Blood Acetaldehyde Levels Research Articles

Disulfiram and erythrocyte aldehyde dehydrogenase inhibition.

During disulfiram therapy erythrocyte aldehyde dehydrogenase (ALDH) was fully inhibited. The time for total loss of erythrocyte ALDH activity ranged from 36 to 120 hr. In contrast to the 85% recovery of in vitro disulfiram-inhibited ALDH activity, this in vivo disulfiram-ALDH inhibition could not be reversed by mercaptoethanol. It is proposed that the in vivo and in vitro mechanisms of ALDH inhibition by disulfiram differ. Erythrocyte ALDH activity can be readily monitored to determine patient compliance and is an accessible model for investigations of in vivo mechanisms of drug inhibition. Because the disulfiram-inhibited erythrocyte ALDH is not regenerated until new erythrocytes are made (120 days), a significant portion of the extrahepatic acetaldehyde metabolic capacity remains inhibited for long periods after disulfiram is discontinued. Thus, the recidivistic patient who discontinues disulfiram and waits several days (to regenerate liver ALDH activity) before drinking will be exposed to even higher ethanol-derived blood acetaldehyde levels than usual, which may induce further alcohol-associated organ damage and alcohol dependence.

Some teratogenic properties of ethanol and acetaldehyde in C57BL/6J mice: implications for the study of the fetal alcohol syndrome.

To investigate the teratogenic effect of acute alcohol exposure, pregnant C57BL/6J mice were exposed to 25% ethanol (either two doses of 2.9g/kg or one dose 5.8g/kg) during the organogenic period either by intraperitoneal injections or by intubation. The incidence of malformations varied according to (1) the stage of embryonic development at the time of exposure, (2) the route of administration of the alcohol, and (3) the amount of alcohol given and the time period over which it was administered. Oral doses of alcohol were teratogenic although less so than the same dose given intraperitoneally, and two intraperitoneal doses four hours apart produced significantly more malformation than the same two doses six hours apart. The primary metabolite of alcohol, acetaldehyde, was also investigated for its teratogenicity. It was found that one or two doses of four percent acetaldehyde (0.32g/kg), administered intraperitoneally were teratogenic. A further attempt was made to raise blood acetaldehyde levels by exposing mice to disulfiram, an inhibitor of acetaldehyde dehydrogenase, prior to administration of alcohol. The disulfiram pretreatment did not increase the malformation rate. Treatment with alcohol on day 7 or 8 caused a variety of facial abnormalities, some of which were comparable to those seen in children with fetal alcohol syndrome. Exposure on day 9 or 10 resulted in limb defects. The results suggest that one or more episodes of heavy maternal drinking at critical periods in pregnancy may severely damage the embryo and may produce many features of the fetal alcohol syndrome.

Determinants of Blood Acetaldehyde Level during Ethanol Oxidation in Chronic Alcoholics

We analyzed the blood alcohol and acetaldehyde concentrations in nine alcoholics and four healthy nonalcoholic controls during and after an intravenous infusion of a high and a low dose of alcohol. In the alcoholics, the mean rates of plasma ethanol disappearance were significantly higher than in nonalcoholic controls. In the control subjects, the blood acetaldehyde levels were, in general, below the detection limit (less than 0.5 microM), but in sharp contrast to this, an elevated blood acetaldehyde during ethanol infusion was found in 6/9 alcoholics. Peak blood acetaldehyde values were higher after the high than the low dose of alcohol. Fructose infusion significantly enhanced the rate of plasma ethanol disappearance both in controls and in alcoholics, and this was usually associated with a significant elevation of blood acetaldehyde level. The maximal specific activities (expressed as milliunits/mg og protein) of alcohol, lactate, and aldehyde dehydrogenases in liver were significantly lower in alcoholics than in controls. Even more importantly, the peak blood acetaldehyde correlated negatively with the activity of hepatic "low-Km" aldehyde dehydrogenase. Our results suggest that the main reason for blood acetaldehyde elevation seen in these chronic alcoholics is their impaired capacity to metabolize acetaldehyde. This may be further accentuated by the increased rate of ethanol oxidation.

