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PubMed1990

The generation of cytotoxic T lymphocytes against acetaldehyde-modified syngeneic cells.

The major metabolic product of ethanol is acetaldehyde. It is highly reactive with proteins. In situ this modification is significant enough to generate an antibody response. Whether an effector cellular immune response can be generated against these acetaldehyde modified adducts on syngeneic cells is not known. In this paper we have demonstrated in the murine system that acetaldehyde modified splenic cells can generate cytotoxic T lymphocytes (CTL). These CTL are specific for the acetaldehyde modified syngeneic cells, and not acetaldehyde modified allogeneic cells. The ability of the CTL to lyse-specific targets is dependent on the formation of stable acetaldehyde adducts. Cold target inhibition studies reveal that modified syngeneic cells can inhibit lysis as effectively as unmodified cells. Therefore, the present study lends support to the hypothesis that acetaldehyde modified cells can generate a cellular immune response and may do so in pathologic states.

Acetaldehyde↗
PubMed1993

Determinants of ethanol and acetaldehyde metabolism in chronic alcoholics.

We have studied the factors determining the rate of ethanol and acetaldehyde metabolism in a group of 25 alcoholics with varying degrees of liver lesion (from normal liver to cirrhosis) and in six nonalcoholic cirrhotics. In alcoholics the ethanol metabolic rate was related to hepatic function, estimated either by the aminopyrine breath test (r = 0.70, p < 0.001) or the indocyanine green clearance (r = 0.76, p < 0.01), and was independent of the activity of hepatic alcohol dehydrogenase and hepatic blood flow. In nonalcoholic cirrhotics blood acetaldehyde was always below the detection limit (0.5 microM), but elevated levels were found in 14 out of the 25 alcoholics. Alcoholics with elevated blood acetaldehyde showed a significantly higher ethanol metabolic rate than alcoholics with undetectable acetaldehyde (120 +/- 17 mg/kg/hr vs 104 +/- 11 mg/kg/hr, p < 0.02), but no differences were observed in the activities of alcohol and aldehyde dehydrogenases. Peak blood acetaldehyde levels were directly related to the ethanol metabolic rate (r = 0.48, p < 0.02), but not to activities of hepatic alcohol or aldehyde dehydrogenases. These results indicate that in chronic alcoholics the main determinant of the ethanol metabolic rate is hepatic function, while the rise of blood acetaldehyde is mainly dependent on the ethanol metabolic rate. Alcohol and aldehyde dehydrogenase activities do not seem to be rate-limiting factors in the oxidation of ethanol or acetaldehyde.

Acetaldehyde↗
PubMed1993

Reaction of acetaldehyde with proteins: formation of stable fluorescent adducts.

The properties of stable acetaldehyde-protein adducts, using bovine serum albumin as a model protein, were investigated. Upon prolonged incubation at 37 degrees C and pH 7.4, the reaction of acetaldehyde and albumin yielded stable adducts that exhibited fluorescent properties. Reaction mixtures of acetaldehyde with polylysine or ethylamine also formed fluorescent products with similar fluorescent spectral properties like acetaldehyde-albumin adducts, indicating that the amino groups of protein alone can generate fluorescent products on reaction with acetaldehyde. When reactions of acetaldehyde with albumin or polylysine were conducted at 22 degrees C, stable binding reached a maximum after 24 hr of incubation and essentially remained at this level during the remaining 216 hr of incubation, and minimal-to-no fluorescence was associated with this binding. At 37 degrees C, stable binding was greater and increased continuously over the entire 216 hr of incubation. After an initial lag period of 24 to 48 hr, increases in fluorescence intensity paralleled the increases in stable binding. The presence of sodium cyanoborohydride, which reduces Schiff bases, in the reaction mixtures prevented fluorescence, indicating that Schiff bases are intermediates in the formation of fluorescent products. Both stable binding and fluorescence intensities were minimally affected by exhaustive dialysis (up to 144 hr), indicating that the fluorescent products were quite stable. These results suggest that an initial reaction of a Schiff base with another acetaldehyde molecule via an aldol condensation reaction gives rise to the formation of a crotonaldehyde Schiff base derivative. This reactive intermediate could then undergo further condensation reactions and form advanced conjugated products, some of which could be fluorescent.

