The discovery of benzoxazine sulfonamide inhibitors of NaV1.7: Tools that bridge efficacy and target engagement.

The voltage-gated sodium channel NaV1.7 has received much attention from the scientific community due to compelling human genetic data linking gain- and loss-of-function mutations to pain phenotypes. Despite this genetic validation of NaV1.7 as a target for pain, high quality pharmacological tools facilitate further understanding of target biology, establishment of target coverage requirements and subsequent progression into the clinic. Within the sulfonamide class of inhibitors, reduced potency on rat NaV1.7 versus human NaV1.7 was observed, rendering in vivo rat pharmacology studies challenging. Herein, we report the discovery and optimization of novel benzoxazine sulfonamide inhibitors of human, rat and mouse NaV1.7 which enabled pharmacological assessment in traditional behavioral rodent models of pain and in turn, established a connection between formalin-induced pain and histamine-induced pruritus in mice. The latter represents a simple and efficient means of measuring target engagement.

Correction to "Sulfonamides as Selective NaV1.7 Inhibitors: Optimizing Potency and Pharmacokinetics to Enable in Vivo Target Engagement".

[This corrects the article DOI: 10.1021/acsmedchemlett.6b00243.].

Sulfonamides as Selective NaV1.7 Inhibitors: Optimizing Potency and Pharmacokinetics to Enable in Vivo Target Engagement.

Human genetic evidence has identified the voltage-gated sodium channel NaV1.7 as an attractive target for the treatment of pain. We initially identified naphthalene sulfonamide 3 as a potent and selective inhibitor of NaV1.7. Optimization to reduce biliary clearance by balancing hydrophilicity and hydrophobicity (Log D) while maintaining NaV1.7 potency led to the identification of quinazoline 16 (AM-2099). Compound 16 demonstrated a favorable pharmacokinetic profile in rat and dog and demonstrated dose-dependent reduction of histamine-induced scratching bouts in a mouse behavioral model following oral dosing.

The discovery and optimization of a novel class of potent, selective, and orally bioavailable anaplastic lymphoma kinase (ALK) inhibitors with potential utility for the treatment of cancer.

A class of 2-acyliminobenzimidazoles has been developed as potent and selective inhibitors of anaplastic lymphoma kinase (ALK). Structure based design facilitated the rapid development of structure-activity relationships (SAR) and the optimization of kinase selectivity. Introduction of an optimally placed polar substituent was key to solving issues of metabolic stability and led to the development of potent, selective, orally bioavailable ALK inhibitors. Compound 49 achieved substantial tumor regression in an NPM-ALK driven murine tumor xenograft model when dosed qd. Compounds 36 and 49 show favorable potency and PK characteristics in preclinical species indicative of suitability for further development.

Discovery and optimization of a potent and selective triazolopyridinone series of c-Met inhibitors.

Deregulation of the receptor tyrosine kinase c-Met has been implicated in several human cancers and is an attractive target for small molecule drug discovery. Herein, we report the discovery of a structurally diverse series of carbon-linked quinoline triazolopyridinones, which demonstrates nanomolar inhibition of c-Met kinase activity. This novel series of inhibitors exhibits favorable pharmacokinetics as well as potent inhibition of HGF-mediated c-Met phosphorylation in a mouse liver pharmacodynamic model.

Discovery and optimization of potent and selective triazolopyridazine series of c-Met inhibitors.

Deregulation of the receptor tyrosine kinase c-Met has been implicated in several human cancers and is an attractive target for small molecule drug discovery. We previously showed that O-linked triazolopyridazines can be potent inhibitors of c-Met. Herein, we report the discovery of a related series of N-linked triazolopyridazines which demonstrate nanomolar inhibition of c-Met kinase activity and display improved pharmacodynamic profiles. Specifically, the potent time-dependent inhibition of cytochrome P450 associated with the O-linked triazolopyridazines has been eliminated within this novel series of inhibitors. N-linked triazolopyridazine 24 exhibited favorable pharmacokinetics and displayed potent inhibition of HGF-mediated c-Met phosphorylation in a mouse liver PD model. Once-daily oral administration of 24 for 22days showed significant tumor growth inhibition in an NIH-3T3/TPR-Met xenograft mouse efficacy model.

Probiotic yogurt in the elderly with intestinal bacterial overgrowth: endotoxaemia and innate immune functions.