Inhibition of testosterone biosynthesis by ethanol. Relation to hepatic and testicular acetaldehyde, ketone bodies and cytosolic redox state in rats.

In experiments in which liver and testis freeze-stops were performed on pentobarbital-anaesthetized rats, ethanol (1.5 g/kg body wt.) reduced plasma testosterone concentration from 13.1 to 3.2 nmol/litre. 4-Methylpyrazole abolished the ethanol-induced hepatic and testicular increase in the lactate/pyruvate ratio, and the testicular acetaldehyde level, but did not diminish the reduction in plasma testosterone concentration. In testes, but not in liver, ethanol decreased the 3-hydroxybutyrate/acetoacetate ratio, and 4-methylpyrazole did not prevent this effect. In experiments in which freeze-stop was performed after cervical dislocation, ethanol decreased the testis testosterone concentration from 590 to 220 pmol per g wet wt. The effects of ethanol and 4-methylpyrazole on testis acetaldehyde, lactate/pyruvate and 3-hydroxybutyrate/acetoacetate ratios were the same as found during anaesthesia. The NAD+-dependent ethanol oxidation capacity in testis ranged from 0.1 to 0.2 mumol/min per g wet wt. and seemed to be inhibited by 4-methylpyrazole both in vivo and in vitro. In additional experiments, ethanol doses between 0.3 and 0.9 g/kg body wt. did not alter the plasma testosterone concentration in rats treated, or not treated, with cyanamide, which induced elevated acetaldehyde levels in blood and testes. The results suggest that ethanol-induced inhibition of testosterone biosynthesis was not caused by extratesticular redox increases, or by extra- or intra-testicular acetaldehyde per se. The inhibition is accompanied by changes in testicular ketone-body metabolism.

Blood ethanol and acetaldehyde levels in Japanese alcoholics and controls

Aldehyde dehydrogenase (ALDH) isozyme I deficiency in hair root samples from 105 healthy individuals and 72 alcoholics was determined using isoelectric focusing. From these individuals, 12 male alcoholics (2 with ALDH isozyme I deficiency and 10 normal) and 45 healthy controls (18 with ALDH isozyme I deficiency and 27 normal) were investigated for their blood ethanol and acetaldehyde levels by gas chromatography after an acute dose of alcohol (0.5 g ethanol/kg body wt.). Peak blood ethanol values of about 10 mmol/l were attained after 1 hour both in alcoholics and normal controls irrespective of their ALDH type. There was no significant difference in the blood ethanol level during the 5 hr post-drinking period in both the groups. Peak blood acetaldehyde concentration was significantly higher in healthy controls and alcoholics deficient in ALDH isozyme I after alcohol drinking (about 30 μmmol/l) than in individuals with normal ALDH isozyme I (3 μmmol/l). However, no significant difference in blood acetaldehyde was observed between alcoholics and controls.

Acetaldehyde-mediated alcohol sensitivity and elevation of plasma catecholamine in man.

According to the presence and absence of aldehyde dehydrogenase (ALDH) I isozyme which had low Km for acetaldehyde, subjects were divided into two groups: the former, the usual ALDH group and the latter, the unusual ALDH one. Blood alcohol and acetaldehyde levels, plasma norepinephrine and epinephrine levels, and urinary excretion of norepinephrine, epinephrine, dopamine, vanillylmandelic acid (VMA) and 3-methoxy-4-hydroxyphenylglycol (MHPG) were determined; and the differences in these values and cardiovascular symptoms after alcohol intake between the two groups were investigated. Fifty-six healthy male volunteers were studied after they ingested 0.4 g of alcohol per kg of body weight. There was no difference in blood alcohol level between the two groups. In the unusual ALDH group, facial flushing, increase of pulse rate and decrease in diastolic blood pressure associated with accumulation of blood acetaldehyde were shown. In addition, rises in plasma catecholamine and urinary excretion of catecholamine were also observed. However, in the usual ALDH group, in which blood acetaldehyde level scarcely increased, these changes were not significant. The alteration of catecholamine metabolism, decrease in urinary VMA and increase in urinary MHPG was recognized in both groups.

