- Email: [email protected]
Ethanol-induced changes in the oxidative metabolism of arachidonic acid
Prostaglandins Leukotrienes and Medicine 9:
151-157, 1982
ETHANOL-INDUCED CHANGESIN THE OXIDATIVE METABOLISM OF ARACHIDONIC ACID Sam N. Pennington, David G. Woody, and Roy A. Rumbley Department of Biochemistry School of Medicine East Carolina University Greenville, North Carolina 27834 (reprint requests to SNP)
ABSTRACT Previous reports have suggested that ethanol (ETOH) consumption alters the metabolism of polyunsaturated fatty acids. In several models, acute ETOH exposure has been shown to stimulate the synthesis of PGEl tion depletes from diholnogansaa-linolenic acid, while chronic ETOH cons microsomal arachidonate levels and presumably lowers the availability of substrate for the synthesis of PGs and related compounds of the "2" series. Chronic ETOH has also been reported to inhibit lfi-hydroxyprostaglandin dehydrogenase (PGDH) activity, the enzyme responsible for degrading the PGs. In the experiments reported here, we have measured microsomal levels of arachidonic acid, prostacyclin (PGI,) synthetase activity, and the kinetic parameter of PGDH in male rats chronically dosed with varying amounts of ETOH. In animals matched for nutritional intake, ETOH caused a dose dependent lowering of the microsomal arachidonate content of heart, brain, and liver. Kidney micrownal arachidmate levels were significantly increased by ETOH. Total and specific PGDH activity in these kidneys were lowered by chronic exposure to ETOH. PGDH activity fell to 80% and 62% of control values at three and six weeks, respectively. In addition the catalytic efficiency of the remaining PGDH activity was significantly lowered. PGI synthesis in the stomachs and aortas of the ethanol-treated animals showed
151
a biphasic dose response, i.e., moderate ETOH exposure stimulated PGI, synthesis in both aortas and stomach fundi while high ETOH levels lowered the activity. This biphasic dose response of PG12 synthetase mimics certain aspects of the cardiovascular response to ETOH. INTRODUCTION Despite significant research, the molecular mechanisms responsible for the diverse pathophysiology of chronic alcoholism are poorly understood. Medical intervention to prevent the damage associated with ethanol consumption depends, in large part, on persuading the individual to abstain or to moderate his alcohol consumption. Nevertheless, the majority of problem drinkers fail to comply with this therapeutic approach and as a result develop a variety of medical problems. The diverse pathology resulting from alcohol abuse complicates the study of the molecular response to ethanol. A simple organic compound with unique solubility properties which induces a variety of pathophysiologic responses is intriguing. The wide range of tolerated dosages certainly plays an important role in the physiological response to ETOH, but it is difficult to understand how such a simple compound can alter so many systems. Recent evidence suggests that ethanol-induced alterations in the owidative metabolism of arachidonic acid and related prostaglandin like compounds may represent part of the molecular mechanism responsible for ethanol's effect (1). Ethanol and the prostaglandins (PG) show broad spectrums of physiological activity. For example, both are active in the cardiovascular (2), gastrointestinal (3), reproductive (4), and central nervous systems (5). It might be hypothesized therefore that ethanol-induced alterations in the metabolism of the prostaglandins represent part of the molecular mechanism by which chronic alcohol consumption alters these systems. Ongoing research has suggested three mechanisms by which ethanol may influence PG metabolism. It has been reported that chronic ethanol consump. tion lowers microsomal levels of arachidonic acid, the substrate for PGEP, PGF2, prostacyclin (PGI,), and thromboxane (TXA,) synthesis, while acute ethanol exposure stimulates synthesis of PGE, [for a review and possible clinical implications see reference (l)]. In addition, chronic ethanol exposure has been shown to inhibit 15-hydroxyprostaglandin dehydrogenase (PGDH) the enzyme responsible for degrading the biological potency of the PGs (7). The study described here was carried out to further examine the interaction between ETOH and arachidonic acid metabolism. A liquid diet was pair-fed to 3 groups of male Holtzman rats with each group receiving either 0, 17% or 35% of their calories as ethanol. The diets were fed to each group for 6 weeks and the animals then sacrificed.
