Effect of ethanol and other alcohols on the transport of amino acids and glucose by everted sacs of rat small intestine

A Complex Interplay between Nutrition and Alcohol use Disorder: Implications for Breaking the Vicious Cycle

Approximately 16.5% of the United States population met the diagnostic criteria for substance use disorder (SUD) in 2021, including 29.5 million individuals with alcohol use disorder (AUD). Individuals with AUD are at increased risk for malnutrition, and impairments in nutritional status in chronic alcohol users can be detrimental to physical and emotional well-being. Furthermore, these nutritional deficiencies could contribute to the never-ending cycle of alcoholism and related pathologies, thereby jeopardizing the prospects of recovery and treatment outcomes. Improving nutritional status in AUD patients may not only compensate for general malnutrition but could also reduce adverse symptoms during recovery, thereby promoting abstinence and successful treatment of AUD. In this review, we briefly summarize alterations in the nutritional status of people with addictive disorders, in addition to the underlying neurobiological mechanisms and clinical implications regarding the role of nutritional intervention in recovery from alcohol use disorder.

The Influence of Alcohol Consumption on Intestinal Nutrient Absorption: A Comprehensive Review

Chronic alcohol use has been attributed to the development of malnutrition. This is in part due to the inhibitory effect of ethanol on the absorption of vital nutrients, including glucose, amino acids, lipids, water, vitamins, and minerals within the small intestine. Recent advances in research, along with new cutting-edge technologies, have advanced our understanding of the mechanism of ethanol's effect on intestinal nutrient absorption at the brush border membrane (BBM) of the small intestine. However, further studies are needed to delineate how ethanol consumption could have an impact on altered nutrient absorption under various disease conditions. Current research has elucidated the relationship of alcohol consumption on glucose, glutamine, vitamins B1 (thiamine), B2 (riboflavin), B9 (folate), C (ascorbic acid), selenium, iron, and zinc absorption within the small intestine. We conducted systematic computerized searches in PubMed using the following keywords: (1) "Alcohol effects on nutrient transport"; (2) "Alcohol mediated malabsorption of nutrients"; (3) "Alcohol effects on small intestinal nutrient transport"; and (4) "Alcohol mediated malabsorption of nutrients in small intestine". We included the relevant studies in this review. The main objective of this review is to marshal and analyze previously published research articles and discuss, in-depth, the understanding of ethanol's effect in modulating absorption of vital macro and micronutrients in health and disease conditions. This could ultimately provide great insights in the development of new therapeutic strategies to combat malnutrition associated with alcohol consumption.

Moderate Alcohol Consumption Inhibits Sodium-Dependent Glutamine Co-Transport in Rat Intestinal Epithelial Cells in Vitro and Ex Vivo

Malnutrition is present in chronic alcoholics. However, how moderate alcohol consumption affects the absorption of nutrients like glutamine has not been investigated. Glutamine, an amino acid, is vital to gastrointestinal health. Glutamine is absorbed via sodium-dependent glutamine co-transport (B0AT1; SLC6A19) along the brush border membrane of absorptive villus cells. Rat intestinal epithelial cells (IEC-18) and sixteen-week-old Sprague Dawley rats were administered the equivalent of a 0.04% blood alcohol content of ethanol (8.64 mM; 2 g/kg) to investigate the effect of moderate alcohol on sodium-glutamine co-transport. Sodium-dependent ³H-glutamine uptakes were performed to measure B0AT1 activity. Inorganic phosphate was measured as a function of Na-K-ATPase activity. Protein expression was analyzed by immunohistochemical and Western blot analysis. Ethanol significantly inhibited sodium-dependent glutamine absorption and Na-K-ATPase activity in enterocytes in vitro and ex vivo. Kinetic studies suggested that the mechanism of inhibition was due to decreased maximal rate of uptake (V_max) of the B0AT1 co-transporter, corresponding to decreased B0AT1 protein expression and secondary to an inhibited sodium-gradient at the cellular level in vitro and ex vivo. In all, moderate ethanol significantly inhibited glutamine absorption at the level of decreased B0AT1 expression at the brush border membrane and a reduced sodium gradient, which may contribute to malnutrition present in chronic alcoholics.

Hydrolysis and Transport Characteristics of Tyrosol Acyl Esters in Rat Intestine

Lipophenols such as palmitoyl esters of green-tea polyphenols (GTP) have been allowed for use as food additives for oxidation control. However, their digestive absorption remains unexplored. In this paper, the hydrolysis and transport characteristics of tyrosol acyl esters (TYr-Es) with various fatty acids (C12:0, C14:0, C16:0, C18:0, C18:1, and C18:2) were evaluated using the everted-rat-gut-sac model for the first time. HPLC-UV measurements demonstrated that TYr-Es were hydrolyzed to TYr, which contributed significantly to TYr transport across the sacs. The hydrolysis and transport rates correlated negatively with the chain lengths of their lipid moieties but showed a positive correlation with the degree of unsaturation. In general, all TYr-Es exhibited sustained-release behavior; therefore, the production of TYr-Es may serve as a useful way to prolong the duration of action and further improve the bioactivities of TYr.