A study was conducted in healthy elderly living independently in senior housing to assess the impact of a probiotic yoghurt supplement on small intestinal bacterial overgrowth. Twenty-three participants with positive and thirteen participants with negative hydrogen breath test were studied before and after a period of 4 weeks of probiotic yoghurt administration. Intestinal permeability, plasma endotoxin levels, phagocytic activity of leucocytes, cytokine production by monocytes and free radical response of neutrophils were determined. Intestinal permeability was similar for the two groups and was unaffected by probiotic treatment. Both plasma endotoxin levels and the basal phagocytic activity of leucocytes decreased after yoghurt intake in the two groups. Exposure of monocytes and neutrophils ex vivo led to an increased cytokine response and free radical response, respectively. The normalisation of the various cytokine responses was more apparent in the group with positive breath test. In addition, the plasma levels of lipoplysaccharide binding protein and soluble CD14, lipoplysaccharide pattern recognition receptors and surrogate markers of lipoplysaccharide permeability were diminished by the end of the study. In conclusion, probiotic administration in the elderly normalises the response to endotoxin, and modulates activation markers in blood phagocytes, and therefore may help reduce low-grade chronic inflammation.

Alcohol, intestinal bacterial growth, intestinal permeability to endotoxin, and medical consequences: summary of a symposium.

This report is a summary of the symposium on Alcohol, Intestinal Bacterial Growth, Intestinal Permeability to Endotoxin, and Medical Consequences, organized by National Institute on Alcohol Abuse and Alcoholism, Office of Dietary Supplements, and National Institute of Diabetes and Digestive and Kidney Diseases of National Institutes of Health in Rockville, Maryland, October 11, 2006. Alcohol exposure can promote the growth of Gram-negative bacteria in the intestine, which may result in accumulation of endotoxin. In addition, alcohol metabolism by Gram-negative bacteria and intestinal epithelial cells can result in accumulation of acetaldehyde, which in turn can increase intestinal permeability to endotoxin by increasing tyrosine phosphorylation of tight junction and adherens junction proteins. Alcohol-induced generation of nitric oxide may also contribute to increased permeability to endotoxin by reacting with tubulin, which may cause damage to microtubule cytoskeleton and subsequent disruption of intestinal barrier function. Increased intestinal permeability can lead to increased transfer of endotoxin from the intestine to the liver and general circulation where endotoxin may trigger inflammatory changes in the liver and other organs. Alcohol may also increase intestinal permeability to peptidoglycan, which can initiate inflammatory response in liver and other organs. In addition, acute alcohol exposure may potentiate the effect of burn injury on intestinal bacterial growth and permeability. Decreasing the number of Gram-negative bacteria in the intestine can result in decreased production of endotoxin as well as acetaldehyde which is expected to decrease intestinal permeability to endotoxin. In addition, intestinal permeability may be preserved by administering epidermal growth factor, l-glutamine, oats supplementation, or zinc, thereby preventing the transfer of endotoxin to the general circulation. Thus reducing the number of intestinal Gram-negative bacteria and preserving intestinal permeability to endotoxin may attenuate alcoholic liver and other organ injuries.

Discovery and optimization of triazolopyridazines as potent and selective inhibitors of the c-Met kinase.

Tumorigenesis is a multistep process in which oncogenes play a key role in tumor formation, growth, and maintenance. MET was discovered as an oncogene that is activated by its ligand, hepatocyte growth factor. Deregulated signaling in the c-Met pathway has been observed in multiple tumor types. Herein we report the discovery of potent and selective triazolopyridazine small molecules that inhibit c-Met activity.

Is nutrient intake a gender-specific cause for enhanced susceptibility to alcohol-induced liver disease in women?

AIM: Women have a higher susceptibility to alcohol-induced liver disease (ALD) than men. Gender-related differences in food preference were described in previous studies for several populations, but not in alcohol abusers. As certain micronutrients are reported to take influence on the development of ALD in animal experiments, the hypothesis of the present retrospective cross-sectional study was that gender-dependent (micro-) nutrient intake in patients with ALD may cause the higher susceptibility of women to this disease. METHODS: In 210 patients (male: 158, female: 52) with different stages of ALD (ALD1: mild stage of liver damage; ALD2: moderately severe changes of the liver with signs of hepatic inflammation; ALD3: severely impaired liver function) and in 336 controls (male: 208, female: 128), nutrient intake was determined by a computer-guided diet history, and related to the severity of ALD in dependence on the sex of the patients. RESULTS: No significant differences between males and females with ALD were calculated for the intake (per kg body weight/day) of protein, carbohydrates, fat, and the intake (per kg body weight/day) of most micronutrients. In females with ALD, higher intake was found for vitamin C (ALD3), calcium (ALD2), iron (ALD1 and ALD2), and zinc (ALD1), but the consumption of none of these micronutrients seems to contribute to a higher susceptibility to ALD in females. CONCLUSION: Though the present study confirms the higher susceptibility to ALD in women, the data of calculated daily macro- and micronutrient intake do not suggest any explicit influence of gender-specific nutrition in the development of ALD.