152
Tissue levels of arachidonic acid in the nticrosml fraction of brain, heart, liver, lung, and kidney were determimd. PGIZ synthesis by homogenates of stomach fundi and aortas from these animals was also measured. Finally, the effects of ETOH on kidney PGDH specific activity and kinetic parameters were determined. METHODS AND MATERIALS Animals and Ethanol Dosing Twenty-four male Holtzman rats (approximately 200 grams at the start of dosing) were divided into three groups and one animal from each group was weight-paired to an animal in the other two groups to give eight groups of three weight-matched animals each. One animal in each of the 8 roups was allowed to consume a free choice amount of a liquid diet (6s containing 35% of the calories as ethanol and its weight-matched partners were given an equal volume of isocaloric liquid diet containing 17% or 0% calories as ethanol, respectively. The animals were maintained on a 12 hours on, 12 hours off light cycle with the diet being replaced daily prior to the animals entering the dark portion of the cycle. Blood alcohol levels were determined two hours after access to the diet. The animals were anesthetized using chloral hydrate (60 t&g/kg) to slow the metabolism of ETOH during withdrawal of the blood samples by heart puncture. Blood ETOH levels were determined by a gas chromatographic method previously described (7). Tissue Isolation and Preparation Following consumption of the diets for 6 weeks, the animals were sacrificed by decapitation. Heart, liver, lungs, kidneys, aorta, and stomach fundus were rapidly excised and placed in ice cold KC1 (1.15%). The microsomal fractions from brain, liver, lungs, and one kidney (left) were prepared by differential centrifugation following homogenization of the tissue in cold phosphate buffer, 0.1 M, pH 7.4. Stomach fundi and aortas were individually homogenized (1.0 g/25 ml) in Tris-HCl buffer 0.1 M, pH 7.8 containing 0.001 M EDTA. The right kidney from each animal was homogenized (1.0 g/20 ml) in phosphate buffer, 0.05 M, pH 7.4 using a glass-Teflon homogenizer. The homogenate was strained through four layers of cheese cloth, spun at 600 x g, 15,000 x g, and 100,000 x g and the supernatant was used immediately for the PGDH assay (see below). Determination of Microsomal Arachidonate Microsomal pellets were resuspended in phosphate buffer (1 mg protein/ml) and 0.5 ml of the suspension extracted by the method of
153
Folch (8). The Folch extracts were blown to dryness under N2 and 40 micrograms of C fatty acid added as an external standard. Fatty acid methyl estQ::'!&AMEs) were prepared by the method of Matcalfe et al. (9). Following formation of FAMES, the samples were blown to dryzss (N2) and redissolved in 50 microliters of CS2. FAMES mixtures were separated on a Perkin Elmer model Sigma II gas chromatograph equipped with dual flame ionization detectors using 10% EGGS-X columns (6 ft.) operated at 195°C. Detector output was fed to a Varian model CDS-111 calculating integrator for quantitation. All microsome samples were run in duplicate. &
Synthesis Assay
Stomach fundus and aorta homogenates in Tris-HCl (1 g/ml) were bubbled with 0, for 1 minute followed by the addition of 1-"C labeled arachidonate (1 uCi) and vortexing. The capped sample tubes were incubation 10 minutes at 37°C in a shaking water bath. After 0 and 10 minutes of incubation, 25 microliter samples were spotted directly on Whatman LK6D preabsorbant TLC plates and developed twice in ethyl acetate, H20, isooctane and acetic acid (55:50:25:10, upper phase). Spots were identified by comparison to authenic standards spotted on the same plate and visualized by spraying with p-anisaldehyde-H*SO+ reagent. Radioactive spots were located by scanning the plate with a Berthold TLC scanner. Radioactive spots were scrapped from the TLC plates and quantitated by liquid scintillation counting. PGDH Determinations The analytical and kinetic analyses of this enzyme was by a radiochemical assay using l-14C-PGE, as previously described (7). Protein for all assays was determined by the Lowry method (10). RESULTS AND DISCUSSION Six weeks of liquid diet consumption caused no significant differences in body weights (Table I) or organ weights except that the hearts of the animals receiving 35% ethanol-derived calories weighed significantly less than control (0%) hearts (1.16kO.07 grams versus 0.97+0.06 grams, ~~0.05). Table I.
