Acute ethanol ingestion modifies the circulating plasma levels of atrial natriuretic peptide

Alcoholic cardiomyopathy : The result of dosage and individual predisposition

The individual amount of alcohol consumed acutely or chronically decides on harm or benefit to a person’s health. Available data suggest that one to two drinks in men and one drink in women will benefit the cardiovascular system over time, one drink being 17.6 ml 100 % alcohol. Moderate drinking can reduce the incidence and mortality of coronary artery disease, heart failure, diabetes, ischemic and hemorrhagic stroke. More than this amount can lead to alcoholic cardiomyopathy, which is defined as alcohol toxicity to the heart muscle itself by ethanol and its metabolites. Historical examples of interest are the Munich beer heart and the Tübingen wine heart. Associated with chronic alcohol abuse but having different etiologies are beriberi heart disease (vitamin B1 deficiency) and cardiac cirrhosis as hyperdynamic cardiomyopathies, arsenic poising in the Manchester beer epidemic, and cobalt intoxication in Quebec beer drinker’s disease. Chronic heavy alcohol abuse will also increase blood pressure and cause a downregulation of the immune system that could lead to increased susceptibility to infections, which in turn could add to the development of heart failure. Myocardial tissue analysis resembles idiopathic cardiomyopathy or chronic myocarditis. In the diagnostic work-up of alcoholic cardiomyopathy, the confirmation of alcohol abuse by carbohydrate deficient transferrin (CDT) and increased liver enzymes, and the involvement of the heart by markers of heart failure (e.g., NT-proBNP) and of necrosis (e.g., troponins or CKMb) is mandatory. Treatment of alcoholic cardiomyopathy consists of alcohol abstinence and heart failure medication.

Recurrent epidemic cholera with high mortality in Cameroon: persistent challenges 40 years into the seventh pandemic

Cameroon has experienced recurrent cholera epidemics with high mortality rates. In September 2009, epidemic cholera was detected in the Far North region of Cameroon and the reported case-fatality rate was 12%. We conducted village-, healthcare facility- and community-level surveys to investigate reasons for excess cholera mortality. Results of this investigation suggest that cholera patients who died were less likely to seek care, receive rehydration therapy and antibiotics at a healthcare facility, and tended to live further from healthcare facilities. Furthermore, use of oral rehydration salts at home was very low in both decedents and survivors. Despite the many challenges inherent to delivering care in Cameroon, practical measures could be taken to reduce cholera mortality in this region, including the timely provision of treatment supplies, training of healthcare workers, establishment of rehydration centres, and promotion of household water treatment and enhanced handwashing with soap.

Alcohol consumption and plasma atrial natriuretic peptide (from the HyperGEN study)

Although moderate alcohol consumption has been associated with a lower risk of cardiovascular disease, underlying physiologic mechanisms are not fully understood. Data relating alcohol intake to atrial natriuretic peptide (ANP) have been inconsistent. We evaluated whether alcohol consumption was associated with plasma ANP in 1,345 participants from the Hypertension Genetic Epidemiology Network (HyperGEN) study. We used random effect models to estimate the adjusted means of logarithmic transformed ANP. The mean age was 35.8 +/- 8.6 years, 91% were normotensive, 46% were men, and 40% and 60% were African-Americans and whites, respectively. In a model adjusting for age, body mass index, field center, education, gender, race, and serum albumin, alcohol consumption was positively associated with ANP in men (p < 0.0001 for trend) and women (p = 0.0014) and in African-Americans (p = 0.006) and whites (p < 0.0001). The adjusted mean of log-transformed ANP was 3.68, 3.67, 3.77, 3.76, 3.86, and 3.91 pg/ml in lifetime abstainers, former drinkers, and current drinkers of 1 to 6, 7 to 12, 13 to 24, and > 24 g/d, respectively. Controlling for additional factors, including left atrial size, ejection fraction, left ventricular mass, end-diastolic volume, systolic blood pressure, smoking, lipids, and serum creatinine did not change the results. Restriction to normotensive subjects yielded similar results. Alcohol intake was associated positively with systolic and diastolic blood pressure (p < 0.0001 each for trend). In conclusion, our data have shown a positive and linear association between alcohol consumption and ANP in men and women, irrespective of race.

The role of atrial natriuretic peptide in alcohol withdrawal: a peripheral indicator and central modulator?