ACETALDEHYDE-MEDIATED ALCOHOL SENSITIVITY AND ELEVATION OF PLASMA CATECHOLAMINE IN MAN

According to the presence and absence of aldehyde dehydrogenase (ALDH)I isozyme which had low Km for acetaldehyde, subjects were divided into two groups:the former, the usual ALDH group and the latter, the unusual ALDH one. Blood alcohol and acetaldehyde levels, plasma norepinephrine and epinephrine levels, and urinary excretion of norepinephrine, epinephrine, dopamine, vanillylmandelic acid (VMA) and 3-methoxy-4-hydroxyphenylgIycol (MHPG) were determined; and the differences in these values and cardiovascular symptoms after alcohol intake between the two groups were investigated. Fifty-six healthy male volunteers were studied after they ingested 0.4 g of alcohol per kg of body weight. There was no difference in blood alcohol level between the two groups. In the unusual ALDH group, facial flushing, increase of pulse rate and decrease in diastolic blood pressure associated with accumulation of blood acetaldehyde were shown. In addition, rises in plasma catecholamine and urinary excretion of catecholamine were also observed. However, in the usual ALDH group, in which blood acetaldehyde level scarcely increased, these changes were not significant.The alteration of catecholamine metabolism, decrease in urinary VMA and increase in urinary MHPG was recognized in both groups.

Effects of cephem antibiotics on rat liver aldehyde dehydrogenases.

Effects of cephem antibiotics, which have a tetrazolethiol side chain, on rat liver mitochondrial aldehyde dehydrogenases (ALDH) were investigated in vitro and in vivo. The antibiotics tested were cefmetazole (CMZ), cefamandole (CMD), cefotiam (CTM), cefoperazone (CPZ) and latamoxef (LMOX). The antibiotics inhibited low-Km ALDH activity by 17-30% at 5 mM in vitro. The degrees of inhibition were in the order: CMZ = CTM = CMD greater than LMOX greater than CPZ. Disulfiram inhibited the enzyme activity by 50% at approx. 40 microM. The antibiotics (except CTM) at a dose of 1,000 mg/kg i.v. inhibited the low-Km ALDH activity by 36-52% of the control 24 hr after pretreatment, but did not alter the high-Km ALDH activity. The degrees of inhibition were in the order: LMOX = CMD greater than CPZ greater than CMZ. Disulfiram at a dose of 300 mg/kg p.o. markedly inhibited the low-Km ALDH activity, but did not alter the high-Km ALDH activity. The blood acetaldehyde levels during ethanol metabolism were elevated 1.3-2.6 times in rats treated with the cephem antibiotics (except CTM) for 24 hr at a dose of 1,000 mg/kg i.v. The degrees of elevation at 1 hr after ethanol injection were in the order: LMOX greater than CMD greater than CPZ greater than CMZ. The present experiments demonstrated that the rise in blood acetaldehyde levels coincided with the inhibition rates of the low-Km ALDH activity by the cephem antibiotics.

EFFECTS OF CEPHEM ANTIBIOTICS ON RAT LIVER ALDEHYDE DEHYDROGENASES

Effects of cephem antibiotics, which have a tetrazolethiol side chain, on rat liver mitochondrial aldehyde dehydrogenases (ALDH) were investigated in vitro and in vivo. The antibiotics tested were cefmetazole (CMZ), cefamandole (CMD), cefotiam (CTM), cefoperazone (CPZ) and latamoxef (LMOX). The antibiotics inhibited low-Km ALDH activity by 17-30% at 5 mM in vitro. The degrees of inhibition were in the order: CMZ=CTM=CMD>LMOX>CPZ. Disulfiram inhibited the enzyme activity by 50% at approx. 40 μM. The antibiotics (except CTM) at a dose of 1,000 mg/kg i.v. inhibited the low-Km ALDH activity by 36-52% of the control 24 hr after pretreatment. but did not alter the high-Km ALDH activity. The degrees of inhibition were in the order: LMOX= CMD>CPZ>CMZ. Disulfiram at a dose of 300 mg/kg p.o. markedly inhibited the low-Km ALDH activity, but did not alter the high-Km ALDH activity. The blood acetaldehyde levels during ethanol metabolism were elevated 1.3-2.6 times in rats treated with the cephem antibiotics (except CTM) for 24 hr at a dose of 1.000 mg/kg i.v. The degrees of elevation at 1 hr after ethanol injection were in the order: LMOX>CMD>CPZ>CMZ. The present experiments demonstrated that the rise in blood acetaldehyde levels coincided with the inhibition rates of the low-Km ALDH activity by the cephem antibiotics.