Experimental Parameters for Three Dietary Ethanol Levels
ETOH Derived Calories 0% (Control) 17% 35%
Animal wt (g)
ETOH (g/kg/day) Blood ETOH (mg/dl)
276.6k4.4 270.6k3.6 273.01t4.8
154
0 10.33kO.31 21.15kO.38
25.:+5 0 109.1+25.9
Ethanol did alter microsomal arachidonate levels in several tissues Relative to the external standard, ethanol caused a significant, dose related lowering of heart microsomal arachidonate content (Table II ). Brain microsomal arachfdonate showed a similar nonsignificant trend. Kidney microsomal arachfdonate content was significantly elevated relative to controls but the increase was not dose related. Table II.
Effect of Dietagy Ethanol Levels on Tissue Arachidonic Acid Content. pqO.05 relative to control diet group. Note: Numbers in parenthesis represent animals per group.
Treatment
Brain
Heart
Liver
Lung
Control diet
0.15+0.04 (6)
0.19+0.00 (6)
2.38kO.16 (6)
O.D3+0.00 (6)
0.15?0.01 (5)
17% diet
0.12+0.02 (5)
0.15+0.01* (6)
2.70i0.11 (6)
O.Ol+O.OO (4)
0.25+0.03* (5)
35% diet
0.11+0.01 (5)
0.12rt0.01" 2.09+0.19 (6) (6)
0.04+0.01 (5)
0.25+0.01* (4)
Kidney
The conversion of exogenous arachidonate to PGI, by aortas and stomach fundi from these animals was altered by ETOH. Consumption of moderate levels of ETOH (17%) significantly stimulated PGI, synthesis (measured as 6-keto PGF, ) while high doses (35%) markedly lowered the activity in both tissue ?Table III). Synthesis of PGI, from exogenous arachidonate by aortas from ETOH-naive rats was not influenced by acute exposure to ETOH during incubation. [Conversion to 6-keto PGFlcrwithout ETOtl= 230 cpm/min/g tissue; with 85 mH ETOH = 212 cpm/min/g tissue, the difference was not significant.] Table III.
Effect of Ethanol Dose on PGI, Synthesis. to control diet group.
Treatment
Stomach (mole/min/mgx1014)
Control diet
5.75kO.98
17% diet
9.35+1.35*
35% diet
4.56+0.41
* p
Chronic ETOH exposure has been reported to lower renal total and specific PGDH activity (7). In a preliminary study, exposure to the high ETOH diet for three weeks resulted in a 20% decrease in renal PGDH specific activity relative to control animals (data not shown). At the
155
end of 6 weeks, PGDH specific activity in the high ETOH group had fallen to 62% of control values. Moreover, in the presence of greater than 10 times the Km concentration of NAD and using PGE2 as the substrate, changes in the catalytic efficiency of the remaining PGDH activity wereobserved. Consumption of the high ethanol diet for 6 weeks resulted in a decrease in both the K,(app) and Vmax of the enzyme (Table IV). The moderate ETOH diet raised the Km(app) but had no effect on vmax. Table IV.
Effect of Ethanol Dose on the Kinetic Parameters of Renal PGDH
Treatment
Km (app) (I1M)
h
(nm/min)
Control diet
6.03
0.11
17% diet
9.49
0.13
35% diet
1.66
0.06
The physiological significance of these observations is difficult to determine because the -in vivo levels of PGE, are well below these values. Further, the in viva concentration of both PGE, and NAD may be altered by the chroxczsumption of ethanol. The biphasic dose response of PGlYiand PGI, synthetase relative to ethanol dose does mimic the biphasic dose response of several of the parameters of the cardiovascular system to ethanol. REFERENCES 1.
Horrobin DF. A biochemical basis for alcoholism and alcohol-induced damage including the fetal alcohol syndrome and cirrhosis; Interference with essential fatty acid and prostaglandin metabolism. Medical Hypothesis 6: 929, 1980.
2.
Edgarian H, Altura BM. Differential effects of ethanol on prostaglandin response of arterial and venous smooth muscle. Experientia 32: 618, 1976.
3.
Karppanen H and Puurunen J. Ethanol, indomethacin, and gastric acid secretion in the rat. Eur. J. Pharmacol. 35: 221, 1976.
