AGE-RELATED DIFFERENCES IN BLOOD ETHANOL PARAMETERS AND SUBJECTIVE FEELINGS OF INTOXICATION IN HEALTHY MEN

Healthy men within 4 age groups, 20–29, 30–39, 40–49and 50–59 years (N = 12 per group), drank 0.68 g/kg ethanolas neat whisky after fasting overnight. The drink was finishedwithin 20 min and the concentrations of ethanol in capillaryblood were determined at 30/60 min intervals for 7 hr. At thetime of blood sampling, the men were asked to estimate theirfeelings of intoxication according to an arbitrary scale onwhich the score 10 indicated ‘tipsy’ or a ‘Littlehigh’. The time course of blood ethanol concentrationwas similar in all 4 groups with the curve for 50–59-year-oldmen on the highest level and 20–29-year-old men lowest.Subjective intoxication scores were significantly less in theyoungest age group and the maximum score for each subject wascorrelated with age (r = 0.45, P << 0.01). Total bodywater (TBW) was not correlated with age directly (r = 0.17,P > 0.05) but when it was expressed as percent of body weighta strong negative correlation was found (r = –0.77, P> 0.001). The mean total body water estimated from ethanoldilution was 46.7 ± 4.11. (+ SD, N = 48) and this correspondsto 58% of mean body weight of the men. The distribution volumeof ethanol/kg body weight (V_d) decreased with ageing (r = –0.59,P < 0.001) being 0.72, 0.71, 0.68 and 0.66 l/kg on averagein the 20–29, 30–39, 40–49 and 50–59-year-oldage groups respectively. The reduction of V_d corresponds toan age-related decrease in the percentage of body water andan increase in the percentage of body fat. This results in elevatedblood ethanol concentrations in older individuals for a constantdose/kg body weight. The absorption of ethanol from the gutand its rate of disappearance from blood were not markedly influencedby age. The lower subjective feelings of intoxication reportedby younger men may indicate that age-related differences inacute functional tolerance to ethanol or different thresholdvalues of blood ethanol may exist before an effect is felt.     

Advanced glycation end-products in patients with chronic alcohol misuse

Aims: The aim of our study was to determine serum levels ofadvanced glycation end-products (AGE) in patients with chronicalcohol misuse and to examine their relationship to markersof nutrition and inflammation. Methods: The study group consistedof 23 heavy alcohol drinkers treated for chronic alcohol misuseand 22 healthy controls. Studied parameters included AGE (fluorescence,CML – carboxymethyllysine and pentosidine), lipids, glucose,albumin, leptin, prealbumin, C-reactive protein (CRP) and pregnancy-associatedplasma protein A (PAPP-A). Results: AGE fluorescence was significantlyhigher in chronic alcoholic patients than in healthy subjects(4.3 ± 0.7 x 10³ vs 3.7 ± 0.5 x 10³ AU/g protein,P < 0.005), while CML was only slightly but not significantlyelevated (569.1 ± 106.6 vs 545.5 ± 85.8 µg/l)and pentosidine levels did not differ (105.4 ± 29 vs102.2 ± 23 nmol/l). In alcoholics, AGE correlate significantlynegatively with leptin (r = –0.46, P < 0.05) and pentosidinewith prealbumin (r = –0.43, P < 0.05), otherwise therewas no relationship between AGE and other biochemical parameters(glucose, cholesterol, albumin, CRP, PAPP-A). Conclusion: Ourfindings suggest a more complex relationship among advancedglycation, oxidative stress and metabolism of ethanol and theirlink to nutrition and nutrition-associated parameters. AGE asa result of oxidative stress might be similarly linked to increasedcardiovascular risk of heavy alcohol drinkers, as are malnutritionand inflammation; however, further studies are needed to confirmthis hypothesis.     