Acetaldehyde↗
PubMed1995

In vitro comparison of the effects of ethanol and acetaldehyde on dorsal root ganglion neurons.

Results of previous experiments designed to investigate the role of acetaldehyde, the primary metabolite of ethanol, have been contradictory. Experiments have provided evidence that supports and refutes the idea that acetaldehyde is responsible for the teratogenic effects observed in fetal alcohol syndrome. In the present study, cell culture techniques were used to examine the effects of acetaldehyde, both independently and in conjunction with ethanol. The purpose was to determine whether acetaldehyde had any effect on survival and process outgrowth of dorsal root ganglion (DRG) neurons cultured in vitro. This study revealed that acetaldehyde was as toxic to DRG survival as is ethanol, but had a lesser effect on neurite outgrowth than ethanol. Also, acetaldehyde and ethanol do not act synergistically to damage neurons in culture. The results indicate that, although acetaldehyde is probably not solely responsible for ethanol neurotoxicity, it does exhibit a secondary toxicity that could be the subject of future studies.

Acetaldehyde↗
PubMed1996

In vitro alcohol dehydrogenase-mediated acetaldehyde production by aerobic bacteria representing the normal colonic flora in man.

Excessive ethanol consumption has been related with the development of liver cirrhosis, as well as with rapid intestinal transit time and diarrhea. Moreover, heavy drinking is associated with an increased incidence of cancer of the oropharynx, larynx, esophagus, and colorectum. Acetaldehyde of microbial origin has recently been suggested as a possible pathogenic factor behind this alcohol-associated gastrointestinal morbidity. The present in vitro study was aimed to investigate alcohol dehydrogenase activity and acetaldehyde formation capacity of some major aerobic bacteria representing the normal colonic flora in man. Cytosolic alcohol dehydrogenase activity and cytosolic protein concentration were determined spectrophotometrically. Alcohol dehydrogenase activity was then calculated as nmoles of reduced substrate produced by milligrams of protein per minute. The ability of different bacteria to produce acetaldehyde was determined by incubating the intact bacterial suspension in closed vials containing ethanol (final concentration 22 mM) for 1 hr at 37 degrees C. The acetaldehyde formed during the incubation was analyzed by headspace gas chromatography. Marked differences in the alcohol dehydrogenase activity and acetaldehyde forming capacity were found among the strains tested. The alcohol dehydrogenase activity varied from 606 +/- 91 nmol/min/mg protein (Escherichia coli IH 50546) to 1 +/- 0.2 nmol/min/mg protein (E. coli IH 50817), and acetaldehyde formation varied from 1,717 +/- 2 nmol acetaldehyde/10(9) colony-forming units (Klebsiella oxytoca IH 35403) to 5 +/- 2 nmol acetaldehyde/10(9) colony-forming units (Pseudomonas aeruginosa ATCC 27853). There was a statistically significant correlation (r = 0.77; p < 0.001) between alcohol dehydrogenase activity and acetaldehyde production from ethanol, strongly suggesting the catalytic role of bacterial alcohol dehydrogenase in this reaction.

Acetaldehyde↗
PubMed1994

Potentiating effect of inhaled acetaldehyde on bronchial responsiveness to methacholine in asthmatic subjects.