Studies on the mechanism of intestinal passage of the food comutagen harman, in the rabbit

The passage of harman (Ha) across rabbit jejunum and its effects on electrical parameters of the intestinal epithelium were studied in vitro using Ussing chambers. A linear relationship between mucosal to serosal flux (Jm-s) and the concentration of Ha (0.25-2 mM) was found. Ha elicited a dose-related decrease in short-circuit current, but did not affect transmural potential difference. At 2 mM, Ha decreased tissue conductance. Despite changes of electrical parameters, Jm-s of Ha was not modified by metabolic effectors such as glucose, colchicine, 2,4-dinitrophenol and ouabain, indicating that passage was dependent neither on membrane movements nor on cell energy. The transport of Ha was not dependent on Na+, but Ha inhibited in a dose-related manner the cotransport of Na+ and glucose. Luminal sodium taurocholate or beta-lactoglobulin had no appreciable effect on transport of Ha, but ethanol elicited a 45% increase in Ha permeability. These results indicate (1) that substantial amounts of Ha can cross the intestinal epithelium by the transcellular pathway and (2) that the passage of Ha, which appears to be diffusional, is not affected by luminal solutes such as glucose, sodium taurocholate and beta-lactoglobulin, but is markedly enhanced by ethanol.

Age related changes in functions and physicochemical properties of rat jejunal brush border membrane after chronic ethanol administration

1. We investigated the chronic effects of a 4 week treatment with ethanol on functions and physicochemical properties of BBM of young and adult rats (2 and 7 months old respectively). 2. In the ethanol treated groups the cholesterol/phospholipid and the protein/lipid ratios as well as the D-glucose uptake and lactase specific activity and Vmax were increased. In spite of a minor alcohol consumption the adult group was the more affected. 3. Membranes from the ethanol fed rats were less fluid and more tolerant to the in vitro addition of ethanol.

The effect of ethanol on intestinal L-leucine absorption in rats

The chronic effect of ethanol on leucine absorption by the whole rat intestine (between duodenum and rectum) was studied using an in vivo multiple-pass perfusion technique. Leucine concentrations in the perfusion medium were 5, 10 and 25 mM respectively in successive passes. Ethanol was administered in drinking water during a one month induction period and then for a four week period of ad libitum ingestion of 30% ethanol solution. The results were compared with ad libitum-fed control rats. The total calorie consumption due to the chow diet plus ethanol increased in the rats which had ingested ethanol when compared with that of the controls. The daily protein intake in ethanol-fed rats was less than that of the controls. No significant differences in morphometric tissue parameters were found between the two experimental groups. Chronic ethanol ingestion provoked a slight (but not significant) decrease in net leucine absorption at 5 mM leucine concentration. In contrast, minor increases in the absorption values were found at 10 and 25 mM leucine concentrations. These findings suggest that the diminished active mechanisms of leucine absorption provoked by ethanol ingestion are compensated for by the enhanced diffusive processes, the passage of the nutrients through the whole intestine, and that the low protein consumption of ethanol-fed rats in ad libitum conditions isn't enough to provoke significant decreases in leucine absorption by the whole intestine.

Effect of chronic ethanol on D-galactose absorption by the rat whole intestinal surface

The in vivo absorption of D-galactose by rat whole intestinal surface after 4 weeks of 30% ethanol ingestion in drinking water has been studied, and the results were compared with ad lib-fed control rats. The total serosal intestinal area was determined by integration obtaining similar values between control and alcohol-treated groups. In the caecum surface of ethanol-fed rats slight but not significant increases were found, while the jejunum area decreased with respect to control rats. Total galactose absorption during 10 min of perfusion was slightly increased in ethanol-fed rats but these results were not significant with the substrate concentrations tested. When absorption data were referred to serosal surface, the absorption/cm2 values in ethanol-fed rats were increased at the studied galactose concentrations although these results were only statistically significant at 10 mM. In conclusion, the present data indicates a slight increase in D-galactose absorptive capacity by the whole intestine in ethanol-fed rats which suggest that the tissue traditionally not evaluated such as caecum and colon could modify the functional response to the absorption nutrients.

Effect of dietary ethanol on gallbladder absorption and cholesterol gallstone formation in the prairie dog

Dietary ethanol has been reported to protect against cholesterol gallstone formation. Because enhanced gallbladder absorption of water is important in cholesterol cholelithiasis, we examined the hypothesis that ethanol acts by inhibiting the absorptive function of the gallbladder. Eighteen adult male prairie dogs were fed a lithogenic liquid diet containing 0.4% cholesterol. Half of the animals received 30% of total calories as ethanol, whereas their pair-fed controls received equicaloric amounts of maltose-dextrin. After 3 months, the gallbladders were inspected for gallstones and crystals, and gallbladder and hepatic bile were analyzed. Cholesterol stones and crystals were present in all nine controls. None of the alcohol-fed animals had stones, but four had cholesterol crystals. Gallbladder cholesterol, phospholipids, and total calcium were significantly decreased in alcohol-fed animals. In both gallbladder and hepatic bile, the cholesterol saturation index was significantly lower in alcohol-fed animals, as was the ratio of trihydroxy to dihydroxy bile salts. The ethanol-supplemented diet produced a significant decrease in the absorption of water by the gallbladder as indicated by changes in the gallbladder bile to hepatic bile ratios of the total bile salt concentration (7.29 +/- 1.25 versus 3.84 +/- 0.56; p less than 0.05) and the total calcium (3.37 +/- 0.24 versus 2.43 +/- 0.29; p less than 0.05). These findings indicate that the protective effect of ethanol may be related to its ability both to inhibit gallbladder absorption of water and to alter the composition of biliary lipids.