Human blood acetaldehyde concentration during ethanol oxidation (update 1982)

A wide variety of levels of human blood acetaldehyde have been reported in the past. During the last few years, however, it has become increasingly evident that most, if not all, of the previously observed acetaldehyde concentrations during normal (i.e., no deficiency in, or inhibition of, aldehyde dehydrogenase activity) ethanol oxidation merely reflected artefactual acetaldehyde formed during the analytical procedures. The artefactual acetaldehyde formation, which occurs mainly during blood protein precipitation, is effectively minimized by the recently improved PCA method in which blood is immediately mixed with a perchloric acid-saline solution, and by the semicarbazide method in which blood is treated with a fresh isotonic semicarbazide solution before removal of the plasma. Nevertheless, a procedure involving control blood with ethanol added should be employed to control for any artefactual acetaldehyde still produced. Based on the improved analytical procedures, no detectable acetaldehyde was found in the venous blood of Caucasian subjects after acute ethanol intake.

Plasma chlorpropamide: a critical factor in chlorpropamide-alcohol flush.

The chlorpropamide-alcohol flush (CPAF) phenomenon was quantitatively related to blood levels of acetaldehyde and chlorpropamide in 105 Type II diabetics, of whom 74 had not previously taken the drug and 31 were on chronic treatment. Standardized skin temperature recordings were made with a sensitive probe. Plasma ethanol and acetaldehyde concentrations were determined by gas chromatography, and those of chlorpropamide by high-pressure liquid chromatography. There were significant positive correlations between plasma acetaldehyde and the skin temperature increase, between plasma chlorpropamide and plasma acetaldehyde, and between plasma chlorpropamide and the skin temperature increase. CPAF-positive patients became CPAF-negative and vice versa following reduction and increase, respectively, in the dose of chlorpropamide. Thus, the CPAF reaction is a consequence of chlorpropamide inhibition of the oxidation of ethanol-generated acetaldehyde, and it appears that the plasma concentration of chlorpropamide is critical. It remains an open question whether the CPAF test has any prognostic value.

Human Blood Acetaldehyde Levels: With Improved Methods, a Clearer Picture Emerges

New reliable methods for the determination of acetaldehyde in human blood, either from separated plasma or from acid-precipitated whole blood, demonstrate that the blood of healthy Caucasians contains at most only extremely small amounts of acetaldehyde (less than 1 microM) after moderate alcohol intoxication. On the other hand, among about 50% of the Japanese population ethanol ingestion results in elevated blood acetaldehyde levels (10-50 microM) with consequent unpleasant cardiovascular responses such as facial flushing and tachycardia, apparently because of a lack of one of the acetaldehyde-oxidizing aldehyde dehydrogenase isozymes. Elevated acetaldehyde levels may eventually occur also among intoxicated Caucasian alcoholics, primarily as a consequence of abuse-induced loss of hepatic aldehyde dehydrogenase activity, but accentuated by an accelerated ethanol oxidation rate. The elevation is probably reversible, since no acetaldehyde is seen in alcoholics after abstinence and hospital treatment. There is thus little evidence that an elevation of acetaldehyde could serve as a marker for predisposition for alcoholism.