BACKGROUND: It has recently been reported that acetaldehyde induces bronchoconstriction indirectly via histamine release. However, no study has been performed to assess whether acetaldehyde worsens bronchial responsiveness in asthmatic subjects so this hypothesis was tested. METHODS: Methacholine provocation was performed on three occasions: (1) after pretreatment with oral placebo and inhaled saline (P-S day), (2) after placebo and inhaled acetaldehyde (P-A day), and (3) after a potent histamine H1 receptor antagonist terfenadine and acetaldehyde (T-A day) in a double blind, randomised, crossover fashion. Nine asthmatic subjects inhaled 0.8 mg/ml acetaldehyde or saline for four minutes. After each inhalation a methacholine provocation test was performed. RESULTS: Methacholine concentrations producing a 20% fall in FEV1 (PC20-MCh) on the P-A day (0.48 mg/ml, 95% CI 0.21 to 1.08) and T-A day (0.41 mg/ml, 95% CI 0.22 to 0.77) were lower than those on the P-S day (0.85 mg/ml, 95% CI 0.47 to 1.54). There was no change in the PC20-MCh between the P-A and T-A days. A correlation was observed between the logarithmic values of PC20-MCh (log PC20-MCh) on the P-S day and the potentiating effect of acetaldehyde on the methacholine responsiveness [(log PC20-MCh on P-A day)-(log PC20-MCh on P-S day)] (rho = 0.82). CONCLUSIONS: Acetaldehyde induces bronchial hyperresponsiveness in patients with asthma by mechanisms other than histamine release.

Acetaldehyde↗
PubMed1983

Artifactual production and recovery of acetaldehyde from ethanol in urine.

Ethanol (1575 mg/L) incubated with fresh urine from healthy, ethanol-free subjects yields acetaldehyde. The concentration of acetaldehyde depends upon temperature, time of incubation, and pH. In samples made hypertonic with sodium chloride (200 mg/mL) and in samples filtered through 0.45-micron membranes, acetaldehyde production was not decreased. L-Ascorbic acid (0.1 mg/mL) added to normal pooled urine caused a threefold increase in acetaldehyde production but thiourea (7.6 mg/mL) stopped it. This suggests that the oxidation of ethanol to acetaldehyde is catalyzed by the semidehydroascorbate peroxy radical of ascorbic acid. Recovery of acetaldehyde added to urine was less than 100% over the pH range 1.5 to 10. Relative to blood, artifactual production of acetaldehyde from ethanol in urine is more easily controlled and is up to an order of magnitude less but corrections for the variables above are still required.

Acetaldehyde↗
PubMed2005

Acetaldehyde disrupts tight junctions and adherens junctions in human colonic mucosa: protection by EGF and L-glutamine.

Acetaldehyde, a toxic metabolite of ethanol oxidation, is suggested to play a role in the increased risk for gastrointestinal cancers in alcoholics. In the present study, the effect of acetaldehyde on tyrosine phosphorylation, immunofluorescence localization, and detergent-insoluble fractions of the tight junction and the adherens junction proteins was determined in the human colonic mucosa. The role of EGF and L-glutamine in prevention of acetaldehyde-induced effects was also evaluated. Acetaldehyde reduced the protein tyrosine phosphatase activity, thereby increasing the tyrosine phosphorylation of occludin, E-cadherin, and beta-catenin. The levels of occludin, zonula occludens-1, E-cadherin, and beta-catenin in detergent-insoluble fractions were reduced by acetaldehyde, while it increased their levels in detergent-soluble fractions. Pretreatment with EGF or L-glutamine prevented acetaldehyde-induced protein tyrosine phosphorylation, redistribution from intercellular junctions, and reduction in the levels of detergent-insoluble fractions of occludin, zonula occludens-1, E-cadherin, and beta-catenin. These results demonstrate that acetaldehyde induces tyrosine phosphorylation and disrupts tight junction and adherens junction in human colonic mucosa, which can be prevented by EGF and glutamine.

Acetaldehyde↗
PubMed1986

Morphological and biochemical changes of the pancreas in rats treated with acetaldehyde.