RECOVERY AFTER INTERRUPTED EXPOSURE DURING INDUCTION OF EXPERIMENTAL ALCOHOLISM IN THE RAT

A model of alcoholism founded on a long-term treatment withintermittent weekly ethanol exposures [each week a voluntarychoice between 10% (w/v) ethanol and water for 24 hr followedby an intraperitoneal (i.p.) injection of 2.0 g/kg ethanol]was used to test the effect of a 10-week interruption of thetreatment. Three groups were tested. Group CT had 65 weeks oftreatment with no interruption. Group BT started the treatmentat the same time as group CT, but no treatment was given inweeks 33–42. In group LS, the treatment started at thesame time as it was restarted in group BT (week 43). An evaluationperiod with a continuous choice between ethanol and water wasstarted in week 66. During the evaluation period dependence,defined as a voluntary ethanol intake not influenced by changesin ethanol concentration, was determined by comparing the intakeof a 10% (w/v) reference solution with that of a 5% (w/v) testsolution. At the start of the treatment the 24 hr voluntaryethanol intake in group CT and BT was inhibited maximally after6–7 weeks of treatment. When group LS was started in week43, a similar, but more marked, inhibition developed. In allgroups, ethanol intake rose again after the inhibition. Afterrestarting the treatment in group BT, the rats could be dividedinto two subgroups. Group BT;LI with a low intake of ethanolin week 32 had voluntary ethanol intake after restarting thetreatment which was similar to corresponding data recorded ingroup LS when starting the treatment. In group BT;HI with ahigh intake of ethanol in week 32 there was no influence ofthe break in the treatment. The voluntary ethanol intake wassimilar to the corresponding intake in group CT and not to thatseen in group LS. During the evaluation period, a marked dependencewas recorded as a strong correlation between voluntary intakeof ethanol as a 5 and a 10% solution in group CT (r=0.93; N=11,P<0.001). A similar dependence but with a lower daily ethanolintake was recorded in group LS (r=0.88, N=9, P<0.01) aftera treatment lasting for 22 instead of 65 weeks. A dependencewas recorded in group BT;HI (r=0.97; N=4, P<0.05) but notin group BT;LI (r=0.63, N=7, NS). Thus rats with a low intakebefore the break of the treatment behaved as naïve ratsstarting the treatment but did not show dependence, while ratswith a high intake before the break behaved in the same wayas rats continuously exposed to ethanol with regard to the developmentof dependence.     

URINARY EXCRETION OF METHANOL AND 5-HYDROXYTRYPTOPHOL AS BIOCHEMICAL MARKERS OF RECENT DRINKING IN THE HANGOVER STATE

Twenty healthy social drinkers (9 women and 11 men) drank either50 g of ethanol (mean intake 0.75 g/kg) or 80 g (mean 1.07 g/kg)according to choice as white wine or export beer in the eveningover 2 h with a meal. After the end of drinking, at bedtime,in the following morning after waking-up, and on two furtheroccasions during the morning and early afternoon, breath-alcoholtests were performed and samples of urine were collected foranalysis of ethanol and methanol and the 5-hydroxytryptophol(5-HTOL) to 5-hydroxyindol-3-ylacetic acid (5-HIAA) ratio Theparticipants were also asked to quantify the intensity of hangoversymptoms (headache, nausea, anxiety, drowsiness, fatigue, muscleaches, vertigo) on a scale from 0 (no symptoms) to 5 (severesymptoms). The first morning urine void collected 6-11 h afterbedtime as a rule contained measurable amounts of ethanol, being0.09 ± 0.03 g/l (mean ± SD) after 50 g and 0.38± 0.1 g/l after 80 g ethanol. The corresponding breath-alcoholconcentrations were zero, except for three individuals who registered0.01–0.09 g/l. Ethanol was not measurable in urine samplescollected later in the morning and early afternoon. The peakurinary methanol occurred in the first morning void, when themean concentration after 80 g ethanol was {small tilde} 6-foldhigher than pre-drinking values. This compares with a {smalltilde} 50-fold increase for the 5-HTOL/5-HIAA ratio in the firstmorning void. Both methanol and the 5-HTOL/5-HIAA ratio remainedelevated above pre-drinking baseline values in the second andsometimes even the third morning voids. Most subjects experiencedonly mild hangover symptoms after drinking 50 g ethanol (meanscore 2.4 ± 2.6), but the scores were significantly higherafter drinking 80g (78 ± 7.1). The most common symptomswere headache, drowsiness, and fatigue A highly significantcorrelation (r = 0.62–0.75, P <0.01) was found betweenthe presence of headache, nausea, and vertigo and the urinarymethanol concentration in the first and second morning voids,whereas 5-HTOL/5-HIAA correlated with headache and nausea. Theseresults show that analysing urinary methanol and 5-HTOL furnishesa way to disclose recent drinking after alcohol has no longerbeen measurable by conventional breath-alcohol tests for atleast 5–10 h. The results also support the notion thatmethanol may be an important factor in the aetiology of hangover.     

