease in Iceland). In total the research team explored over 470,000 person-years of data with a follow-up of 26 years. Their conclusion was that migraine with aura is an independent risk factor for cardiovascular and all cause mortality in men and women(1).
Interesting is that migraine suffers have higher lactic acid concentration in plasma (2), a decisive risk factor for cardiovascular disease, according to the acidity theory of atherosclerosis (3).
Carlos Monteiro
1.Larus S Gudmundsson, Ann I Scher, Thor Aspelund, Jon H Eliasson, Magnus Johannsson,Gudmundur Thorgeirsson, Lenore Launer and Vilmundur Gudnason. Migraine with aura and risk of cardiovascular and all cause mortality in men and women: prospective cohort study. Published 24 August 2010, doi:10.1136/bmj.c3966, BMJ 2010;341:c3966. Full free text at http://www.bmj.com/cgi/content/full/341/aug24_1/c3966
2.Okada H, Araga S, Takeshima T, Nakashima K. Plasma lactic acid and pyruvic acid levels in migraine and tension-type headache. Headache. 1998 Jan;38(1):39-42.
3.Carlos ETB Monteiro, Acidic environment evoked by chronic stress: A novel mechanism to explain atherogenesis. Available from Infarct Combat Project, January 28, 2008 at http://www.infarctcombat.org/AcidityTheory.pdf

Slow breathing increases baroreflex sensitivity and reduces sympathetic activity with beneficial effects on cardiovascular disease

Control breathing have been used as an effective strategy to calm down during stressful situations in daily life during centuries. The usual advice to “take a deep breath” under emotion circumstances such as stress, anxiety and anger is a clear indication of this, yet we do not normally stop to consider the connection between our breathing and emotional states. There is a study realized in Japan where two hundred and forty-one male and female undergraduates completed the questionnaire concerning stressful events in the real life and relaxation strategies they used to overcome these stressful events. The result clearly showed that the most numerous relaxation strategy was deep breathing. About 60% of subjects reported that they control breathing to calm down in their stressful situation. Many subjects have answered this question telling that abdominal breathing technique (diaphragmatic) was an effective strategy to calm down (1).
Relaxation through slower breaths ( fewer than 10 cycles per minute) , used in relaxation techniques like yoga and meditation, have been thought for a long time to have positive effects in the reduction of blood pressure.
Basic studies which support these empirical and clinical observations and looking to clarify the relationship between relaxation and respiratory functions, were started in the 1970s. A paper published in 1996 in Psychosomatic Medicine have referenced many of these basic studies in discussing about the therapeutic usages of the slowed respiration maneuver in attenuating the cardiac autonomic responses in patients with anxiety disorder (2).
However, despite the many clinical observations suggesting this direction, the medical science in general, particularly in cardiology, have overlooked about the influence of breathing and its relationship with the autonomic nervous system and the heart in weighing cardiac risk factors.
Fortunately, recent studies are shedding more light and evidences to the subject giving new grounds for the scientific establishment regarding the link breathing/emotional states. Their findings show that sympathetic activation and parasympathetic withdrawal is implicated in the pathogenesis of hypertension, obstructive sleep apnea, and congestive heart failure and that respiration contributes importantly to the decrease of sympathetic hyperactivity and the improvement of baroreflex sensitivity (3 - 13).
It is interesting to notice what Dr. William Davis, cardiologist and author of “The Heart Scan Blog”, said recently in an invited response to the article by Jimmy Moore “A Reader Asks ‘Does Acidic Blood Lead To Arterial Inflammation?’ Let’s Ask The Low-Carb Experts (14): “One final thought: Interestingly, the easiest and fastest way to increase the alkaline state of the blood is to breathe deeply. Deep breathing results in lower carbon dioxide in the blood, resulting in net alkalinization. Wouldn’t it be neat if we could study and quantify this response over time and its effects on atherosclerotic disease?”