Daily intraperitoneal injections of acetaldehyde for 10 days to adult rats produced distinct morphological and biochemical changes in the exocrine pancreas, without affecting the body weight, pancreatic weight, and DNA, RNA, and protein content of the pancreas. By electronmicroscopy, although the number and size of the acinar zymogen granules appeared to be the same between the saline- and acetaldehyde-treated rats, the zymogen granules of the latter group showed decreased osmiophilia. Acinar mitochondria of the acetaldehyde-treated rats were found to be slightly swollen with dense granules, and plasma membrane fragments were often seen in the acinar lumen. Administration of acetaldehyde significantly decreased immunoreactive cationic trypsin (ogen) and total amylase activity in the pancreas, but not in the serum, where amylase activity was markedly increased. Basal secretion of amylase, trypsinogen, and chymotrypsinogen from isolated dispersed pancreatic acini of acetaldehyde-treated rats was increased by 40-50%. Nicotine (5-25 mM) induced a profound increase in secretion of the same enzymes from isolated acini of both saline- and acetaldehyde-treated rats, but in the latter group there was a concomitant rise in LDH release. Furthermore, CCK-8 (1 nM), secretin (1 microM), and carbachol (10 microM) either alone or in combination with nicotine (12.5 mM) produced a profound stimulation in amylase, trypsinogen, and chymotrypsinogen secretion from acini of both groups of rats. On the other hand, secretion of 3H-pulse-labeled proteins from isolated acini of acetaldehyde-treated rats by nicotine was decreased by approximately 50% compared with the controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetaldehyde↗
PubMed1986

Acetaldehyde adducts with serum proteins: effect on diazepam and phenytoin binding.

The in vitro effects of acetaldehyde treatment on the binding of phenytoin and diazepam to human serum albumin (HSA) and human serum proteins (HSP) have been investigated. The incorporation of acetaldehyde into proteins following incubation with different concentrations of [1,2-14 C]-acetaldehyde (0.5, 25, 100 mmol/l) was carried out. The proteins were then dialyzed so that only the stable adduct was retained. Binding of phenytoin and diazepam was then studied. Scatchard plot analysis showed a slight decrease (p less than 0.01 for HSP and 25 mmol/l acetaldehyde) in the number of binding sites for phenytoin when the acetaldehyde/protein ratio was increased. The affinity constant was also increased (p less than 0.01) with 100 mmol/l acetaldehyde. No change could be demonstrated in the number of diazepam binding sites on HSA; an increase in the binding capacity of HSP was shown following incubation with 25 mmol/l acetaldehyde. The fraction of drug bound at therapeutic levels has been also calculated for both drugs. An increase for diazepam but no change for phenytoin can be observed before or after treatment of proteins with acetaldehyde.

Acetaldehyde↗
PubMed1993

Aerosolized acetaldehyde induces histamine-mediated bronchoconstriction in asthmatics.

It has been reported that acetaldehyde may be a main factor of alcohol-induced bronchoconstriction in Japanese patients with asthma. The purpose of this study was to investigate the direct action of acetaldehyde on the airway in asthmatic and healthy nonasthmatic subjects. We investigated the bronchial response to inhalation of ascending doses (5, 10, 20, and 40 mg/ml) of acetaldehyde in nine asthmatic subjects, who were treated with placebo or terfenadine for 4 days in a double-blind, randomized, placebo-controlled, crossover fashion, and in nine age- and sex-matched healthy subjects. The bronchial responsiveness to inhaled methacholine was also measured in the same asthmatics on a separate day. Inhaled acetaldehyde caused marked (more than 20%) significant decrease in FEV1 in asthmatics after placebo, which was larger than that in asthmatics after terfenadine and in healthy subjects. There was no significant difference in the decrease in FEV1 between asthmatics treated with terfenadine and healthy subjects. There was a significant correlation between the methacholine and acetaldehyde concentrations producing a 20% fall in FEV1 in asthmatics. We conclude that acetaldehyde causes bronchoconstriction indirectly via histamine release in asthmatics, and that nonspecific bronchial hyperresponsiveness is a necessary precondition for the expression of acetaldehyde-produced bronchoconstriction.