ALTERATION OF ACETALDEHYDE METABOLISM IN CARBON TETRACHLORIDE-INTOXICATED RAT LIVER: ANALYSIS USING LIVER PERFUSION SYSTEM

The hepatic metabolism of acetaldehyde in carbon tetrachloride(CCl₄)-intoxicated rats was studied using a non-recirculatinghaemoglobin-free liver-perfusion system. Acetaldehyde uptakeby the liver from acutely CCl₄-treated animals (4.16 mmol/kg,i.p.) at 24 hr after the treatment was not significantly altered,whereas that by the liver from chronically CCl₄-treated animals(2.08 mmol/kg,i.p., twice a week, for 8–12 weeks) wasdecreased by approximately 50% when it was determined in thepresence of 0.01–5 mM acetaldehyde. In liver from ratschronically intoxicated with CCl₄, the following important biochemicalchanges were observed: (1) The activity of low K_m aldehyde dehydrogenase(ALDH) in hepatic mitochondria was decreased by approximately75%. (2) The basal levels of the lactate/pyruvate (cytosolic[NADH]/[NAD⁺]) ratio as well as the ß-hydroxybutyrate/acetoacetate(mitochondrial [NADH]/[NAD⁺]) ratio were elevated by more than2-fold. (3) Mitochondrial NADH oxidation was also reduced byapproximately 35% of the control level. (4) The basal levelof hepatic oxygen uptake was attenuated by approximately 50%,and the infusion of acetaldehyde (0.01–5.0 mM) causeda further decrease in the uptake. (5) The rate of ethanol productionfrom acetaldehyde by the catalytic action of alcohol dehydrogenasewas found to be unaltered when low concentrations of acetaldehyde(0.01–0.2 mM) were used, whereas a significant suppressionof the rate of ethanol production was detected in the presenceof high concentrations of acetaldehyde (0.6–5 mM). Thesedata suggest that the changes in activity of the lowK_m mitochondrialacetaldehyde dehydrogenase and those in mitochondrial NADH oxidationcoupled with mitochondrial respiration may, at least in part,play important roles in the decreased hepatic acetaldehyde metabolismobserved in chronically CCl₄-treated rats.     

DETERMINATIONS OF ETHANOL, ACETALDEHYDE AND ACETATE IN BLOOD AND URINE DURING ALCOHOL OXIDATION IN MAN

Blood and urine samples were analyzed for ethanol, acetaldehydeand acetate during alcohol oxidation in Japanese men by headspace gas chromatography, following the consumption of 16 ml/kgof beer during a 20 min period. The maximum level of blood/urineethanol was found to be 15–17 mM (20–22 mM), whilethat of acetaldehyde in a flusher and in non-flushers was 20µM (52 µM) and 2–5 µM (10–13 µM),respectively. Acetate levels in these groups ranged from 0.2mM (0.1 mM) to 0.8 mM (1.0 mM). Blood ethanol levels were dosedependent, whereas acetaldehyde and acetate levels reflectedindividual metabolic rates. The relative concentrations of ethanoland acetaldehyde in blood and that of acetate in alcohol metabolismcould be summarized as follows: 7500 (15 mM): 1–3 (2–5µM); 250–400 (0.5–0.8 mM) for non-flushers;and 7500 (15 mM): 5–10 (10–20 µM): 250–400(0.5–0.8 mM) for a flusher.     