Effect of alcohols on gastric and small intestinal apical membrane integrity and fluidity

Duodenal and jejunal brush border membrane vesicle integrity was studied after in vitro treatment of rabbit tissue with ethyl, benzyl or octyl alcohol. The effects of the alcohols on gastric parietal cell apical and microsomal membrane vesicle integrity was also studied. Membrane vesicle integrity was determined from the enclosed volume of the vesicle preparations, measured as [14C]glucose space at equilibrium. Exposure of vesicles to the three alcohols caused concentration dependent decreases in enclosed volume. The rank order of potency of the alcohol was octyl greater than benzyl greater than ethyl. Concentrations greater than or equal to 10 mM benzyl alcohol significantly reduced the enclosed volume of duodenal or jejunal vesicles; jejunal vesicles were disrupted by 625 mM ethanol, whereas 2 M ethanol was required to disrupt the duodenal vesicles. Gastric apical membrane integrity was reduced with 0.25 M ethanol, the vesicles being approximately an order of magnitude more sensitive to ethanol than gross estimates of gastric mucosal damage, but 1 M ethanol was required to significantly damage gastric microsomes. All concentrations of benzyl or octyl alcohol tested (greater than or equal to 5 mM) reduced the enclosed volume of both gastric apical membrane vesicles and gastric microsomes. As determined by shrink-swell techniques, benzyl alcohol permeated duodenal vesicles at a faster rate than NH4Cl (apparent rate constant of 9.89 (0.71) X 10(-3)s-1 compared with 4.48 (0.23) X 10(-3)s-1). Therefore, reductions in enclosed volume in response to alcohol treatment could not be explained by alcohol induced osmotic shrinkage. The enclosed volume of the vesicles after alcohol treatment was negatively correlated with membrane fluidity suggesting a common causal effect, the increased fluidity increasing membrane fragility. Duodenal vesicles were more resistant to disruption by the alcohols compared with gastric and jejunal vesicles.

Ethanol-induced alterations in exocrine pancreatic amino acid transport and secretion

The effects of ethanol on exocrine pancreatic amino acid transport and secretion were investigated during perfusion of the isolated rat pancreas with ethanol concentrations ranging from 0.06% to 4.1%. Amino acid transport was quantitated using a rapid dual isotope dilution technique in which unidirectional substrate uptake (15-20 sec) is assessed relative to an extracellular tracer. Pancreatic secretion evoked by 0.3 microM carbachol was abolished during perfusion with 0.32% ethanol. Influx of L-lysine, L-serine and methylaminoisobutyric acid (MeAIB) was marginally increased by 0.32% ethanol but significantly inhibited during subsequent perfusion with 1.28-4.1% ethanol. Pancreatic oxygen consumption and effluent PCO2 levels decreased with increasing ethanol concentration, and the control venous pH (7.21 +/- 0.01, n = 8) gradually approached arterial pH values (7.46 +/- 0.02, n = 9). These results indicate that low concentrations of ethanol readily inhibit secretagogue-induced pancreatic secretion. Amino acid transport at the basolateral membrane of the exocrine pancreatic epithelium appears only to be inhibited after acute exposure to high ethanol concentrations.

Interaction between glucose diet and ethanol on rat liver microsomal induction and liver plasma membrane damage in chronic hexachlorobenzene intoxication

Male Wistar rats fed for 60 days a glucose diet containing 17.5 mmol hexachlorobenzene/kg show a less pronounced increase in serum parameters and microsomal cytochrome P-450 concentration and a lower decrease in liver plasma membrane 5'-nucleotidase, K+, Na+- and Mg++-adenosine triphosphatase activities than the controls fed standard diet + hexachlorobenzene. Addition of 10% ethanol to the drinking water eliminates the "glucose effect". The glucose diet and ethanol exert contrasting effects on microsomal enzyme induction and liver plasma membrane damage in hexachlorobenzene intoxication.

Effect of chronic ethanol intake on lactase activity and active galactose absorption in rat small intestine

The effects of feeding a nutritionally adequate liquid diet containing 5% ethanol to rats over a four week period on intestinal lactase activity and the kinetics of jejunal galactose absorption in vivo have been determined. Both lactase activity and the maximum capacity for active, saturable galactose absorption (Jmax) were increased significantly after chronic ethanol ingestion. In contrast, uptake of the sugar via the phlorhizin-insensitive (passive) route was unaffected by ethanol. Our results imply the presence of an increased maturity of the enterocyte population on the villus surface in response to ethanol. The relevance of this work to uptake studies in alcoholics is briefly discussed.