4.
Karim SW4 and Sharma SD. The effect of ethyl alcohol on PGE2 and F,, induced uterine activity in pregnant women. J. Obstet. Gynec. 78: 251, 1971.
5.
George RF and Collins AC. Prostaglandin synthesis inhibitors antago. nize the depressant effects of ethanol. Phamulcol. Biochem. Behav. 10: 865, 1979.
156
6.
Riley EP, Lochey EA, Shapiro NR, and Baldwin J. Response preservation in rats exposed to alcohol prenatally. Pharmacol. Biochem. Behav. 10: 255, 1979.
7.
Pennington SN, Rumbley RA, and woody DG. Fetal 15-hydroxyprostaglan din dehydrogenase is altered by maternal ethanol exposure. Biol. Neonate 40: 246, 1981.
8.
Folch J, Lees M, and Sloane-Stanley GH. A simple method for the isolation and purification of total lipids from animal tissues. J. Biol. Chem. 226: 497, 1957.
9.
Metcalfe LD, Schmitz AA, and Pekala JR. Rapid preparation of fatty acid esters from lipids for gas chromatographic analysis. Anal. Chem. 38: 514, 1966.
10.
Lowry OH, Rosebrough NJ, Farr AL, and Randall RJ. Protein measurement with Folin phenol reagent. J. Biol. Chem. 193: 265, 1951.
157
151-157, 1982
ETHANOL-INDUCED CHANGESIN THE OXIDATIVE METABOLISM OF ARACHIDONIC ACID Sam N. Pennington, David G. Woody, and Roy A. Rumbley Department of Biochemistry School of Medicine East Carolina University Greenville, North Carolina 27834 (reprint requests to SNP)
ABSTRACT Previous reports have suggested that ethanol (ETOH) consumption alters the metabolism of polyunsaturated fatty acids. In several models, acute ETOH exposure has been shown to stimulate the synthesis of PGEl tion depletes from diholnogansaa-linolenic acid, while chronic ETOH cons microsomal arachidonate levels and presumably lowers the availability of substrate for the synthesis of PGs and related compounds of the "2" series. Chronic ETOH has also been reported to inhibit lfi-hydroxyprostaglandin dehydrogenase (PGDH) activity, the enzyme responsible for degrading the PGs. In the experiments reported here, we have measured microsomal levels of arachidonic acid, prostacyclin (PGI,) synthetase activity, and the kinetic parameter of PGDH in male rats chronically dosed with varying amounts of ETOH. In animals matched for nutritional intake, ETOH caused a dose dependent lowering of the microsomal arachidonate content of heart, brain, and liver. Kidney micrownal arachidmate levels were significantly increased by ETOH. Total and specific PGDH activity in these kidneys were lowered by chronic exposure to ETOH. PGDH activity fell to 80% and 62% of control values at three and six weeks, respectively. In addition the catalytic efficiency of the remaining PGDH activity was significantly lowered. PGI synthesis in the stomachs and aortas of the ethanol-treated animals showed
151
a biphasic dose response, i.e., moderate ETOH exposure stimulated PGI, synthesis in both aortas and stomach fundi while high ETOH levels lowered the activity. This biphasic dose response of PG12 synthetase mimics certain aspects of the cardiovascular response to ETOH. INTRODUCTION Despite significant research, the molecular mechanisms responsible for the diverse pathophysiology of chronic alcoholism are poorly understood. Medical intervention to prevent the damage associated with ethanol consumption depends, in large part, on persuading the individual to abstain or to moderate his alcohol consumption. Nevertheless, the majority of problem drinkers fail to comply with this therapeutic approach and as a result develop a variety of medical problems. The diverse pathology resulting from alcohol abuse complicates the study of the molecular response to ethanol. A simple organic compound with unique solubility properties which induces a variety of pathophysiologic responses is intriguing. The wide range of tolerated dosages certainly plays an important role in the physiological response to ETOH, but it is difficult to understand how such a simple compound can alter so many systems. Recent evidence suggests that ethanol-induced alterations in the owidative metabolism of arachidonic acid and related prostaglandin like compounds may represent part of the molecular mechanism responsible for ethanol's effect (1). Ethanol and the prostaglandins (PG) show broad spectrums of physiological activity. For example, both are active in the cardiovascular (2), gastrointestinal (3), reproductive (4), and central nervous systems (5). It might be hypothesized therefore that ethanol-induced alterations in the metabolism of the prostaglandins represent part of the molecular mechanism by which chronic alcohol consumption alters these systems. Ongoing research has suggested three mechanisms by which ethanol may influence PG metabolism. It has been reported that chronic ethanol consump. tion lowers microsomal levels of arachidonic acid, the substrate for PGEP, PGF2, prostacyclin (PGI,), and thromboxane (TXA,) synthesis, while acute ethanol exposure stimulates synthesis of PGE, [for a review and possible clinical implications see reference (l)]. In addition, chronic ethanol exposure has been shown to inhibit 15-hydroxyprostaglandin dehydrogenase (PGDH) the enzyme responsible for degrading the biological potency of the PGs (7). The study described here was carried out to further examine the interaction between ETOH and arachidonic acid metabolism. A liquid diet was pair-fed to 3 groups of male Holtzman rats with each group receiving either 0, 17% or 35% of their calories as ethanol. The diets were fed to each group for 6 weeks and the animals then sacrificed.