AN NMR STUDY OF CEREBRAL OEDEMA AND ITS BIOLOGICAL CORRELATES DURING WITHDRAWAL FROM ALCOHOL

Five chronic alcoholic patients admitted for detoxificationwere studied. During the first 24–48 hr of abstinenceraised levels of cerebral water (as measured by NMR), vasopressin,renin and supine aldosterone were recorded. Initial vasopressinconcentration was correlated (r=0.88, P<0.05) with alcoholconsumption in the week prior to admission and was over threetimes higher in the patients measured after 24–48 hr ascompared to less than 24 hr. After one week only supine aldosteronewas still raised (P<0.05). The results suggest that cerebraloedema occurs during the early stages of abstinence. The roleof these changes in the aetiology of withdrawal symptoms, deliriumtremens and brain damage remains to be elucidated.     

INVOLVEMENT OF GENETIC POLYMORPHISM OF ALCOHOL AND ALDEHYDE DEHYDROGENASES IN INDIVIDUAL VARIATION OF ALCOHOL METABOLISM

The involvement of genetic polymorphism at the alcohol dehydrogenase2 (ADH2) and aldehyde dehydrogenase 2 (ALDH2) loci in determiningblood acetaldehyde levels and the rate of ethanol eliminationafter ethanol intake was investigated. Sixty-eight healthy subjectsingested 0.4 g of ethanol per kg of body weight over 10 min.Blood acetaldehyde levels scarcely increased in the subjectshomozygous for ALDH2^*I, regardless of their ADH2 genotypes (ADH2^*1/^*1,ADH2^*1/^*2 and ADH2^*2/^*2). The acetaldehyde levels in the subjectswith the ALDH2^*1/^*2 heterozygote increased to 23.4 µMon average, and no significant differences were observed betweenthe three ADH2 genotype groups. Subjects homozygous for ALDH2^*2showed very high levels of blood acetaldehyde, and the averagevalue was 79.3 µM. The values of Widmark's ß₆₀(mg/ml/hr)and ethanol elimination rate (mg/kg/br) showed significant differencesamong the three ALDH2 genotypes, and in decreasing order thevalues were ALDH2^*1/^*1, ALDH2^*1/^*2, ALDH2^*2 However, no significantdifferences were seen among the ADH2 genotypes.     

Elevated blood acetate as indicator of fast ethanol elimination in chronic alcoholics

The concentration of acetate was determined in the hepatic and peripheral blood of 10 chronic alcoholics and six healthy non-alcoholic controls after a peroral dose of ethanol (0.8 g/kg b.wt.). The blood acetate concentration was significantly higher in the hepatic vein than peripherally and remained at a rather constant level both in alcoholics and controls during the course of ethanol elimination. However, the level of acetate was significantly (p less than 0.005) higher in alcoholics than in controls both in the hepatic vein (1.79 and 1.15 mM) and peripherally (0.91 and 0.52 mM) (alcoholics and controls respectively). The alcoholics also eliminated ethanol 54% faster than the controls (159 mg/kg b.wt./hr and 103 mg/kg b.wt./hr; alcoholics and controls respectively). Furthermore a highly significant correlation was found between the rate of ethanol elimination and blood acetate level both in the hepatic (r = 0.877, p less than 0.001) and in the peripheral vein (r = 0.799, p less than 0.001). Our results suggest that an increased level of blood acetate during ethanol oxidation may be used as an indicator of enhanced ethanol elimination.     