Also interesting is that while some studies have documented greater total muscle sympathetic nerve activity (MSNA) during hypercapnia compared with hypoxia, other studies observed a higher MSNA response to hypoxia compared with hypercapnia in participants with slow and fast spontaneous breathing rates. Whereas the authors were unable to distinguish between chemo reflex, respiratory or cardiovascular induced activation their data suggest that hypercapnia and hypoxia cause distinct patterns of activation within regions normally associated with sympathetic control (15, 16).
Taking in view that continuous positive airway pressure treatment may reverse early signs of atherosclerosis (17) we think the slow breathing practice may also contribute for the prevention or regression of atherosclerosis, by reducing the sympathetic hyperactivity, be it stimulated by hypercapnia, hypoxia or other factors, according to the acidity theory concept (18, 19).
Moreover, hypertension is an important risk factor for the development of atherosclerosis, with these processes sharing some common mechanisms. The endothelium is usually placed as a probable central focus for the effects in both diseases, with evidences leading to the postulation that hypertension predispose and accelerate atherosclerosis (20).
Carlos Monteiro
Remarks:
Transcendental Meditation not only lowers colesterol (21) and blood pressure (22, 23) but also reduce atherosclerosis (18). Most interesting is that a meta-analysis of 31 studies found that TM produces a lowering of plasma lactate (24, 25). Lower plasma lactate indicates profound relaxation, since high concentrations of lactate have been associated with stress situations (for example high anxiety), and high blood pressure (20). More data about lactate, stress, hypertension and reduction of atherosclerosis on patients submitted to Ioga or TM at the acidity theory of atherosclerosis article (18).
1. Yutaka Haruki, I Homma, Akio Umezawa, Y Hasaoka. Facilitation and Emotion of Breathing During Changes in Emotion, Chapter by Akio Umezawa, Book Respiration and Emotion, Springer, 2001
2. Sakakibara M and Hayano J. Effect of Slowed Respiration on Cardiac Parasympathetic Response to Threat. Psychosomatic Medicine 58:32-37 (1996). Full free text at http://www.psychosomaticmedicine.org/cgi/reprint/58/1/32.pdf
3. Clark ME, Hirschman R., Effects of paced respiration on anxiety reduction in a clinical population, Biofeedback Self Regul. 1990 Sep;15(3):273-84.
4. Meles E, Giannattasio C, et al. Nonpharmacologic treatment of hypertension by respiratory exercise in the home setting, Am J Hypertens. 2004 Apr;17(4):370-4
5. Grossman E, Grossman A, et al. Breathing-control lowers blood pressure, Hum Hypertens. 2001 Apr;15(4):263-9.
6. Viskoper R, Shapira I et al. Nonpharmacologic treatment of resistant hypertensives by device-guided slow breathing exercises. Am J Hypertens. 2003 Jun;16(6):484-7.
7. Schein MH, Gavish B, et al. Treating hypertension with a device that slows and regularises breathing: a randomised, double-blind controlled study, J Hum Hypertens. 2001 Apr;15(4):271-8.
8. Elliot WJ, Izzo JL Jr, et al. Graded blood pressure reduction in hypertensive outpatients associated with use of a device to assist with slow breathing. J Clin Hypertens (Greenwich). 2004 Oct;6(10):553-9; quiz 560-1.