Effect of ethanol on organic ion transport in rabbit kidney

The effect of ethanol on the transport of organic ions in rabbit kidney cortical slices was studied. Ethanol at a concentration of 4 to 10% (v/v) reversibly inhibited the slice uptake of the organic anion, p-aminohippurate (PAH), in a dose-dependent manner, but had no significant effect on that of the organic cation, tetraethylammonium (TEA). Overall, the inhibitory effect on PAH uptake increased with the length of the hydrocarbon chain, with an I50 of 7.7, 0.9, and 0.05% for ethanol, butanol, and heptanol, respectively. The efflux of PAH was significantly decreased in the presence of 8% ethanol. Kinetic analysis indicated that ethanol decreased Vmax without a significant change in Km. Lowering the Na concentration in the incubation medium from 130 to 20 mM resulted in a disappearance of the above described inhibitory effect of ethanol on PAH uptake. Although Na-K-ATPase activity of renal cortical microsomes was significantly inhibited by ethanol (6-10%), butanol (1%), and heptanol (0.1%), there was no clear correlation between the effects of alcohols on PAH transport and/or Na-K-ATPase. Nevertheless, the results suggest that ethanol inhibits reversibly the Na-dependent transport of PAH from the medium into the cell across the basolateral membrane through a mechanism yet to be elucidated. The high degree of correlation between I50 and the partition coefficients of the alcohols suggested that their interaction with membrane lipids is important for the inhibition of PAH uptake, and also that PAH (but not TEA) transport is affected by alteration of the lipid environment of the membrane.

Ethanol inhibits Na+-gradient-dependent uptake of L-amino acids into intestinal brush border membrane vesicles

Brush border membrane vesicles from hamster jejunum were used to investigate the effects of ethanol on Na+-dependent transport of amino acids. Imposition of an inwardly directed gradient of NaCl resulted in transient accumulation of L-alanine and L-phenylalanine, followed by a gradual decline to equilibrium levels. Ethanol reduced both the rate of uptake and the maximum accumulation of these amino acids without altering the final equilibrium level. The inhibitory effects of ethanol on L-alanine uptake were dose dependent and reversible. On the other hand, ethanol had no effect on the rate of uptake of L-alanine or the final equilibrium level attained when vesicles were incubated with a KCl gradient or when NaCl was equilibrated across the vesicle membrane. These results suggest that ethanol does not inhibit Na+-dependent uptake of neutral amino acids by direct inhibition of the Na+-dependent transport systems for these solutes.

Ethanol selectively affects Na+-gradient dependent intestinal transport systems

Moderate concentrations of ethanol reduce the velocity of uptake of three representative Na+-symport systems (D-glucose, L-alanine, L-ascorbate), whether electrogenic (the first two) or electroneutral (L-ascorbate). This 'inhibition' is observed only if these transport systems are tested in the presence of an initial Na+ gradient (out greater than in); no inhibition is found in tracer-equilibrium exchange measurements. A representative Na+-independent system (D-fructose) is not inhibited by ethanol. 'Passive diffusion' (measured as uptake of L-glucose) is increased somewhat by alcohol. All these observations can be rationalized [as suggested by Tillotson et al. (1981) Arch. Biochem. Biophys. 207, 360-370] by an effect of ethanol on passive diffusion, which leads to a faster collapse of the Na+ gradient, with the resulting reduction of the uptake velocities of Na+-dependent transport systems when tested with the added driving force of an Na+ out----in gradient.

Functional properties of isolated hepatocytes from ethanol-treated rat liver

Gluconeogenesis and palmitate incorporation into triacylglycerols and phosphatidylcholine were measured in isolated hepatocytes from control and ethanol-treated rats. Basal gluconeogenesis and its hormonal response decreased in hepatocytes from ethanol-treated animals; palmitate incorporation into triacylglycerols increased. In ethanol-treated rat liver, 45Ca2+ uptake and methylating capacity were reduced, and the hormonal response exhibited differences in binding parameters of insulin.

Effect of ethanol on intestinal uptake of fatty acids, fatty alcohols, and cholesterol

The effect of acute exposure of the rabbit jejunum to ethanol on the uptake of fatty acids, fatty alcohols, and cholesterol was examined using a previously validated in vitro technique. The effective resistance of the intestinal unstirred water layer was determined from the rate of uptake of a homologous series of fatty alcohols. The addition of ethanol to the incubation or preincubation solutions had no effect on the uptake of these probes when the bulk phase was stirred at 600 rpm, but uptake was higher in the ethanol-exposed samples when the bulk phase was unstirred. Increasing the concentration of ethanol in the bulk phase was associated with a progressive decline in the rate of uptake of acetic, lauric, myristic, and palmitic acids, whereas the uptake of hexanoic, octanoic, and decanoic acids was unaffected, and the uptake of cholesterol was increased. Acute exposure of the intestine to ethanol was associated with an increase in the electrical conductance of the tissue, with no associated change noted in the tight junctions on transmission electron microscopy or in the surface epithelium on scanning electron microscopy. The results suggest that acute exposure of the rabbit intestine to ethanol is associated with a selective decline in the passive permeability properties of the membrane towards only certain lipids and that the effective resistance of the unstirred layer is influenced by ethanol only when the bulk phase is unstirred and the resistance is high.