ETHANOL-INDUCIBLE CYTOCHROME P-450 ACTIVITY AND INCREASE IN ACETALDEHYDE BOUND TO MICROSOMES AFTER CHRONIC ADMINISTRATION OF ACETALDEHYDE OR ETHANOL

Chronic ethanol consumption results in acetaldehyde adduct formationwith proteins such as haemoglobin and liver proteins in vivo.Our purpose was to study the binding of acetaldehyde to livermicrosomal proteins, a site of ethanol oxidation via cytochromeP-450 (especially P-450 II E1), after chronic administrationof ethanol or acetaldehyde for 21 days to rats. The liver microsomaloxidation of 1-butanol by the ethanol-inducible P-450 also wasexamined. Acetaldehyde bound to liver microsomal proteins washigher in ethanol-fed rats compared with acetaldehyde-treatedrats (0.735 vs 0.413 nmol/mg of protein respectively). The biotransformationof n-butanol to butyraldehyde by liver microsomes was increased(by 136%) in ethanol-fed rats vs controls, whereas in acetaldehyde-treatedrats this increase was much lower (only 27%). However, in thislast group, a significant negative relationship between thequantity of acetaldehyde bound to microsomal proteins and themonooxygenase-catalyzed transformation of butanol by liver microsomeswas demonstrated (r = –0.79, P < 0.01). These resultssuggest that proteins of liver microsomes are a target for acetaldehydebinding during ethanol oxidation and such adduct formation couldimpair the oxidative properties of the alcohol-inducible cytochromeP-450.     

EFFECT OF CHRONIC ETHANOL CONSUMPTION ON IN VIVO PROTEIN SYNTHESIS IN LIVERS FROM FEMALE AND MALE RATS FED TWO DIFFERENT DIET REGIMENS

Hepatic protein synthesis was studied in male and female ratsfed ethanol-supplemented diets for 6–7 weeks. In one group(group 1), male rats were fed an all-liquid diet with 36% ofthe energy as ethanol. The controls were pair-fed with carbohydratereplacing ethanol isoenergetically. The second group of malerats (group 2) was given a mixture of solid and liquid diets.The solid food was given ad libitum and was supplemented witheither an ethanol-containing liquid (20–30% of energyas ethanol) or isoenergetic amounts of lipid. Female rats (group3) received the same diet regimen as group 2. Rates of hepaticprotein synthesis were measured after a 12–18 hr fastby a 32 min continuous infusion of ³H-valine. Specific precursorradioactivity (valyl tRNA) was calculated from valine specificradioactivities and concentrations in intra- and extracellularwater at 12, 22 and 32 min. The rates of protein synthesis were lower in all three groupsof ethanol-treated rats than in controls. In group 1, ethanolfeeding resulted in protein accumulation, and the plasma proteinconcentration was significantly lower at 20 and 32 min. In conclusion,female and male rats fed various diets were susceptible to thesame inhibitory effect of chronic ethanol consumption on hepaticprotein synthesis.     

ETHANOL AND PHOSPHATIDYLETHANOL REDUCE THE BINDING OF [3H]INOSITOL 1,4,5-TRISPHOSPHATE TO RAT CEREBELLAR MEMBRANES

In this study, we have analysed the effect of ethanol and phosphatidylethanol,a unique phospholipid formed only in the presence of ethanol,on the binding of [³H]inositol 1,4,5-trisphosphate to rat cerebellarmembranes. Rats were intraperitoneally injected daily with 3g of ethanol/kg body weight for different periods of time. Repeatedadministration of ethanol induced a reduction in the bindingcapacity (B_max) without affecting the affinity constant (K_d).A significant 32% reduction was observed after 21 days of exposure(from control B_max values of 25±3 pmol/mg and K_d valuesof 9±2 nM). In an in-vitro assay, phosphatidylethanol(500 µM) and phosphatidic acid (500 µM), but noother phospholipids tested, induced a reduction in B_max (39%and 43%, respectively). The observed effect displayed by phosphatidylethanolwas not due to its degradation to phosphatidic acid or otherphospholipids. The results emphasize the importance of examiningphosphatidylethanol (PEth) as a possible mediator of the effectsof ethanol on cellular processes. However, the role of PEthin the observed effect of long-term ethanol exposure still needsfurther consideration.     