9. Oneda B, Ortega KC et al. Sympathetic nerve activity is decreased during device-guided slow breathing, Hypertension Research 33, 708-712 (July 2010) | doi:10.1038/hr.2010.74
10. Anderson DE, McNeely JD, Windham BG. Regular slow-breathing exercise effects on blood pressure and breathing patterns at rest, J Hum Hypertens. 2010 Mar 4. [Epub ahead of print]
11. Joseph CN, Porta C, et al. Slow Breathing Improves Arterial Baroreflex Sensitivity and Decreases Blood Pressure in Essential Hypertension, Hypertension 2005;46;714-718; originally published online Aug 29, 2005
12. Narkiewicz K et al. Sympathetic Neural Outflow and Chemoreflex Sensitivity Are Related to Spontaneous Breathing Rate in Normal Men. Hypertension 2006;47;51-55; originally published online Dec 12, 2005
13. Bernardi L, Porta C, Slow Breathing Increases Arterial Baroreflex Sensitivity in Patients With Chronic Heart Failure, Circulation 2002;105;143-145
14. Jimmy Moore “A Reader Asks ‘Does Acidic Blood Lead To Arterial Inflammation?’ Let’s Ask The Low-Carb Experts!”, published at http://livinlavidalowcarb.com/blog/?p=7270, in February 10, 2010:
15. Bernardi L, Gabutti A et al. Slow breathing reduces chemoreflex response to hypoxia and hypercapnia, and increases baroreflex sensitivity, Journal of Hypertension, V 19;I 12 - pp 2221-2229, 2001
16. Steinback C. et al. Hypercapnic vs. hypoxic control of cardiovascular, cardiovagal and sympathetic function, Am J Physiol Regul Integr Comp Physiol 296: R402-R410, 2009
17. Drager LF, Bortolotto LA, Figueiredo AC, Krieger EM, Lorenzi-Filho G. Effects of continuous positive airway pressure on early signs of atherosclerosis in obstructive sleep apnea. Am J Respir Crit Care Med 2007; 176: 706–712.
18. Carlos ETB Monteiro, Acidic environment evoked by chronic stress: A novel mechanism to explain atherogenesis. Available from Infarct Combat Project, January 28, 2008 at http://www.infarctcombat.org/AcidityTheory.pdf
19. Sympathetic predominance: a primary factor in the cascade of events leading to the atherogenic spiraling, Carlos Monteiro, Monday, February 22, 2010 at http://aciditytheory.blogspot.com/2010/02/sympathetic-predominance-primary-factor.html
20. Hypertension, atherosclerosis, stress and lactic acid, Carlos Monteiro,
Friday, November 27, 2009 at http://aciditytheory.blogspot.com/2009/11/hypertension-atherosclerosis-stress-and.html
21. Cooper M, Aygen M. Transcendental Meditation in the management of hypercholesterolemia, Journal of Human Stress 1979; 5:24-27
22. Schneider RH, Staggers F, Alexander C, et al. A randomized controlled trial of stress reduction for hypertension in older African Americans. Hypertension 1995; 26: 820-827
23. Alexander C, Schneider RH, Staggers F. A trial of stress reduction for hypertension in older African Americans (part II); sex and risk factor subgroup analysis, Hypertension 1996; 28:228-237
24. Michael C. Dillbeck, David W Orme-Johnson. Physiological differences between meditation and rest. American Psychologist, Vol 42(9), Sep 1987, 879-881
25. The Effects of the Transcendental Meditation Technique on Common Risk Factors and Overall Health. Adapted from Chalmers, R. Scientific Research on Maharishi's Vedic Approach to Health: Part I Transcendental Meditation Introduction and Overview of Research, January 1998, at http://www.tm.cme.edu/article.pdf

Obstructive sleep apnea: Intermittent hypoxia leads to sympathetic overactivity and then to atherosclerotic process

Obstructive sleep apnea (OSA) syndrome is caused by upper airway collapse during inspiration, causing intermittent hypoxemia, hypercapnia, acidosis, sympathetic nervous system activation, and arousal from sleep.
Mounting evidence shows that OSA is a risk factor for cardiovascular disease which is supported by epidemiological association studies. Longitudinal cohort studies also provide evidence that patients with untreated severe sleep apnea have an increased rate of cardiovascular events. The prevalence of coronary artery disease (CAD) is 3 to 5 times higher in patients with OSA compared with control populations (1, 2, 3, 4, 5, 6, 7).
Atherosclerosis is recognized as the precursor stage of coronary-myocardial disease.
A very recent paper published in Circulation Journal (8), by far the largest study to date, has showed that moderate to severe obstructive sleep apnea increases the risk of coronary heart disease or death by 68% in men under the age of 70, but does not increase the risk for men over 70 or for women. A total of 1927 men and 2495 women 40 years of age and free of coronary heart disease and heart failure at the time of baseline polysomnography were followed up for a median of 8.7 years in this prospective longitudinal epidemiological study.