Conjugated primary bile salts reduce permeability of endotoxin through intestinal epithelial cells and synergize with phosphatidylcholine in suppression of inflammatory cytokine production.

OBJECTIVE: Endotoxemia was shown to be integral in the pathophysiology of obstructive jaundice. In the current study, the role of conjugated primary bile salts (CPBS) and phosphatidylcholine on the permeability of endotoxin through a layer of intestinal epithelial cells and the consequent activation of basolaterally cocultured human mononuclear leukocytes were measured. DESIGN: In a coculture model, a layer of differentiated, confluent Caco-2 cells was apically stimulated with growth-arrested, nonpathogenic Escherichia coli. SETTING: Basic human cell culture laboratory. INTERVENTIONS: The effect of CPBS (0.5 mM and 1.5 mM), phosphatidylcholine (0.38 mM), and human bile (0.5% vol/vol) on the barrier function was assessed by the measurement of transepithelial electrical resistance, by endotoxin permeability through the intestinal epithelial cell layer, and by basolateral cytokine enzyme-linked immunosorbent assay measurement (tumor necrosis factor-[alpha], interleukins-6, -8, and -10). Micelles formed by CPBS were detected by dynamic light scattering. The association of endotoxin with CPBS micelles was tested by fluorescence resonance energy transfer. MEASUREMENTS AND MAIN RESULTS: Apical addition of CPBS suppressed the permeability of endotoxins through the intestinal epithelial cell layer significantly. In parallel, apical supplementation of CPBS dose-dependently reduced the basolateral production of all cytokines measured. Apical phosphatidylcholine supplementation enhanced this effect significantly. CPBS formed micelles (diameter, 134 +/- 7 nm), which were able to bind endotoxin to their surface. CONCLUSIONS: CPBS can reduce the permeation of endotoxin through intestinal epithelial cell layers by binding it to micelles. Thereby, the inflammatory processes beyond the mucosal surface are suppressed, an effect that is enhanced by phosphatidylcholine.

Beyond HDL-cholesterol increase: phospholipid enrichment and shift from HDL3 to HDL2 in alcohol consumers.

The reduction of cardiovascular mortality associated with moderate alcohol consumption is chiefly thought to be mediated by an increase of high density lipoprotein cholesterol (HDL-CH). This study highlights additional qualitative changes of HDL that might augment this antiatherogenic effect. In 279 healthy men, alcohol and nutrient consumption were evaluated. Groups 1 (n=62), 2 (n=172), and 3 (n=45) comprised subjects with alcohol consumption of 0-5.0, 5.1-30.0, and 30.1-75 g/day, respectively. Lipid analysis was performed in nonfractionated and fractionated plasma, including subfractions HDL(2a), HDL(2b), and HDL(3). No difference in LDL-cholesterol was observed. Compared with group 1, groups 2 and 3 exhibited significant increases of HDL-CH (group 1, 44 +/- 10 mg/dl; group 2, 51 +/- 11 mg/dl; group 3, 55 +/- 11 mg/dl; mean +/- SD, P<0.0005), accompanied by enhanced lipidation of HDL (increase of the HDL(2)-CH/HDL(3)-CH ratio). Moreover, phospholipid enrichment of HDL occurred in alcohol consumers, whereas the ratios between other HDL components remained constant. Multivariate analysis revealed alcohol to have the foremost statistical influence on changes of the HDL fraction, followed by body mass index and physical activity level. The increased lipidation of HDL found in alcohol consumers might augment the antiatherogenic effect of HDL-CH increase. In addition, the phospholipid enrichment of HDL might reduce the inflammatory response of atherogenesis.

Arginine does not exacerbate markers of inflammation in cocultures of human enterocytes and leukocytes.