RATES OF METABOLISM OF ETHANOL TO ACETATE BY HUMAN NEUTROPHIL PRECURSORS AND MACROPHAGES

Studies employing uninduced and dimethylsulphoxide-induced HL60)cells have shown that (1) promyelocytes metabolise ethanol (0.1mg/ml) to acetate at the rate of 3.9 nmol/10⁷ cell/hr and (2)there is a progressive fall in the ethanol-metabolislng capacityas promyelocytes mature into neutrophil myelocytes and, eventually,to band forms and neutrophil granulocytes. By contrast, macrophagesderived from the treatment of HL60 cells with 1,25 [OH]₂ vitaminD₃ and from the culture of normal blood monocytes metabolisedethanol to acetate at much higher average rates of 180.1 and184.7 nmol/10⁷ cell/hr. Furthermore. nucleated marrow cell suspensionswhich were depleted of cells capable of adhering to plasticmetabolised ethanol at only one-third the rate shown by non-depletedcell suspensions. The data indicate that neutrophils and theirgranule-contaming precursors contribute relatwely little andmacrophages contribute substantially to the overall rate ofethanol metabolism by suspensions of nucleated marrow cells.In addition, the considerable capacity of macrophages to mctaboliscethanol in vitro raises the possibility that the metabolismof ethanol by thew cells in vivo may result in some deleteriouseffect on surrounding cells and thus. account, at least in part.for ethanol-induced tissue damagealcoholic subjects is reported.Further studies are needed to confirm this latter finding andto assess fully its possible significance.     

Interindividual variations in the disposition and metabolism of ethanol in healthy men

Forty-eight healthy men each drank a dose of ethanol, 0.68 g/kg of body weight, as neat whisky at about 09.00, after fasting overnight. The drink was finished within 20 min and the concentrations of ethanol in samples of capillary blood were determined at 30–60 min intervals for 7 hr. Rectilinear regression lines were fitted to the elimination phase of blood concentration time profiles and blood-ethanol parameters were calculated as described by Widmark. In 23, 14, 8 and 3 subjects the peak blood ethanol concentrations were reached at 30, 60, 90 and 120 min timed from starting to drink. The highest concentration of ethanol in blood was 0.92±0.022 mg/ml (mean ±SE) and the coefficient of variation (CV) was 16.8%. The blood concentration of ethanol extrapolated to zero-time was 0.98±0.009 mg/ml (CV=6.5%) and the apparent volume of distribution (V_d) was 0.695±0.0064 L/kg (CV=6.4%). The rate of ethanol elimination from blood was 0.126±0.0018 mg/ml/hr (CV=9.9%) and the body clearance was 87.5±1.1 mg/kg/hr (CV=8.7%). The apparent volume of distribution of ethanol was inversely related to the subject's body weight (r=?0.59±0.118, p<0.001). The elimination rate from blood was lower in those subjects with larger distribution volume; the parameters were negatively correlated (r=?0.52±0.126, p<0.001). The results show that blood-ethanol parameters calculated according to Widmark's method have low intersubject variability when the dose of ethanol administered and the condition of the test subjects are carefully controlled. A more sophisticated mathematical treatment of ethanol pharmacokinetics may be unnecessary.     