152
Tissue levels of arachidonic acid in the nticrosml fraction of brain, heart, liver, lung, and kidney were determimd. PGIZ synthesis by homogenates of stomach fundi and aortas from these animals was also measured. Finally, the effects of ETOH on kidney PGDH specific activity and kinetic parameters were determined. METHODS AND MATERIALS Animals and Ethanol Dosing Twenty-four male Holtzman rats (approximately 200 grams at the start of dosing) were divided into three groups and one animal from each group was weight-paired to an animal in the other two groups to give eight groups of three weight-matched animals each. One animal in each of the 8 roups was allowed to consume a free choice amount of a liquid diet (6s containing 35% of the calories as ethanol and its weight-matched partners were given an equal volume of isocaloric liquid diet containing 17% or 0% calories as ethanol, respectively. The animals were maintained on a 12 hours on, 12 hours off light cycle with the diet being replaced daily prior to the animals entering the dark portion of the cycle. Blood alcohol levels were determined two hours after access to the diet. The animals were anesthetized using chloral hydrate (60 t&g/kg) to slow the metabolism of ETOH during withdrawal of the blood samples by heart puncture. Blood ETOH levels were determined by a gas chromatographic method previously described (7). Tissue Isolation and Preparation Following consumption of the diets for 6 weeks, the animals were sacrificed by decapitation. Heart, liver, lungs, kidneys, aorta, and stomach fundus were rapidly excised and placed in ice cold KC1 (1.15%). The microsomal fractions from brain, liver, lungs, and one kidney (left) were prepared by differential centrifugation following homogenization of the tissue in cold phosphate buffer, 0.1 M, pH 7.4. Stomach fundi and aortas were individually homogenized (1.0 g/25 ml) in Tris-HCl buffer 0.1 M, pH 7.8 containing 0.001 M EDTA. The right kidney from each animal was homogenized (1.0 g/20 ml) in phosphate buffer, 0.05 M, pH 7.4 using a glass-Teflon homogenizer. The homogenate was strained through four layers of cheese cloth, spun at 600 x g, 15,000 x g, and 100,000 x g and the supernatant was used immediately for the PGDH assay (see below). Determination of Microsomal Arachidonate Microsomal pellets were resuspended in phosphate buffer (1 mg protein/ml) and 0.5 ml of the suspension extracted by the method of
153
Folch (8). The Folch extracts were blown to dryness under N2 and 40 micrograms of C fatty acid added as an external standard. Fatty acid methyl estQ::'!&AMEs) were prepared by the method of Matcalfe et al. (9). Following formation of FAMES, the samples were blown to dryzss (N2) and redissolved in 50 microliters of CS2. FAMES mixtures were separated on a Perkin Elmer model Sigma II gas chromatograph equipped with dual flame ionization detectors using 10% EGGS-X columns (6 ft.) operated at 195°C. Detector output was fed to a Varian model CDS-111 calculating integrator for quantitation. All microsome samples were run in duplicate. &
Synthesis Assay
Stomach fundus and aorta homogenates in Tris-HCl (1 g/ml) were bubbled with 0, for 1 minute followed by the addition of 1-"C labeled arachidonate (1 uCi) and vortexing. The capped sample tubes were incubation 10 minutes at 37°C in a shaking water bath. After 0 and 10 minutes of incubation, 25 microliter samples were spotted directly on Whatman LK6D preabsorbant TLC plates and developed twice in ethyl acetate, H20, isooctane and acetic acid (55:50:25:10, upper phase). Spots were identified by comparison to authenic standards spotted on the same plate and visualized by spraying with p-anisaldehyde-H*SO+ reagent. Radioactive spots were located by scanning the plate with a Berthold TLC scanner. Radioactive spots were scrapped from the TLC plates and quantitated by liquid scintillation counting. PGDH Determinations The analytical and kinetic analyses of this enzyme was by a radiochemical assay using l-14C-PGE, as previously described (7). Protein for all assays was determined by the Lowry method (10). RESULTS AND DISCUSSION Six weeks of liquid diet consumption caused no significant differences in body weights (Table I) or organ weights except that the hearts of the animals receiving 35% ethanol-derived calories weighed significantly less than control (0%) hearts (1.16kO.07 grams versus 0.97+0.06 grams, ~~0.05). Table I.