Changes in fluid and electrolyte homeostasis may accompany and are likely to modify the clinical symptoms of alcohol-withdrawal reactions. It was of obvious theoretical and practical interest therefore to investigate the changes in the secretion of hormones, which regulate the fluid and electrolyte homeostasis (atrial natriuretic peptide, aldosterone and plasma renin activity) during alcohol withdrawal in chronic alcoholic patients. In a phase of severe withdrawal, there were increased plasma renin activity and aldosterone levels observed. In a phase of partial recovery, on the other hand, the elevated plasma renin activity and aldosterone levels were back to the normal range. In 60% of the patients, delirium tremens was gradually developing during the observation period. In these patients, an elevated level of atrial natriuretic peptide was observed at the time of hospital admission, i.e. days before the actual onset of delirium tremens. It is concluded that the disturbed volume homeostasis and the consequently altered plasma atrial natriuretic peptide secretion might be associated with, and therefore used as an indicator of the onset of delirium tremens. To study the role of central nervous atrial natriuretic peptide, mice were rendered tolerant to and dependent on alcohol with an alcohol-liquid diet for 14 days. Five hours after withdrawal from alcohol, withdrawal hyperexcitability symptoms were analyzed. Intracerebroventricular (i.c.v.) injection of atrial natriuretic peptide attenuated, whereas that of an antiserum against atrial natriuretic peptide intensified the severity of handling-induced convulsions. N-methyl-D-aspartate induced behavioral seizures in a dose-dependent manner, whose effect was more intensive during the alcohol-withdrawal period than in alcohol-naive animals. I.c.v. injections of atrial natriuretic peptide dose-dependently inhibited, whereas that of antiserum against atrial natriuretic peptide potentiated the seizure-inducing effect of N-methyl-D-aspartate in alcohol-dependent mice. Although tentatively, it is concluded that peripheral secretion of atrial natriuretic peptide may be an indicator, whereas central nervous atrial natriuretic peptide a neuropeptide modulator of alcohol-withdrawal symptomatology.

Atrial natriuretic peptide modulates N-methyl-D-aspartate-induced hyperexcitability in ethanol-dependent mice

The role of central nervous atrial natriuretic peptide was investigated for behavioral hyperexcitability in alcohol-dependent mice. Mice were made tolerant to and dependent on ethanol with an ethanol-liquid diet for 14 days. Five hours after withdrawal from ethanol, withdrawal symptoms were analyzed by scoring handling-induced convulsions. N-methyl-D-aspartate (NMDA) induced behavioral seizures in a dose-dependent manner, an effect which was more intensive during the ethanol withdrawal period than in alcohol-naive animals. Intracerebroventricular (i.c.v.) injections of alpha-atrial natriuretic peptide (atrial natriuretic peptide) dose-dependently inhibited, whereas injection of an antiserum against atrial natriuretic peptide potentiated, the seizure-inducing effect of NMDA in ethanol-dependent mice. The main conclusion is that central nervous atrial natriuretic peptide plays a modulatory role in behavioral hyperexcitability during alcohol withdrawal.

Changes in angiotensin II receptors in dopamine-rich regions of the mouse brain with age and ethanol consumption

The density of angiotensin II (Ang II) receptors was determined in three dopaminergic nerve terminal-rich brain regions (caudate putamen, nucleus accumbens, and ventral pallidum) of mice that were given either water (control) or 20% w/v ethanol (EtOH) to drink for either 2-8 weeks (young) or 46 weeks (old). The receptors were labeled with 125I-sarcosine1, isoleucine8 angiotensin II (125I-SI Ang II) and measured by quantitative densitometric image analysis (receptor autoradiography) or by saturation binding assays on homogenates of these brain regions. The selective AT2 receptor subtype antagonist PD 123319 (10 microM) was used to inhibit 125I-SI Ang II binding to AT2 receptors to determine AT1 receptor density in brain sections. In young control mice the density of Ang II receptor binding sites in the caudate putamen was 407+/-26 fmol/g, in the nucleus accumbens the density was 346+/-27 fmol/g, and in the ventral pallidum the density was 317+/-27 fmol/g. Less than 5% of specific 125I-SI Ang II binding was displaced by PD 123319, suggesting that nearly all of the Ang II receptors in these brain regions were the AT1 subtype. The Bmax in homogenates of these three regions in young control mice was 11.0+/-2.1 fmol/mg protein. The KD was 0.49+/-0.13. Ang II receptors in old mouse brains were decreased, respectively, by 32%, 35% and 30% in the caudate putamen, nucleus accumbens and ventral pallidum (p<0.001). Ang II receptors were slightly, but not significantly increased in both young and old EtOH-consuming mice.

Effect of chronic ethanol consumption on the atrial natriuretic system of spontaneously hypertensive rats