Increased carotid intima-media thickness (IMT) and plaque occurrence was reported in OSA patients without any other significant co-morbidity compared to matched controls (9, 10, 11, 12).
The prevalence of hypertension is very high and the incidence of hypertension increases as the number of apneic and hypopneic events per hour rises. The association of OSA and hypertension has additive effects on the development of atherosclerosis. Daytime hypertension develops secondary to the persistently elevated sympathetic state (13). In a recent study of 94 middle-aged patients, the intima-media thickness of carotid artery was positively related to systolic blood pressure and apnea-hypopnea index (14).
Pathophysiological mechanisms linking OSA to atherosclerosis
OSA patients experience intermittent hypoxaemia and CO2 retention that modify the autonomic and haemodynamic responses to sleep (15). Indeed, chronic intermittent hypoxia may lead to sympathetic overactivity (16, 17). A study has shown that with mild apneic events (duration < 20 seconds), pretreatment with 100% oxygen effectively eliminated most of the increase in sympathetic nerve activity (25).
It is interesting to notice that continuous positive airway pressure treatment may reverse early signs of atherosclerosis (18).
There is increasing evidence that intermittent hypoxia is independently associated with dyslipidemia (19). In addition to clinical data, animal experiments also support a role of intermittent hypoxia in the pathogenesis of dyslipidaemia in sleep-disordered breathing (20, 21, 22).
The studies above mentioned confirm old experiments performed on rabbits where oxygen deficiency was attained by placing the animals daily into a chamber with decreased oxygen content (down to 12%) for 3–6 hours, for 4 months. It was shown that prolonged hypoxia brings about a high hypercholesterolemia and greatly intensifies the development of aortic and coronary atherosclerosis (26).
The demonstration that chronic intermittent hypoxia may lead to sympathetic overactivity and dyslipidemia adds more evidence to the acidity theory concept (23), with intermittent hypoxemia joining to other key factors for atherosclerosis, as discussed recently in this blog (24).
Carlos Monteiro
1. Levy P, Pepin JL, McNicholas WT. Should all sleep apnoea patients be treated? Yes. Sleep Med Rev 2002; 6:17–26.
2. Marin JM, Carrizo SJ, Vicente E, Agusti AG. Long-term cardiovascular outcomes in men with obstructive sleep apnoea–hypopnoea with or without treatment with continuous positive airway pressure: an observational study. Lancet 2005; 365: 1046–1053.
3. Pepperell JC, Ramdassingh-Dow S, Crosthwaite N, et al. Ambulatory blood pressure after therapeutic and sub therapeutic nasal continuous positive airway pressure for obstructive sleep apnoea: a randomised parallel trial. Lancet 2002; 359: 204–210.
4. Marin JM, Carrizo SJ, Vicente E, Agusti AG. Long-term cardiovascular outcomes in men with obstructive sleep apnoea-hypopnoea with or without treatment with continuous positive airway pressure: an observational study. Lancet. 2005;365:1046-1053.
5. Unruh ML, Enright PL, Polak JF, et al. The relationship of sleep apnea to carotid wall thickness among a large cohort of older adults. Sleep. 2005;20:A112.
6. Peker Y, Hedner J, Kraiczi H, Loth S. Respiratory disturbance index: an independent predictor of mortality in coronary artery disease. Am J Respir Crit Care Med. 2000;162:81-86.
7 Mooe T, Franklin KA, Holmstrom K, Rabben T, Wiklund U. Sleep-disordered breathing and coronary artery disease: long-term prognosis. Am J Respir Crit Care Med. 2001;164:1910-1913.
8. Daniel J. Gottlieb et al. Prospective Study of Obstructive Sleep Apnea and Incident Coronary Heart Disease and Heart Failure. The Sleep Heart Health Study. Circulation, Published online before print July 12, 2010
9. Drager LF, Bortolotto LA, Lorenzi MC, Figueiredo AC, Krieger EM, Lorenzi-Filho G. Early signs of atherosclerosis in obstructive sleep apnea. Am J Respir Crit Care Med 2005; 172: 613–618.