Acetaldehyde↗
PubMed1998

[Effect of liver hydrolysate on ethanol- and acetaldehyde-induced deficiencies].

Since it has been reported that amino acids have alleviating effects on ethanol- and acetaldehyde-induced toxicity, we investigated the effect of liver hydrolysate derived from bovine liver on ethanol- or acetaldehyde-induced toxicity and deficiency models of mice and rats in the present study. Liver hydrolysate improved the deficiencies of beam walking and food intake of mice in a dose-dependent fashion when challenged with ethanol at the dose of 5 ml/kg, p.o. According to the analysis using selective inhibitors for alcohol dehydrogenase and acetaldehyde dehydrogenase, it has been suggested that this improvement effect of liver hydrolysate is mainly due to the reduction of acetaldehyde toxicity. No effect of liver hydrolysate was found in coma and death produced by orally treated ethanol at 10 ml/kg. In contrast, liver hydrolysate dose-dependently decreased the coma and death of mice administered acetaldehyde at 1.8 ml/kg, p.o. Furthermore, an increase in serum GPT activity, which was caused by twice oral administration of acetaldehyde at 1.2 ml/kg at interval of 1 hr, was inhibited by liver hydrolysate. These results suggest that liver hydrolysate has a protective effect against ethanol- and acetaldehyde-induced toxicity.

Acetaldehyde↗
PubMed1994

Inhibitory effect of a selective thromboxane synthetase inhibitor, OKY-046, on acetaldehyde-induced bronchoconstriction in asthmatic patients.

We recently reported that inhaled acetaldehyde causes bronchoconstriction indirectly via histamine release in patients with asthma. The purpose of this study was to investigate a role of thromboxane A2 in acetaldehyde-induced bronchoconstriction in asthmatic airways. We investigated the bronchial response to inhalation of ascending doses (5, 10, 20, and 40 mg/ml) of acetaldehyde in nine asthmatic subjects who were treated with placebo or OKY-046, a selective thromboxane A2 synthetase inhibitor, of 200 mg twice a day for 3 days, and 200 mg on the fourth day (test day) in a double-blind, randomized, placebo-controlled, crossover fashion. Percentage decreases in FEV1 caused by 20 and 40 mg/ml of acetaldehyde inhalation were significantly (p < 0.05 and p < 0.01, respectively) prevented by the pretreatment with OKY-046. Geometric mean value (geometric standard error of the mean) of acetaldehyde concentration producing a 20 percent fall in FEV1 (PC20-Ac-CHO) was significantly (p < 0.01) greater with the OKY-046 pretreatment (72.2 [1.1] mg/ml) than with the placebo pretreatment (19.8 [1.2] mg/ml). We conclude that thromboxane A2 is one of contributors to acetaldehyde-induced bronchoconstriction in asthmatic subjects. It suggests that thromboxane A2 may play an important role in endogenous histamine-induced bronchoconstriction caused by acetaldehyde in asthmatic airways. We believe that this is a first report on the interaction between endogenous histamine and thromboxane A2 in asthmatic subjects.

Acetaldehyde↗
PubMed2007

Susceptibility to inhalation toxicity of acetaldehyde in Aldh2 knockout mice.

In this study, we evaluated the inhalation toxicity of acetaldehyde in Aldh2 KO (Aldh -/-) mice, using pathological method. Male C57BL/6 (Aldh2 +/+) mice and Aldh -/- mice were exposed to atmospheres containing acetaldehyde at levels of 0, 125, and 500 ppm for 24 h/day during 14 days. Although the average blood acetaldehyde concentration of Aldh -/- mice was higher than that of Aldh2 +/+ mice in the acetaldehyde exposure group, observable effects by the acetaldehyde exposure on the lung and liver were not different between wild type and ALDH2 null mice. In Aldh2 -/- mice, the levels of 1) erosion of respiratory epithelium and the subepithelial hemorrhage in nose, 2) hemorrhage in nasal cavity, 3) degeneration of respiratory epithelium in larynx, pharynx and trachea, and 4) degeneration of dorsal skin were higher compared with Aldh2 +/+ mice, indicating that Aldh2 -/- mice are more acetaldehyde-sensitive than Aldh2 +/+ mice. This is the first example for studying pathological effects of Aldh2 deficiency using Aldh -/- mice exposed to a low level of acetaldehyde.