DIFFERENTIAL EFFECT OF CHRONIC ALCOHOL INTAKE AND POOR NUTRITION ON BODY WEIGHT AND FAT STORES

A six-months out-patient study of chronic alcoholics with undecompensatedliver disease has shown a statistically significant inversecorrelation between the change in mean corpuscular volume andthe change in body weight (r = –0.4, P < 0.01). A fallin body weight over this period was the best clinical indicatorof apparently continuing alcohol abuse. Previous anthropometricstudies have indicated that reduced adipose tissue is one causeof lower body weights in such patients. To determine whetherthis is due to the effects of alcohol or of poor nutrition,the epididymal fat pad weights of rats following 28 days administrationof alcohol (36% of total calories) as part of a nutritionallyadequate liquid diet were compared with those of pair-fed controlsinitially matched for body weight. At the end of the experiment,body weight gain was the same in both groups but the mean weightof the fat pads of alcohol-fed animals (371.7 mg ± 60.0mg SD) all of which developed hepatic steatosis was 29% greaterthan that of pair-fed controls (288.7 mg ± 42.4 mg).This difference was statistically significant (P < 0.025).This study shows that alcohol intake per se does not preventan increase in body weight or fat even if hepatic steatosisis induced and that loss of adipose tissue in chronic alcoholicswho continue to drink is probably due to simultaneous inadequatenutritional intake.     

EFFECT OF ACUTE AND CHRONIC ETHANOL ADMINISTRATION ON THE TRANSPORT OF THIAMINE FROM PLASMA TO DIFFERENT BRAIN REGIONS OF THE RAT

The effect of ethanol (4.7 g/kg body wt intragastrically asa single dose or once daily for 35 days) on the transport ofthiamine from plasma to four brain regions (cerebellum, cerebralcortex, pons and medulla) was studied in albino rats. Animalswere given an intravenous injection of labelled thiamine witha sampling procedure which allowed the determination of regionalblood flow and tissue thiamine uptake. Regional blood flow wasfound to be enhanced after acute, but non chronic, ethanol administration.The magnitude of increase ranged from 13 to 35% depending onthe brain region being considered. Thiamine was transferredfrom plasma to cerebral tissue by a saturable process with anon-saturable component prevailing at thiamine concentrationsabove 10–15 µM. Three main modifications in thethiamine transport were found as a result of ethanol treatment:a reduction in affinity for the carrier (K_m increased), an increasein maximal transport rate (J_max and an increase in non-saturablediffusion (K_D constant increased). The effects were more pronouncedafter acute ethanol administration. As a consequence of thesemodifications both acute and chronic ethanol treatment causedan increase in thiamine transport rate at high plasma concentrations.On the contrary, at low (physiological) plasma concentrations,thiamine transport was little increased by acute ethanol administrationand virtually unaffected by chronic ethanol intoxication.     

CHARACTERIZATION OF RAT TESTICULAR ALCOHOL DEHYDROGENASE

A protein from rat testes that catalyzes the oxidation of ethanolin the presence of NAD⁺, but not NADP⁺, has been characterizedenzymatically and compared to that of hepatic alcohol dehydrogenaseobtained from the same animals. The testicular enzyme, likethe hepatic enzyme, has a K_m value for ethanol in the 0.5–1.0-mMrange and can utilize other alcohols such as n-propanol, n-butanol,and isobutanol, although the K_m values for these other alcoholsare considerably lower (0.03–0.08 mM) that that for ethanol.The testicular enzyme is more heat-labile than is the hepaticenzyme. Finally, the testicular enzyme catalyzes the oxidationof retinol and its retinol dehydrogenase activity is inhibitedby ethanol.     