The polymorphisms of alcohol and aldehyde dehydrogenase and their significance for acetaldehyde toxicity

Evidence is growing that acetaldehyde is responsible for some toxic effects after ethanol intake. Large individual and racial differences in blood and breath acetaldehyde concentrations are observed after alcohol consumption. In many Orientals but few Caucasians extremely high blood acetaldehyde levels occur leading to an acute aldehyde syndrome also observed after treatment with aldehyde dehydrogenase inhibitors. Individuals suffering from the aversive symptoms of that syndrome will be protected from excessive drinking and the related problems. In chronic aldehydism slightly elevated aldehyde concentrations are observed possibly leading to organic injury due to the cytotoxic action of acetaldehyde. Sites exhibiting high alcohol dehydrogenase activity may specifically be affected in alcoholics.

Metabolic activation of cyanamide to an inhibitor of aldehyde dehydrogenase in vitro

The inhibition of aldehyde dehydrogenase (AlDH) by cyanamide is dependent on the conversion of the latter to an active metabolite. This accounts for the in vivo activity of cyanamide in raising ethanol-derived blood acetaldehyde levels to the mM range in the rat (ED 50 for cyanamide=0.11 mmole/kg) and its lasc of inhibitory activity in vitro with purified AlDH enzymes. Liver mitochondria were shown to catalyze this activation. The Low K m mitochondrial AIDH isozyme was strongly inhibited by cyanamide when measured in intact rat liver mitochondria (I 50=2.0 μM). Cyanamide also inhibited yeast AlDH when incubated in the presence, but not in the absence, of rat liver mitochondria (I 50=7.8 μM). Using yeast AIDH activity as a measure of cyanamide activation, the subcellular distribution of the cyanamide-activating system was assessed. Microsomes plus an NADPH generating system were equally active as mitochondria in activating cyanamide. In the absence of NADPH, microsomal activity was about half that of mitochondria. Little or no activity was found in the cytosolic fraction. A series of cyanamide analogs and derivatives were screened for their ability to inhibit the low K m AlDH isozyme measured in intact mitochondria. Only monoalkylcyanamides exemplified by n-butylcyanamide showed significatn inhibition. Other cyanamide analogs and derivatives including N-acetylcyanamide, the major urinary metabolite of cyanamide, were inactive in this system.

Acute effects of ethanol and acetaldehyde on blood pressure and heart rate in disulfiram-treated and control rats.

The cardiovascular effects of ethanol and acetaldehyde were studied in control rats and rats pretreated with disulfiram. Ethanol administration to control rats decreased mean blood pressure and increased heart rate significantly. Injection of ethanol to disulfiram-treated rats decreased mean blood pressure, increases pulse pressure and increased heart rate and respiratory rate. The blood acetaldehyde levels were 10-15 times higher than those found in controls. The effects evoked by ethanol in disulfiram-treated rats were prevented or abolished in rats given 4-methylpyrazole before or after ethanol. Heart rate increased with increasing concentrations of acetaldehyde in control rats given acetaldehyde intravenously. Only a slight decrease in mean blood pressure was seen at high acetaldehyde levels (150-250 microM), whereas pulse pressure increased markedly as well as respiratory rate. At acetaldehyde levels lower than 50 microM, no effects on blood pressure were seen. The effects of acetaldehyde infusion in disulfiram-treated rats were similar to those observed in controls having comparable acetaldehyde levels. The results suggest that the disulfiram-ethanol reaction in rats is caused by the combined action of ethanol and acetaldehyde on the cardiovascular system.

A change in susceptibility of rat cerebellar Purkinje cells to damage by acetaldehyde during fetal, neonatal and adult life.