Enteral arginine supplementation in the critically ill has become a matter of controversy. In this study, we investigated effects of the addition of 0.4 and 1.2 mmol/L arginine in a coculture model on markers of inflammation, enterocyte layer integrity, and amino acid transport. In this model, a monolayer of intestinal epithelial cells (Caco-2) separated compartments with nonpathogenic Escherichia coli and mononuclear leukocytes. Activation of enterocytes and leukocytes was assessed by the measurement of nitric oxide, TNF-alpha, IL-6, IL-8, IL-10, and IFN-gamma. Further outcomes were the transepithelial flux of 22 amino acids, their catabolism, and the integrity of the enterocyte layer assessed as permeability of fluorescein dextran (M(r) 4400). Bacterial stimulation of intestinal epithelial cells enhanced the basolateral concentration of nitric oxide and all cytokines measured. Supplementation with arginine did not affect epithelial integrity, production of any of the cytokines investigated, or the amount of nitric oxide. The amino acid used primarily by nonstimulated intestinal epithelial cells cocultured with leukocytes was glutamine. Activation of IEC with bacteria significantly enhanced the catabolism of serine, asparagine, and lysine, and reduced glutamine catabolism. Addition of arginine increased ornithine formation and moderately reduced transepithelial transport of methionine and other amino acids. Hence, arginine supplementation does not interfere with inflammation-associated cross-talk between human enterocytes and leukocytes. Because it also does not seem to affect the integrity of enterocyte layers, a detrimental role of arginine during septic-like conditions seems unlikely.

Saturation of retinol-binding protein correlates closely to the severity of alcohol-induced liver disease.

Impaired metabolism of retinol has been shown to occur in alcohol-induced liver disease (ALD). The purpose of the present study was to investigate the saturation of retinol-binding protein (RBP) in 6 patients with different stages of ALD. Hospitalized alcohol consumers (n=118) with different stages of ALD (ALD1: mild stage of liver damage; ALD2: moderately severe changes of the liver with signs of hepatic inflammation; ALD3: severely impaired liver function) and 45 healthy control subjects were nutritionally assessed, and retinol and RBP content was measured in plasma by high-performance liquid chromatography and enzyme-linked immunosorbent assay methods, respectively. No differences were noted in daily retinol intake, but subjects with ALD had significantly lower concentrations of retinol in plasma (ALD1: 1.81+/-0.17 micromol/l [mean+/-S.E.M.]; ALD2: 1.95+/-0.24 micromol/l; ALD3: 0.67+/-0.13 micromol/l) compared to controls (2.76+/-0.19 micromol/l). Subjects of group ALD2 had significantly higher plasma RBP levels than controls (P<.05) and patients with ALD1 (P<.05) and ALD3 (P<.001). The relative saturation of RBP with retinol decreased with severity of ALD (controls: 76.8+/-5.0%; ALD1: 55.8+/-6.5%; ALD2: 43.5+/-6.2%; ALD3: 29.0+/-5.1%). The present study indicates that plasma concentrations of retinol and RBP per se do not correlate to severity of ALD, but rather that the retinol/RBP ratio links to the severity of alcohol-induced liver damage. From these results, a reduced availability of retinol in the periphery due to an altered saturation of RBP can be concluded.

Activation of the innate immune system and alcoholic liver disease: effects of ethanol per se or enhanced intestinal translocation of bacterial toxins induced by ethanol?

It is generally accepted that activation of the innate immune system and increased release of pro-inflammatory cytokines and other mediators plays an important role in the development of alcoholic liver disease (ALD). The mechanisms involved in the ethanol-induced activation of monocytes/macrophages (including Kupffer cells) are however, still a matter of debate. The brief review will summarize the published data from the literature on the two main pathomechanisms discussed until now: I) Gut-derived bacterial toxins, specially endotoxin; and II) metabolic changes induced by alcohol oxidation (independent of mechanism I). For pathomechanism I, clear evidence has been published from numerous groups: Alcohol induces mucosal injury in the upper gastrointestinal tract and leads to marked increase in the permeability of the gut mucosa to macromolecules such as endotoxin. The resulting endotoxemia then leads to activation of Kupffer cells and other macrophages. The increased release of pro-inflammatory mediators (e.g., TNF-alpha, Il-1, reacting oxygen species) and infiltration of other inflammatory cells (e.g., neutrophils) finally causes liver damage. Regarding the second pathomechanism it has repeatedly been argued that the metabolic alterations which are induced by chronic administration of ethanol to rats or mice might increase the sensitivity of monocytes/macrophages to secrete TNF-alpha and other pro-inflammatory mediators thereby increasing the susceptibility to ethanol-induced liver injury. However, in all feeding experiments the effect of ethanol on intestinal permeability and enhanced translocation of bacterial toxins (endotoxin) is likely to occur (or at least cannot be excluded). The latter holds true also for experiments using isolated macrophages/Kupffer cells from ethanol fed animals. Therefore, to clarify whether or not alterations related to ethanol metabolism ("direct" effects of ethanol) contribute to the activation of the innate immune system studies using germ-free animals are needed to exclude the "indirect" effect of ethanol via gut-derived bacterial toxins.