EXCRETION OF MALONDIALDEHYDE, FORMALDEHYDE, ACETALDEHYDE AND ACETONE IN THE URINE OF RATS FOLLOWING ACUTE AND CHRONIC ADMINISTRATION OF ETHANOL

Recent studies have shown that xenobiotics which induce oxidativeStress result in an increased production and excretion of acetaldehyde(ACT), formaldehyde (FA), acetone (ACON) and malondialdehyde(MDA) in the urine of rats. We have therefore examined the effectof acute and chronic ethanol administration on the excretionof these four lipid metabolites in female Sprague-Dawley rats.Urine samples were collected over dry ice for 6 hr time periods.Aliquots of urine were derivatized with 2,4-dinitrophenylhydrazineHCl, and extracted with n-pentane. High pressure liquid chromatography(HPLC) was used to quantitate and the hydrazones of the fourlipid metabolite products. Following a single, oral, acute doseof 5 g ethanol/kg, urinary excretion of ACT increased approximately5.8-fold from 6 to 12 hr post-treatment, and decreased thereafter.FA excretion decreased by approximately 50% from 0 to 12 hr,returned to control values in the 18–24 hr urine samples,and was 1.3-fold greater than control values at 42–48hr. ACON increased 3.1-fold over control values from 0 to 30hr and remained elevated throughout the remaining 18 hr of thestudy. The excretion of MDA increased approximately 1.5-foldfrom 18 to 36 hr, then remained constant through the 48 hr timepoint. In a separate series of experiments, a chronic oral doseof 0.5 g ethanol/kg was administered to rats for 10 consecutivedays and the urinary excretion of the lipid metabolites MDA,FA, ACT and ACON was examined for 11 days, beginning with thefirst day of ethanol administration. During the chronic administrationof ethanol, a significant increase in the urinary excretionof ACT began on day 4. An increase in ACON excretion was firstobserved on day 6, and increases in MDA and FAexcretion werefirst observed on days 8 and 10, respectively. The results clearlydemonstrate that both acute and chronic alcohol consumptionmarkedly afier lipid metabolism and the excretion of lipid metabolites.     

STIMULATION OF CHEMICALLY INDUCED RECTAL CARCINOGENESIS BY CHRONIC ETHANOL INGESTION

The effect of chronic ethanol administration on 1. 2-dimethylhydrazine-inducedrectal carcinogenesis was investigated in 32 paired male Sprague-Dawleyrats fed a nutritionally-adequate liquid diet containing 36%of the total calories as either ethanol or isocaloric carbohydrates.Chronic ethanol ingestion increased the total number of rectaltumors significantly (17 vs 6; P<0.02), whereas no cocarcinogeniceffect of ethanol was observed in other parts of the intestine.Alcohol did not influence tumor size or histopathology. A 47%increase in the activity of mucosal alcohol dehydrogenase inthe distal colorectal region was found between chronically-ethanol-fedrats and pair-fed controls (0.241± 0.019 vs 0.164±0 020 µmol/mg of protein/hr; P<0.01). This could inpart explain the cocarcinogenic effect of alcohol in this tissue.Faecal bile acids, however, do not play a role as promotorsof rectal carcinogenesis under the present experimental conditions.The results give experimental support to the epidemiologic findingsof an increased incidence of rectal cancer in the alcoholic.     

CHRONIC ETHANOL EXPOSURE INCREASES LIPOPIGMENT ACCUMULATION IN HUMAN HEART

The amount and distribution of myocardial lipoptgments ( ‘agepigments’) were studied in alcoholic and control humanhearts, to test the hypothesis of ethanol-induced long- termoxidative damage in myocardium. The amount of myocardial lipopigmentswas measured by image analysis in six men (age 34–60 years)who had a history of chronic alcohol misuse and who died ofacute ethanol intoxication, and in their age-matched, non-alcoholiccontrols. Lipopigmentation in the intoxication cases was 33.5± 2.8% (mean ± SEM) higher compared to the controlsin the eight myocardial areas studied (P < 0.001). A linearcorrelation of myocardial lipopigmentation with age was noticedin both the intoxication group (R = 0.894) and the controls(R = 0.927). The amount of lipopigments varied largely fromone myocardial area to another, being highest in the most strainedareas (left ventricle, interventricular septum). The accumulationof lipopigments is considered a marker of oxidative stress andageing in the myocardium. The results support the role of freeradical-induced oxidative stress in the pathogenesis of ethanol-inducedcardiac abnormalities.