Phillips S.C. & Cragg B.G. 1982 Neuropathology a id Applied Neurobiology 8, 455–463A change in susceptibility of rat cerebellar Purkinje cells to damage by acetaldehyde during fetal neonatal and adult lifeThe sensitivity of rat cerebellar Purkinje cells to acetaldehyde during fetal, neonatal or adult life has been assessed by histological techniques. A pregnant female rat was exposed to ethanol vapour during the last 2 weeks of gestation while metabolism of acetaldehyde was blocked by injections of disulfiram (200mg/kg) on days E14, E16, E18 and E20. Purkinje cells were counted in the offspring 5 days after birth. The number of Purkinje cells in lobes I and VIII were 52% and 42% less than age matched controls. Smaller reductions were found in lobes V and X. The weight of the cerebellum was reduced by 42%. Neonatal rats received disulfiram (40mg) on the second day after birth and were exposed to ethanol vapour during daylight hours on the third and fourth days. Purkinje cells were counted at 5 days after birth, and losses similar to those described above were found. The weight of the cerebellum was reduced by 47%. Adult male rats were exposed to ethanol vapour for 2 weeks and given disulfiram (200mg/kg) on every second day. No reduction in cerebellar weight or loss of Purkinje cells was detected. When the dura overlying the cerebellum in adult rats was superfused with acetaldehyde solutions for 1 h, a 1–6 M solution caused degeneration whereas a 0–68 M solution did not. Thus the combination of high blood ethanol and acetaldehyde levels is damaging to perinatal Purkinje cells, whereas adult cells are resistant. We found the same ranking of susceptibility with ethanol alone (Philips & Cragg, 1982a and it was surprising that the cell losses with acetaldehyde were only marginally greater than those with ethanol alone, in view of the greater neurotoxicity of acetaldehyde during acute exposure (Phillips, 1981.

Effects of dopamine-beta-hydroxylase inhibitors FLA-57 and FLA-63 on ethanol metabolism and aldehyde dehydrogenase activity in rats.

In rats pretreated with the dopamine-beta-hydroxylase (DBH)-inhibitors FLA-57 and FLA-63 (60 mg/kg, intraperitoneally, for 4 and 18 hrs), no effects on the blood acetaldehyde level after ethanol administration or on the activity of the low-Km aldehyde dehydrogenase (ALDH) in the liver were found. FLA-63 but not FLA-57 decreased the rate of ethanol elimination. FLA-63 inhibited the low-Km enzyme in vitro, but much less than the ALDH-inhibitors disulfiram and cyanamide. FLA-57 caused no inhibition in vitro. The results show that the previously observed suppression of ethanol intake in rats by FLA-57 and FLA-63 was not caused by an acetaldehyde-mediated aversion such as during the disulfiram-ethanol reaction.

Impaired acetaldehyde oxidation in alcoholics.

High blood acetaldehyde levels in alcoholics after ethanol ingestion are due to reduced acetaldehyde oxidation rather than to an increased rate of its formation from ethanol. This is associated with low hepatic acetaldehyde dehydrogenase activity in alcoholic subjects and may represent a specific abnormality in them.

Increase of plasma acetaldehyde. An objective indicator of the chlorpropamide alcohol flush.

Chlorpropamide alcohol flushing (CPAF) in non-insulin-dependent diabetics (NIDDs) has been reported to be associated with a lower tendency to develop late complications. The flush was thought to be mediated by enkephalins and prostaglandins. Early studies could not correlate CPAF to increased levels of acetaldehyde in blood and the flush was not regarded as an antabuse-like reaction. In this study, the increase of plasma acetaldehyde during the flush in 13 CPAF positive diabetics was significantly (P less than 0.005) higher than in the 13 CPAF negative diabetics during a CPAF challenge test. The increase of plasma acetaldehyde was reduced to the level of CPAF negative diabetics in three CPAF positive diabetics when they were exposed to alcohol without premedication with chlorpropamide and they did not flush. The normal breakdown of ethanol to acetic acid via acetaldehyde appears to be inhibited by chlorpropamide in the flushers. Acetaldehyde measurement is an objective method to study the chlorpropamide alcohol flush and it appears superior to the measurement of skin temperature.

Acetaldehyde penetrates the blood-liquor barrier of goats

Goats received ethanol or acetaldehyde via carotid arterial infusions. Cerebrospinal fluid (CSF) was sampled from a lateral cerebral ventricle and blood from a jugular vein. Ethanol infusions produced only negligible levels of acetaldehyde in blood and CSF, but acetaldehyde infusions resulted in high levels. In contrast to ethanol, acetaldehyde was rapidly eliminated from both blood and CSF after discontinuing the infusion. The results indicate that even small amounts of acetaldehyde easily penetrate the blood-liquor barrier of goats.