Acetaldehyde↗
PubMed1999

Acetaldehyde enhances murine alpha2(I) collagen promoter activity by Ca2+-independent protein kinase C activation in cultured rat hepatic stellate cells.

Protein kinase C (PKC) inhibitors decrease alpha1(I) collagen mRNA in stellate cells exposed to 200 micromol/liter of acetaldehyde. The purpose of these studies was to determine whether PKC activation plays a role in transcriptional activation of the alpha2(I) collagen gene. Cultured stellate cells were exposed to 200 micromol/liter of acetaldehyde. PKC, inositol triphosphate, diacylglycerol (DAG), and intracellular free calcium (Ca2+i) were measured. Alpha1(I) and alpha2(I) collagen messages were determined by reverse transcriptase-polymerase chain reaction. Activation of the alpha2(I) collagen promoter was determined in transiently transfected stellate cells. Acetaldehyde exposure enhanced PKC activity translocation to the particulate fraction at 20 min. Acetaldehyde did not increase Ca2+i, or inositol triphosphate but increased DAG levels at 20 min and 3 hr. Acetaldehyde increased both the alpha1(I) and alpha2(I) collagen messages in stellate cells. Calphostin C, a specific PKC inhibitor, which blocks DAG binding, eliminated both activation of the alpha2(I) collagen promoter by acetaldehyde and mRNA production by reverse transcriptase-polymerase chain reaction analysis. Similarly, D609, an inhibitor of DAG production, also inhibited alpha2(I) collagen gene expression. This study shows that collagen production by acetaldehyde is mediated by a calcium-independent PKC mechanism.

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PubMed2000

Metronidazole increases intracolonic but not peripheral blood acetaldehyde in chronic ethanol-treated rats.

BACKGROUND: Metronidazole leads to the overgrowth of aerobic flora in the large intestine by reducing the number of anaerobes. According to our previous studies, this shift may increase intracolonic bacterial acetaldehyde formation if ethanol is present. Metronidazole is also reported to cause disulfiram-like effects after alcohol intake, although the mechanism behind this is obscure. Therefore, the aim was to study the effect of long-term metronidazole and alcohol treatment on intracolonic acetaldehyde levels and to explore the possible role of intestinal bacteria in the metronidazole related disulfiram-like reaction. METHODS: A total of 32 rats were divided into four groups: controls (n = 6), controls receiving metronidazole (n = 6), ethanol group (n = 10), and ethanol and metronidazole group (n = 10). All rats were pair-fed with the liquid diet for 6-weeks, whereafter blood and intracolonic acetaldehyde levels and liver and colonic mucosal alcohol (ADH) and aldehyde dehydrogenase (ALDH) activities were analyzed. RESULTS: The rats receiving ethanol and metronidazole had five times higher intracolonic acetaldehyde levels than the rats receiving only ethanol (431.4 +/- 163.5 microM vs. 84.7 +/- 14.4 microM,p = 0.0035). In contrast, blood acetaldehyde levels were equal. Cecal cultures showed the increased growth of Enterobacteriaceae in the metronidazole groups. Metronidazole had no inhibitory effect on hepatic or colonic mucosal ADH and ALDH activities. CONCLUSIONS: The increase in intracolonic acetaldehyde after metronidazole treatment is probably due to the replacement of intestinal anaerobes by ADH-containing aerobes. Unlike disulfiram, metronidazole neither inhibits liver ALDH nor increases blood acetaldehyde. Thus, our findings suggested that the mechanism behind metronidazole related disulfiram-like reaction might be located in the gut flora instead of the liver.