There is a lot of discussion on the effects of ethanol (ETOH) on blood pressure (BP). It has been suggested that chronic moderate ETOH consumption prevents the development of age-dependent hypertension in humans and spontaneously hypertensive rats (SHR). However, the mechanism mediating this effect is unknown. In the present studies, we hypothesized the implication of atrial natriuretic peptide (ANP), a BP-lowering hormone, on the antihypertensive effect of moderate ETOH consumption. A 20% v/v solution of alcohol was given as drinking fluid to SHR and normotensive Wistar-Kyoto (WKY) rats for up to 32 weeks. This treatment prevented, at least in part, the age-dependent increase of BP in SHR and WKY rats. The lower BP was associated with significantly lower levels of circulating atrial natriuretic peptide in both groups. After chronic ETOH administration, total ANP content and concentration were higher in the left and right atria of SHR and WKY rats than in water-treated controls. Despite the ETOH-induced increase in atrial ANP content, there was no significant change in atrial ANP mRNA, suggesting decreased atrial release. Chronic ETOH treatment significantly reduced ANP mRNA in the ventricles of SHR but not of WKY rats. Correspondingly, ventricular ANP content and concentration were lowered by ETOH in SHR only. Chronic ETOH administration induced a significant increase of plasma arginine vasopressin and a significant decrease of plasma aldosterone in SHR but not in WKY rats. Thus, chronic ETOH treatment prevented the age-dependent elevation of BP in both SHR and WKY rats and altered the activity of heart ANP as well as of the aldosterone and plasma arginine vasopressin systems.

Gene expression of A- and B-type natriuretic peptides in response to acute ethanol ingestion

Given that ethanol ingestion is associated with a disruption of water and electrolyte balance in addition to being a significant risk factor for cardiovascular disease, we have investigated the gene expression of ANP and BNP in response to acute doses of ethanol. Wistar rats were administered either a 5 g/kg dose of ethanol or an equivalent volume of water, and atrial and ventricular tissue samples were removed at 30, 60, and 120 min for analyses. Although no differences in ANP mRNA were observed between ethanol and water-treated rats during the time course, BNP mRNA levels in ethanol-treated rats were 43% of those present in water-treated animals in atrial tissue at 120 min. In ventricular tissue, BNP mRNA levels were reduced similarly to 38% of control. These results suggest a possible differential regulation of A- and B-type natriuretic peptides under the influence of ethanol ingestion.

Influence of alcohol on the hydromineral hormone responses to exercise in a warm environment

Alcohol consumption at rest is associated with disturbed water and salt regulation reflected by changed responses in the hydromineral hormones. This study investigated the effect of alcohol on endocrine systems involved in body fluid and electrolyte regulation under conditions of physical exercise in the heat, a situation in which under normal circumstances, the hydromineral hormones are stimulated in an attempt to preserve physiological homeostasis. Eight healthy male volunteers participated in two trials, which differed only in the presence or absence of alcohol (1.2 g alcohol.kg-1 body mass) in a cocktail drink. After consuming the cocktail, the subjects exercised for 60 min on a cycle ergometer (45% maximal oxygen consumption) at 35 degrees C. Compared to the control situation alcohol consumption (maximal plasma concentrations reaching about 1.08 g.l-1) produced an increase in body fluid loss (P < 0.05), but did not induce significant differences in plasma volume changes. Plasma volume decreased in both sessions during exercise (P < 0.01) and a significant rebound (P < 0.001) occurred during recovery. Osmolality was significantly higher (P < 0.001) during rest, exercise and recovery periods compared to the placebo trials, but no effect of alcohol on plasma Na+ and K+ concentrations was observed. In the alcohol test conditions, the arginine vasopressin (AVP) response to exercise was significantly dampened (P < 0.05). In contrast, alcohol had no effect on aldosterone or atrial natriuretic peptide (ANP). These results demonstrated that alcohol ingestion augmented body fluid losses due to a suppressive effect on AVP during physical exercise conducted in a warm environment. The increase in osmolality due to alcohol did not influence the aldosterone and ANP responses, which would suggest that total osmolality does not play a major role in the regulation of these hormones.

Dietary salt and voluntary ethanol consumption in golden hamsters

Adult male golden hamsters were maintained on powdered Purina chow and tap water, and were permitted continuous access to either a 15% or a 30% ethanol solution (v/v); after an initial 4-5 weeks of ethanol availability, hamsters had stabilized their intakes and were deriving an average of 1.25 and 1.96 g/day of absolute ethanol from the 15% and 30% solutions, respectively. When salt was added to the diet in increasing concentrations ranging from 4% to 10% over a period of 40 days, hamsters reduced chow-derived calories by up to 35%, increased tap water consumption by up to 50%, and increased consumption of ethanol solutions by up to 100%; when unadulterated Purina chow was reinstated, intakes of chow-derived calories, tap water, and ethanol solutions returned to baseline levels. Hamsters that were continuously maintained on unadulterated Purina chow, but with chow-derived calories matched to that of animals on the salt-adulterated diet, significantly increased their ethanol intake, but not their tap water intake; the increase in their ethanol intake was only about half as large as that of hamsters that had salt added to the diet, but the increase persisted even after ad lib feeding was reinstated. The results indicate that the addition of salt to the diet of hamsters produces large increases in ethanol consumption; furthermore, the increased ethanol intake is not simply the result either of a nonselective increase in fluid consumption or of the reduction in food intake that accompanies the addition of salt to the diet. Results are related to the possible role of the renin-angiotensin system in the control of ethanol consumption in the golden hamster.