10. Baguet JP, Hammer L, Levy P, et al. The severity of oxygen desaturation is predictive of carotid wall thickening and plaque occurrence. Chest 2005; 128: 3407–3412.
11. Minoguchi K, Yokoe T, Tazaki T, et al. Increased carotid intima–media thickness and serum inflammatory markers in obstructive sleep apnea. Am J Respir Crit Care Med 2005; 172: 625–630.
12. Baguet JP, Hammer L, Levy P, Pierre H, Launois S, Mallion JMv, et al. The severity of oxygen desaturation is predictive of carotid wall thickening and plaque occurrence. Chest 2005; 128: 3407-12.
13. Narkiewicz K, Somers VK. Sympathetic nerve activity in obstructive sleep apnoea. Acta Physiol Scand. 2003;177:385-390
14. Drager LF, Bortolotto LA, Krieger EM, Lorenzi-Filho G. Additive effects of obstructive sleep apnea and hypertension on early markers of carotid atherosclerosis. Hypertension 2009; 53 : 64-9.
15. Somers VK, Dyken ME, Mark AL, Abboud FM. Sympathetic nerve activity during sleep in normal subjects. N Engl J Med 1993; 328 : 303-7.
16. Johnson, T. S., J. B. Young, and L. Landsberg. Sympathoadrenal responses to acute and chronic hypoxia in the rat. J. Clin. Invest. 71: 1263-1272, 1983.
17. Greenberg HE, Sica A, Batson D, Scharf SM. Chronic intermittent hypoxia increases sympathetic responsiveness to hypoxia and hypercapnia. J Appl Physiol 1999; 86: 298–305. Full free text at http://jap.physiology.org/cgi/content/full/86/1/298
18. Drager LF, Bortolotto LA, Figueiredo AC, Krieger EM, Lorenzi-Filho G. Effects of continuous positive airway pressure on early signs of atherosclerosis in obstructive sleep apnea. Am J Respir Crit Care Med 2007; 176: 706–712.
19. Drager, Luciano F; Jun, Jonathan; Polotsky, Vsevolod Y. Obstructive sleep apnea and dyslipidemia: implications for atherosclerosis. Curr Opin Endocrinol Diabetes Obes. 2010 Apr;17(2):161-5.
20. Li J, Grigoryev DN, Y e SQ, Thorne L, Schwartz AR, Smith PL, et al. Chronic intermittent hypoxia upregulates genes of lipid biosynthesis in obese mice. J Appl Physiol 2005; 99 :
1643-8.
21. Li J, Thorne LN, Punjabi NM, Sun CK, Schwartz AR, Smith PL, et al. Intermittent hypoxia induces hyperlipidemia in lean mice. Circ Res 2005; 97 : 698-706.
22. Li J, Savransky V, Nanayakkara A, Smith PL. O’Donnell CP, Polotsky VT. Hyperlipidemia and lipid peroxidation are dependent on the severity of chronic intermittent hypoxia. J Appl Physiol 2007; 102 : 557-63.
23. Carlos ETB Monteiro, Acidic environment evoked by chronic stress: A novel mechanism to explain atherogenesis. Available from Infarct Combat Project, January 28, 2008 at http://www.infarctcombat.org/AcidityTheory.pdf
24. Sympathetic predominance: a primary factor in the cascade of events leading to the atherogenic spiraling, Carlos Monteiro, Monday, February 22, 2010 at http://aciditytheory.blogspot.com/2010/02/sympathetic-predominance-primary-factor.html
25. Leuenberger U, Jacob E, Sweer L, Waravdekar N, Zwillich C, Sinoway L. Surges of muscle sympathetic activity during obstructive apnea are linked to hypoxemia. J Appl Physiol 1995;79:581– 8.