Decreased expression of cytochrome P450 protein in non-malignant colonic tissue of patients with colonic adenoma.

BACKGROUND: Cytochrome P450 (CYP) enzymes in epithelial cells lining the alimentary tract play an important role in both the elimination and activation of (pro-)carcinogens. To estimate the role of cytochrome P450 in carcinogenesis of the colon, expression patterns and protein levels of four representative CYPs (CYP2C, CYP2E1, CYP3A4 and CYP3A5) were determined in colon mucosa of normal and adenomatous colonic tissue of patients with adenomas and disease-free controls. METHODS: Expression of CYP2C, CYP2E1, CYP3A4, and CYP3A5 in colon mucosa of normal and adenomatous colonic tissue of patients with adenoma and disease-free controls was determined by RT-PCR. Protein concentration of CYPs was determined using Western blot. RESULTS: With the exception of CYP3A5, expression of CYP mRNA was similar among groups and tissues (e.g. normal colon mucosa and adenoma). CYP3A5 mRNA expression was significantly higher in adenoma in comparison to normal tissue of patients with adenoma (approximately 48%). When comparing protein concentrations of CYPs measured in adenomas with neighboring normal colonic mucosa no differences were found. However, in normal tissue of patients with adenomas, protein levels of CYP2C8, CYP3A4 and CYP3A5, but not that of CYP2E1, were significantly lower than in biopsies obtained from disease-free controls. Specifically, in normal colonic mucosa of patients protein concentrations of CYP2C8, CYP3A4, and CYP3A5 were approximately 86%, approximately 69%, and approximately 54%, respectively, lower than in disease-free controls. CONCLUSION: In conclusion, among other factors, the altered protein levels of certain CYPs (e.g. CYP2C8, CYP3A4 and CYP3A5) in colon mucosa might contribute to the development of neoplasia in the colon.

Distribution of cytochrome P450 2C, 2E1, 3A4, and 3A5 in human colon mucosa.

BACKGROUND: Despite the fact that the alimentary tract is part of the body's first line of defense against orally ingested xenobiotica, little is known about the distribution and expression of cytochrome P450 (CYP) enzymes in human colon. Therefore, expression and protein levels of four representative CYPs (CYP2C(8), CYP2E1, CYP3A4, and CYP3A5) were determined in human colon mucosa biopsies obtained from ascending, descending and sigmoid colon. METHODS: Expression of CYP2C, CYP2E1, CYP3A4, and CYP3A5 mRNA in colon mucosa was determined by RT-PCR. Protein concentration of CYPs was determined using Western blot methods. RESULTS: Extensive interindividual variability was found for the expression of most of the genes. However, expression of CYP2C mRNA levels were significantly higher in the ascending colon than in the sigmoid colon. In contrast, mRNA levels of CYP2E1 and CYP3A5 were significantly lower in the ascending colon in comparison to the descending and sigmoid colon. In sigmoid colon protein levels of CYP2C8 were significantly higher by ~73% than in the descending colon. In contrast, protein concentration of CYP2E1 was significantly lower by ~81% in the sigmoid colon in comparison to the descending colon. CONCLUSION: The current data suggest that the expression of CYP2C, CYP2E1, and CYP3A5 varies in different parts of the colon.

Health risks of chronic moderate and heavy alcohol consumption: how much is too much?