Acute exposure of rabbit jejunum to ethanol. In vitro uptake of hexoses

The effect of acute exposure of rabbit jejunum to ethanol on the uptake of three hexoses was examined in vitro. With ethanol present in the preincubation medium for 30 min, or directly in the incubation medium for 6 min, glucose uptake was reduced. Kinetic analysis demonstrated that ethanol in the preincubation medium was associated with a rise in the value of the apparent Michaelis constant (Km*), whereas the inhibition of glucose uptake observed with ethanol present directly in the incubation medium was associated with a reduction in the apparent passive permeability coefficient (Pd*), a reduction in the maximal transport rate (Jdm), and an increase in Km*. When increasing concentrations of ethanol were added to the preincubation or to the incubation medium, there was a reduction in the uptake of both 1 mM and 40 mM glucose, galactose, and 3-O-methyl glucose. The addition of 40 mM galactose or 1 mM phloridzin to 40 mM glucose was associated with a 50% reduction in glucose uptake, but this uptake was not further inhibited by the addition of 6% ethanol (v/v). Similarly, the uptake of 3-O-methyl glucose was inhibited by the addition of 40 mM glucose or galactose but no further reduction in uptake was achieved by adding ethanol. Finally, galactose uptake was inhibited by adding 40 mM glucose or 40 mM 3-O-MG, but the addition of 6% ethanol was associated with no further decline in the uptake of galactose.(ABSTRACT TRUNCATED AT 250 WORDS)

Metabolic fate of ammonia in the rat after ethanol loading

Repeated ethanol loading i.p. produced significant changes in ammonia concentration of different tissues in the rat despite increased levels of urea and glutamine in muscle, kidney and heart.

Protein-calorie malnutrition associated with alcoholic hepatitis. Veterans Administration Cooperative Study Group on Alcoholic Hepatitis

Three hundred sixty-three alcoholic patients with alcoholic hepatitis were studied in six Veterans Administration medical centers. By history, alcohol consumption was 227.9 g per day, with a mean duration of 23.8 years. Cirrhosis accompanied the alcoholic hepatitis in 58.7 percent of the patients who underwent biopsy or autopsy. Complete nutritional assessment was performed in 284 patients, and observed nutritional changes were classified into those associated with marasmus or those characterizing kwashiorkor. A smaller comparison group of 21 alcoholic patients matched for age and alcohol consumption but without clinically evident liver disease was also studied in an identical manner. None of the patients with liver disease was completely free from malnutrition, whereas 62 percent of the alcoholic patients without liver disease showed abnormalities. In patients with alcoholic hepatitis, some findings associated with marasmus were seen in 86 percent, and some features of kwashiorkor were observed in 100 percent. When present together, the complete picture of kwashiorkor and marasmus correlated closely with the clinical severity of the liver disease (p less than 0.005). The nearly constant association of either complete or partial kwashiorkor or marasmus suggests that the separation of these two entities is artificial in alcoholic patients with liver disease. Although, experimentally, malnutrition may not be essential for the development of alcoholic hepatitis, clinically, it appears to precede the development of the liver injury, which suggests an interaction. Recognition is important so that appropriate nutritional therapy can be provided.

Alcohol and the gastrointestinal tract

The effects of acute and chronic ethanol ingestion on esophageal motility and the potential complications of these alterations are reviewed. Injury to the gastric mucosa and the small intestine and alterations in intestinal absorption can also result from alcohol abuse.

Effect of ethanol on morphology and total, capillary, and shunted blood flow of different anatomical layers of dog jejunum

On the basis of previous studies in our laboratory we postulated that the ethanol-induced alteration in jejunal morphology was the result of its effect on the microcirculation. The present study was undertaken to examine the validity of this hypothesis. Accordingly, the effects of intraluminal ethanol perfusion (3.0 and 6.0% w/v) on mucosal morphology; water, glucose, and sodium transport; and regional blood flow were examined in in vivo jejunal segments of pentobarbital-anesthetized dogs. Compared to control segments, those perfused with ethanol exhibited a significant increase in the prevalence of morphological alterations of the mucosa, consisting of subepithelial fluid accumulation (bleb formation) and exfoliation. Those villi with epithelial damage exhibited villus cores significantly shorter than those with a normal, undamaged epithelium. Segments perfused with ethanol exhibited a depressed net water absorption, to the point that net secretion occurred in the segments perfused with 6% ethanol. Net absorption of glucose was similarly depressed by intraluminal perfusion with ethanol, whereas net absorption of sodium was unaffected. Regional jejunal blood flows were estimated using a dual, radiolabeled microsphere technique. Both total jejunal wall and total mucosal blood flow (in ml/min/100 g dry tissue) in the ethanol-perfused segments were significantly increased over control. Similarly, jejunal wall and mucosal capillary blood flows were increased by ethanol perfusion. Neither submucosal nor muscularis blood flows were affected by intraluminal perfusion with ethanol. Compared to control, shunting or nonentrapment of 9-micron microspheres was increased in the mucosa of the ethanol-perfused segments. In contrast to this, shunting of 9-micron microspheres in the submucosa and muscularis was unaffected by intraluminal perfusion with ethanol. It therefore appears that the ethanol-induced mucosal morphological alterations are accompanied by a localized mucosal hyperemia, and an increased shunting of blood through the mucosa. Based on the results of this and other studies, a microvascular mechanism was tentatively proposed to explain the pathogenesis of the ethanol-induced morphological changes.