Acetaldehyde↗
PubMed2001

Acetaldehyde adducts in blood and bone marrow of patients with ethanol-induced erythrocyte abnormalities.

BACKGROUND: Although alcohol abuse is known to cause a wide array of adverse effects on blood cell formation, the molecular mechanisms by which alcohol exerts its toxic actions remain poorly defined. We examine here the formation of acetaldehyde-derived protein modifications in erythrocytes and in their bone marrow precursors using antibodies specifically recognizing acetaldehyde-modified epitopes in proteins independently of the nature of the carrier protein. MATERIALS AND METHODS: We studied 138 consecutive adult patients undergoing bone marrow aspiration due to macrocytosis (MCV values above 99 fL). Assessment included complete blood counts, morphologic review, assessment of alcohol consumption, and biochemical and immunocytochemical assays for acetaldehyde adducts. RESULTS: There were 68 patients (49%) with a history of excessive alcohol consumption, 28 (20%) of whom were patients with severe dependence. The blood smears prepared from the alcoholic patients with macrocytosis also contained stomatocytes and knizocytes. Bone marrow aspirates from 12 alcoholic patients showed vacuolization of pronormoblasts and the presence of ring sideroblasts was noted in 8 cases. In immunocytochemical analyses of the peripheral blood erythrocytes, acetaldehyde-derived epitopes were found to occur both on the cell membrane and inside the erythrocytes. Bone marrow aspirates also showed positive staining for acetaldehyde adducts in the erythropoietic cells in 8 of 11 (73%) consecutive alcoholic patients. Separation of the erythrocyte proteins from the samples of alcoholics on HPLC-chromatography revealed the formation of fast-eluting hemoglobin fractions, which also reacted with antibodies against acetaldehyde adducts. CONCLUSIONS: Current data suggest that acetaldehyde-erythrocyte adducts are formed in vivo in blood and bone marrow of patients with excessive alcohol consumption. This may contribute to the generation of the erythrocyte abnormalities, which are frequently observed in alcoholic patients.

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PubMed1992

Method of acetaldehyde measurement with minimal artifactual formation in red blood cells and plasma of actively drinking subjects with alcoholism.

After alcohol consumption, a substantial amount of acetaldehyde that is reversibly bound to protein and nonprotein components of the red blood cells circulates in the blood and could cause extrahepatic toxicity. However, acetaldehyde measurement in human red blood cells is hampered by considerable ex vivo artifactual formation as a result of nonenzymatic oxidation of ethanol during protein precipitation. To eliminate this source of artifactual formation, free and reversibly bound acetaldehyde were trapped with semicarbazide from red blood cell hemolysates, and both the stroma and the hemoglobin were sequentially removed by centrifugation and ion-exchange chromatography in carboxymethyl Sephadex, respectively. The eluted semi-carbazone was dissociated with perchloric acid, and the acetaldehyde that was released in the protein-free supernatants was measured by head-space gas chromatography. Maximal retention of hemoglobin by carboxymethyl Sephadex and complete recovery of acetaldehyde and ethanol were achieved at a pH of 5.3. The artifactual formation decreased from 2.62 +/- 0.32 mumol of acetaldehyde per millimole of ethanol in the initial hemolysates to 1.38 +/- 0.20 mumol after removal of the stroma and to a level that is comparable to measurements in plasma (0.09 +/- 0.02 mumol) after removal of both the stroma and the hemoglobin. In 12 actively drinking subjects with alcoholism, with blood ethanol levels that ranged between 9 and 81 mmol/L, the concentrations of acetaldehyde in red blood cells (11.50 +/- 1.46 mumol/L; range: 7.5 to 22 mumol/L) were minimally affected by blood ethanol levels and were three times as high as those in the plasma (3.74 +/- 1.49 mumol/L).(ABSTRACT TRUNCATED AT 250 WORDS)

Acetaldehyde↗