26. N. N. Kipshidze.The effect of oxygen deficiency on the development experimental atherosclerosis of the coronary arteries Bulletin of Experimental Biology and Medicine, Volume 47, Number 4, 447-453, 1958, DOI: 10.1007/BF00779624

Old experiments with rabbits and dogs provide powerful evidence for the Acidity Theory of Atherosclerosis (1)

Follows a summary about 2 studies from the beginning of the last century showing that acid-fed rabbits and dogs may develop atherosclerotic lesions:
1) Experiments from Oswald Loeb, a well-known professor in pharmacology and scientist from the University of Gottingen - Germany, have demonstrated in study published in 1913, that lactic acid-fed rabbits and dogs have resulted in atherosclerotic lesions in these animals (2). The book “Arteriosclerosis and hypertension, with chapters on blood pressure" (3), by Louis M Warfield, M. D. (Johns Hopkins), showed the following commentary about the experiments from Oswald Loeb:
“Oswald Loeb produced changes in the arteries of rabbits by feeding them sodium lactate (lactic acid). His controls fed on other acids became cachectic, but showed no arterial changes. He further found that in 100 gm. of human blood there was normally from 15 to 30 mg. of lactic acid. After heavy work, he found as much as 150 gm. He considers that after adrenalin or nicotin injections, the function of the liver is so disturbed that lactic acid is not bound. The arteriosclerosis is actually due to the presence of free lactic acid in the circulation. He succeeded, also, in producing lesions of the intima in a dog fed for a long time on protein poor diet, plus lactic acid and sodium lactate.”
2) I. Adler, M.D., from the Laboratories of the New York Board of Health, told in his paper entitled “Studies on Experimental Atherosclerosis” (4), published in 1913, that a casual remark by Dr. P. A. Levene have suggested the simple procedure of adding dilute hydrochloric acid to the dog's food and thus producing a chronic hyperacidity. This led Adler to include acid-fed dogs in his experiments. He told in his paper that though only two dogs have thus far been fed with hydrochloric acid, presenting sclerotic affections, the possibility can not be denied, especially in view of the numerous negative results with other methods, that these positive results are not mere coincidences, but are probably due to the hydrochloric acid. Referring at the end of his paper about the acid-fed dogs presenting atherosclerotic lesions he stated “that the work is being continued, and definite conclusions would at this stage be premature; but perhaps it may be permitted, even now, to venture the statement that in all probability the theory which bases atherosclerosis on a purely mechanical etiology will not prove tenable. Whether mechanical factors come into play at all, and if so, to what extent, remains to be seen. It seems almost certain, at least in our present state of knowledge, influences, subject possibly to more or less nerve control, are dominant factors in the etiology of atherosclerosis. Perhaps it may be discovered also that cholesterin and its various modifications and combinations, while undoubtedly an element of importance in atherosclerosis of the rabbit and human beings, may not be the sole predominant etiological factor.“. He finished telling that “If it should turn out that so simple a procedure as adding a certain proportion of hydrochloric acid to the food of dogs is sufficient to produce lesions of the blood vessels closely analogous, if not wholly identical with human atherosclerosis, a revision of our present theories will become necessary“.
Carlos Monteiro
1. Carlos ETB Monteiro, Acidic environment evoked by chronic stress: A novel mechanism to explain atherogenesis. Available from Infarct Combat Project, January 28, 2008 at http://www.infarctcombat.org/AcidityTheory.pdf
2. Loeb, O., Ueber experimentelle Arterienveraender ungen mit besonderer Beruecksichtigung der Wirkung der Milchsaeure auf Grund eigener Versuche, Deutsch. med. Wchnschr., 1913, xxxix, I819
3. Louis M Warfield, M. D., Third Edition, C. V. Mosby Company, 1920, with full free text at http://www.archive.org/stream/arteriosclerosis00warfuoft/arteriosclerosis00warfuoft_djvu.txt.
4. I. Adler, ‘Studies in Experimental atherosclerosis - A preliminary report’, The Journal of Experimental Medicine, 1913. Free full text at http://jem.rupress.org/content/20/2/93.full.pdf