Nutrition and immunity after peritoneovenous drainage of intractable ascites in cirrhotic patients

Severe malnutrition and related impaired cell-mediated immunity are commonly found in cirrhotic patients with intractable ascites and may be responsible for the poor prognosis of these patients. The effects of LeVeen peritoneovenous shunting of ascites on protein reserves and cell-mediated immunity were studied in 31 cirrhotic patients with intractable ascites over a period of 1 year following operation. Arm-muscle circumference, serum albumin, and transferrin levels markedly increased and became close to the normal values. In the same period, delayed hypersensitivity improved. Although the lymphocyte count and the absolute T cell concentration in peripheral blood remained low after peritoneovenous shunting, the in vitro lymphoblastic transformation in response to phytohemagglutinin was augmented. An increased capacity to eat normal meals and the resumption of a good appetite due to the discontinuation of a salt-restricted diet seemed to be the most important factors in the dramatic improvement in the nutritional status of these patients. Restriction from heavy alcohol use may have also contributed, although the patients had already stopped drinking for several months before operation. Improvement in cell-mediated immunity might have been secondary to the increase in protein reserves.

Plasma amino-acid patterns in liver disease

Plasma amino-acid concentrations were measured in 167 patients with liver disease of varying aetiology and severity, all free of encephalopathy, and the results compared with those in 57 control subjects matched for age and sex. In the four groups of patients with chronic liver disease (26 patients with chronic active hepatitis, 23 with primary biliary cirrhosis, 11 with cryptogenic cirrhosis, and 48 with alcoholic hepatitis +/- cirrhosis) plasma concentrations of methionine were significantly increased, while concentrations of the three branched chain amino-acids were significantly reduced. In the first three groups of patients plasma concentrations of aspartate, serine, and one or both of the aromatic amino-acids tyrosine and phenylalanine were also significantly increased, while in the patients with alcoholic hepatitis +/- cirrhosis plasma concentrations of glycine, alanine, and phenylalanine were significantly reduced. In the three groups of patients with minimal, potentially reversible liver disease (31 patients with alcoholic fatty liver, 10 with viral hepatitis, and 18 with biliary disease) plasma concentrations of proline and the three branched chain amino-acids were significantly reduced. Patients with alcoholic fatty liver also showed significantly reduced plasma phenylalanine values. Most changes in plasma amino-acid concentrations in patients with chronic liver disease may be explained on the basis of impaired hepatic function, portal-systemic shunting of blood, and hyperinsulinaemia and hyperglucagonaemia. The changes in patients with minimal liver disease are less easily explained.

Low-molecular-weight polyethylene glycol as a probe of gastrointestinal permeability after alcohol ingestion

Gastrointestinal permeability has been assessed previously by the excretion of PEG-400, which consists of inert molecules that are neither degraded nor metabolized and are excreted intact in the urine. We report here the effects of alcohol on gastrointestinal permeability using PEG-400. Ten grams of PEG-400 dissolved in 60 ml of water were given to 12 intoxicated alcoholics (mean blood alcohol: 2406 mg/liter). The mean urinary excretion of PEG-400 in the following 6 hr was 3.75 +/- 0.3 g SEM. When repeated after sobering up (mean elapsed time: 45 hr), all except one subject showed a decrease in PEG-400 excretion (mean: 2.08 +/- 0.2 g) (P less than 0.001). Similar experiments were conducted in two series with 12 normal controls. (1) In 7 subjects the administration on consecutive days of (a) PEG-400 (10 g) alone, (b) 10.2 g (0.42 mol) of ethanol plus PEG-400 (10 g), (c) PEG-400 (10 g) alone, and (d) PEG-400 (10 g) plus a diuretic (40 mg furosemide) resulted in the following values of PEG-400 excretion in urine: (a) 2.12 +/- 0.3 g; (b) 3.5 +/- 0.3 g, P less than 0.005; (c) 2.02 +/- 0.4, NS; and (d) 2.2 +/- 0.2 g, NS. (2) In the second experiment (5 subjects) the administration on subsequent days of (a) PEG-400 (10 g) + 0.42 mol of urea; (b) PEG-400 (10 g) + 19.2 g ethanol; (c) PEG-400 (10 g) + 0.42 mol of urea resulted also, as in the previous experiment, in increased urinary excretion of PEG-400 after the solution (b) containing ethanol (P less than 0.001). Peak serum levels of PEG-400 were (a) 0.094 +/- 0.01 g/liter; (b) 0.152 +/- 0.02 g/liter (P less than 0.05); and (c) 0.095 +/- 0.01 (P less than 0.05). The ratio of urea--creatinine clearance and urinary volumes were the same in the three periods. Therefore, PEG-400 excretion was not related to changes in urinary clearance or in volume, since the furosemide increased the volume but not PEG-400 excretion. It is concluded that ethanol increases the permeability of the gastrointestinal tract as measured by the PEG-400 test, both in chronic alcoholics during intoxication and in nonalcoholics after a small dose of ethanol. The permeability alteration is transient once ethanol ingestion stops.