This article presents the proceedings of a symposium held at the meeting of the International Society for Biomedical Research on Alcoholism (ISBRA) in Mannheim, Germany, in October 2004. Most of what we know about the deleterious effects of alcohol in vivo has been gleaned from studies in sober alcoholics recruited from substance abuse treatment programs. Little is known about effects of chronic drinking in the moderate or heavy range encountered in a much larger fraction of modern society. Extrapolation of information on the adverse effects of chronic drinking on organ function from clinical samples to social drinkers in the general population has to be met with great skepticism, as it may lead to wrong conclusions about the chronic effects of alcohol in social drinkers. Several recent studies suggest that moderate alcohol consumption has certain beneficial health effects, whereas heavy social alcohol consumption has recently been associated with organ abnormalities and cognitive deficits. These social drinking effects have attracted great public interest; reports of benefits of moderate drinking have also inspired inappropriate publications by the media, including misleading advertisements by the alcohol producing and distributing industry. Although adverse effects of moderate to heavy drinking on heart, liver, and cancer development have attracted attention by clinicians and researchers for some time, its compromising effects on brain and cognition have only recently been studied. This symposium brought together researchers from different disciplines, who reviewed and presented new data on consequences of social drinking in the areas of clinical neuropsychology and behavior (Drs. Nixon and Meyerhoff), neurophysiology (Dr. Nixon, Ms. De Bruin), neuroimaging (Ms. de Bruin, Dr. Meyerhoff), hepatic disease (Dr. Bode), and cancer (Dr. Seitz). The symposium aimed to clarify both the potential health benefits of moderate alcohol consumption and risks of moderate and heavy drinking on proper organ function and to provide insights and new data to practicing physicians and public health authorities for education on problem drinking.

Acute but not chronic ethanol exposure impairs retinol oxidation in the small and large intestine of the rat.

BACKGROUND AND AIM: Ethanol has been shown to inhibit retinol oxidation at the level of alcohol dehydrogenase in liver and colon but not previously in the small intestine. In the present study we investigated how chronic alcohol feeding and acute ethanol exposure affects retinol dehydrogenase activity in the colon and small intestine of the rat. METHODS: Rats were fed ethanol in a liquid diet for six weeks. Control rats received a similar diet but with ethanol isocalorically replaced by carbohydrates. Retinol dehydrogenase was analyzed from cell cytosol samples from the small and the large intestine with respect to maximum activity (V(max)), Michaelis-Menten constant (K(m)), and inhibition by ethanol (2-43 mM) in vitro. RESULTS: Both the V(max) and the catalytic efficiency (V(max)/K(m)) were found to be significantly higher in the colon than in the small intestine (2.9-3.6 and 54-70 times higher, respectively). While chronic alcohol feeding did not affect these parameters, acute ethanol exposure reduced V(max) and V(max)/K(m) dose-dependently (p < 0.001) in both intestinal segments. CONCLUSION: The present data demonstrate that ethanol markedly inhibits in vitro cytosolic retinol oxidation in the small intestinal mucosa, which is considerably lower than that found in the colon. Considering the vital importance of retinol on intestinal integrity, our finding suggests that this might contribute to the ethanol-induced increase in intestinal permeability.

Water metabolism in rats subjected to chronic alcohol administration.

AIM: While the diuretic action of acute ingestion of alcohol has been studied extensively, the effect of chronic alcohol consumption has received less attention. The aim of the present study was to investigate the effect of chronic alcohol consumption on the balance of water intake and excretion and certain renal functions in rats during a period of 12 months. ANIMALS AND STUDY DESIGN: Male Wistar rats received either alcohol (15% v/v; group A, n = 65) or tap water (group C, n = 35) as drinking fluid. Urine and faeces were collected from 6 rats of each group during 7 days, at monthly intervals. In further experiments, the animals received a low-protein/high-fat diet with and without alcohol. RESULTS: When the rats were fed the standard diet, 24-hour urine excretion was significantly reduced in group A compared with group C. This difference was even more pronounced when the animals were fed the low-protein/high-fat diet. The reduced urine excretion was not due to lower liquid consumption and the pattern of daily excretion of faeces was comparable with that observed for urine excretion. Both sodium and potassium excretion and the diuretic response to an acute water load were significantly reduced in group A compared with group C. The changes in water balance induced by chronic alcohol consumption were reversible within a few days when the rats received water instead of 15% alcohol. CONCLUSIONS: Chronic alcohol consumption has an antidiuretic effect in rats. The percentage of total ingested fluid leaving the body as hidden water loss increases after alcohol consumption by up to 25-26% over control values.