Intestinal folic acid absorption and the acid microclimate. The effects of compounds relevant to folate malabsorption

The effect s of various substances and circumstances on folic acid absorption and surface pH were investigated in vitro in rat proximal jejunum. Prior consumption of alcohol and libitum, phenytoin and in vitro methotrexate had no effect on folate absorption. In contrast, ethanol in vitro, low sodium ion containing buffers in vitro and oral methotrexate given prior to experiment reduced absorption. Folate absorption did not correlate with water movement since methotrexate decreased folate but enhanced fluid absorption, ruling out direct coupling. Surface pH was elevated by the low sodium ion containing buffers, ethanol in vitro and oral methotrexate, correlating inversely with folate absorption. The parallelisms between absorption and changes in surface pH support the microclimate hypothesis of folic acid absorption where the rate of transport is largely determined by the surface pH of the proximal jejunum.

Ethanol-induced changes in properties of rat brian ribosomes

Altered in vivo and in vitro brain protein metabolism have been demonstrated in rodents following long-term ethanol ingestion. In the present study, ethanol effects were examined on properties of brain ribosomes of male Sprague-Dawley rats ingesting a specially formulated Lieber-DeCarli liquid diet. The development of physical dependence was demonstrated by the presence of withdrawal reactions within 24 hr of ethanol abstinence. Data showed significant inhibition of in vitro protein synthesis by ribosomes from the "ethanol" and "1-day-withdrawn" groups. Partial reversal of inhibition occurred by using a control brain pH 5 enzymes source instead of the matched source. The observed [14C]leucine-incorporating activity was temperature dependent, with the optimum temperature being 37 degrees C. The determination of the state of ribosomal aggregation showed an increased monosomes--disomes ratio in the "ethanol" group. The ratio was even more increased in the "1-day-withdrawn" group. Data suggest that reduced ribosomal binding to stable mRNA may be a contributing factor in the ethanol-induced effects on protein synthesis.

Drugs, alcohol and malabsorption

Alcohol and a number of drugs (e.g., neomycin, cholestyramine, antacids, laxatives, paraminosalicyclic acid, colchicine and oral hypoglycemic agents) can cause malabsorption due to drugs and alcohol is surveyed. Examined in detail are the mechanisms of malabsorption produced by neomycin and cholestyramine, and the factors responsible for malabsorption in the chronic alcoholic.

Inhibitory effect of ethanol on growth and solute accumulation by Saccharomyces cerevisiae as affected by plasma-membrane lipid composition

Incorporation of ethanol (1.0 or 1.25 M) into exponential-phase cultures of Saccharomyces cerevisiae NCYC 366 growing anaerobically in a medium supplemented with ergosterol and an unsaturated fatty acid caused a retardation in growth rat, which was greater when the medium contained oleic rather than linoleic acid. Ethanol incorporation led to an immediate drop in growth rate, and ethanol-containing cultures grew at the slower rate for at least 10 h. Incorporation of ethanol (0.5 M) into buffered (pH 4.5) cell suspensions containing D-[6-3H] glucose, D-[1-14C] glucosamine, L-[U-14C] lysine or arginine, or KH232PO4 lowered the rate of solute accumulation by cells. Rates of accumulation of glucose, lysine and arginine were retarded to a greater extent when cells had been grown in the presence of oleic rather than linoleic acid. This difference was not observed with accumulation of phosphate. Ethanol was extracted from exponential-phase cells by four different methods. Cells grown in the presence of linoleic acid contained a slightly, but consistently, lower concentration of ethanol than cells grown in oleic acid-containing medium. The ethanol concentration in cells was 5-7 times greater than that in the cell-free medium.

Effects of ethanol on the determinants of intestinal transport

The interplay between the stomach, liver, pancreas, and the small intestine and their influence on the effects of ethanol on the determinants of intestinal transport are examined.

Effect of ethanol on glucose and water absorption in hamster jejunum in vivo. Methodological problems: anesthesia, nonabsorbable markers, and osmotic effect

We studied the effect of ethanol on glucose and water absorption in vivo. In preliminary experiments, using sodium amytal anesthesia, we found that control animals, whose jejunal segment was perfused without ethanol, required more anesthetic agent than those perfused with ethanol. Thus, to allow for unbiased comparison of the absorption data between the two groups of animals, all absorption studies were carried out on conscious restrained hamsters. We found that ethanol did not influence the permeability of the jejunum to polyethylene glycol (PEG) and meglumine diatrizoate. In addition, ethanol did not influence the time required for the onset of steady-state absorption. Using both the gravimetric and the electrical methods, we were unable to show any measurable osmotic pressure exerted by ethanol (150-1050 mM) on the hamster jejunum. In the absorption studies we found that perfusion of the hamster jejunum with five increasing concentration of ethanol (450-1050 mM) appeared to cause a concentration-dependent depression in steady-state glucose transport. Water transport was depressed only when 4.8% (1050 mM) ethanol was perfused.

Effects of ethanol on sodium, 3-O-methyl glucose, and L-alanine transport in the jejunum

Effects of ethanol on Na+, Cl-, 3-O-methyl glucose (3-O-MG), and L-alanine fluxes were studied in the isolated rattit jejunal mucosa. Ethanol (3% v/v present on both sides of the mucosa) decreased electrical potential difference (PD), short-circuit current (Isc) and inhibited active transport of Na+, 3-O-MG, and L-alanine. This concentration also increased the permeability of the mucosa for Cl-, 3-O-MG, and L-alanine. Ethanol at 5.4% potentiated the effects on PD, Isc, and the permeability for electrolytes and organic substances. These effects of ethanol could not be fully explained by an osmotic action.

Effect of folate deficiency and ethanol ingestion on intestinal folate absorption

The effects of folate deficiency, generalized malnutrition, and alcohol ingestion on jejunal transport, mucosal uptake, and reduction of folic acid were evaluated in rats. As measured by an everted gut sac technique, a folate-deficient diet fed ad libitum did not alter transport or mucosal uptake of folate. Partial starvation, which was produced in rats pair-fed with animals ingesting ethanol, increased jejunal folate transport and mucosal uptake in animals ingesting either a folate-deficient or control diet. A 20% ethanol ingestion by rats consuming folate-deficient or control diets resulted in transport and mucosal uptake rates intermediate in value compared to those from ad libitum fed and pair-fed groups. No differences in reduction of folic acid were found. These results suggest that folate depletion and ethanol ingestion, alone or in combination, do not affect the ability of the rat jejunal to transport folate but that partial starvation results in an increase in folate transport activity.

On the mechanism of the inhibitory effect of ethanol on intestinal glucose and water absorption

Experiments were performed to investigate whether the inhibitory effect of ethanol on intestinal glucose transport is related to its action on the brush border or on the ATPase-dependent sodium pump of the basolateral membrane of the enterocyte. We compared the effect of ethanol on glucose and water transport when it was added either to the mucosal or to the serosal solution of an in vitro preparation of hamster jejunum. The purpose of the addition of ethanol to the serosal solution was to mimic a situation similar to that produced when ouabain is placed on the serosal side to inhibit the ATPase-dependent sodium pump at the basolateral membrane. The presence of 450 mM ethanol (2.07%) in the mucosal solution depressed glucose and water transport by 40 and 63%, respectively, but the presence of the same concentration of ethanol on the serosal side had no effect on glucose and water absorption. These findings seem to indicate that the depressing effect of ethanol on intestinal glucose and water transport cannot be ascribed to the inhibition of the Na+, K+-sensitive ATPase-dependent sodium pump located at the basolateral membrane.

Effect of acute ethanol ingestion on fat absorption

A test meal (300 mg casein, 600 mg sucrose, 100 mg corn oil, tracer dose of 9.10(3)H oleic acid) was given to fasting adult rats with intestinal lymph fistulas. One group received an acute oral dose of ethanol (3.2 g/kg body weight) simultaneously with the test meal. Controls received 2.5 ml of water instead of ethanol. Ingestion of ethanol temporarily delayed the removal of lipid radioactivity from the stomachs. More than 25% of radioactivity fed remained 8 hr after feeding whereas with control rats less than 10% of lipid radioactivity fed remained 6 hr after feeding. In controls and ethanol-treated rats, the amounts of exogenous lipids in the intestinal lumen and mucosa were low and similar enough. Quantities of endogenous and exogenous lipids found in the lymph collected during 24 hr after feeding were similar in the two groups, but the fat absorption peak was found after 6 hr in alcoholic rats and before 6 hr in controls. This delay was probably due to the retention of lipids in the stomach. More of the exogenous lipid was always transported by small particles moving in the region of alpha1 globulins in cellulose acetate electrophoresis than by larger particles remaining at the origin. This proportion was enhanced in the ethanol-treated animals. The larger fat particles were richer in endogenous fatty acids in alcohol-treated rats than in controls.

Effect of ethyl acetate on the transport of sodium and glucose in the hamster small intestine in vitro

The effect of ethyl acetate on Na+, water and glucose transport, as well as on glucose and electrolyte intracellular concentrations in everted and cannulated sacs of hamster jejunum, have been studied. Ethyl acetate, a substance that easily penetrates and delivers energy to the cell, strongly stimulates net glucose and Na+ transport. The explanation of the experimental results takes into account the possibility of the existence of an active extrusion of glucose at the level of the basolateral membrane of the enterocyte.