Experimental Parameters for Three Dietary Ethanol Levels
ETOH Derived Calories 0% (Control) 17% 35%
Animal wt (g)
ETOH (g/kg/day) Blood ETOH (mg/dl)
276.6k4.4 270.6k3.6 273.01t4.8
154
0 10.33kO.31 21.15kO.38
25.:+5 0 109.1+25.9
Ethanol did alter microsomal arachidonate levels in several tissues Relative to the external standard, ethanol caused a significant, dose related lowering of heart microsomal arachidonate content (Table II ). Brain microsomal arachfdonate showed a similar nonsignificant trend. Kidney microsomal arachfdonate content was significantly elevated relative to controls but the increase was not dose related. Table II.
Effect of Dietagy Ethanol Levels on Tissue Arachidonic Acid Content. pqO.05 relative to control diet group. Note: Numbers in parenthesis represent animals per group.
Treatment
Brain
Heart
Liver
Lung
Control diet
0.15+0.04 (6)
0.19+0.00 (6)
2.38kO.16 (6)
O.D3+0.00 (6)
0.15?0.01 (5)
17% diet
0.12+0.02 (5)
0.15+0.01* (6)
2.70i0.11 (6)
O.Ol+O.OO (4)
0.25+0.03* (5)
35% diet
0.11+0.01 (5)
0.12rt0.01" 2.09+0.19 (6) (6)
0.04+0.01 (5)
0.25+0.01* (4)
Kidney
The conversion of exogenous arachidonate to PGI, by aortas and stomach fundi from these animals was altered by ETOH. Consumption of moderate levels of ETOH (17%) significantly stimulated PGI, synthesis (measured as 6-keto PGF, ) while high doses (35%) markedly lowered the activity in both tissue ?Table III). Synthesis of PGI, from exogenous arachidonate by aortas from ETOH-naive rats was not influenced by acute exposure to ETOH during incubation. [Conversion to 6-keto PGFlcrwithout ETOtl= 230 cpm/min/g tissue; with 85 mH ETOH = 212 cpm/min/g tissue, the difference was not significant.] Table III.
Effect of Ethanol Dose on PGI, Synthesis. to control diet group.
Treatment
Stomach (mole/min/mgx1014)
Control diet
5.75kO.98
17% diet
9.35+1.35*
35% diet
4.56+0.41
* p
Chronic ETOH exposure has been reported to lower renal total and specific PGDH activity (7). In a preliminary study, exposure to the high ETOH diet for three weeks resulted in a 20% decrease in renal PGDH specific activity relative to control animals (data not shown). At the
155
end of 6 weeks, PGDH specific activity in the high ETOH group had fallen to 62% of control values. Moreover, in the presence of greater than 10 times the Km concentration of NAD and using PGE2 as the substrate, changes in the catalytic efficiency of the remaining PGDH activity wereobserved. Consumption of the high ethanol diet for 6 weeks resulted in a decrease in both the K,(app) and Vmax of the enzyme (Table IV). The moderate ETOH diet raised the Km(app) but had no effect on vmax. Table IV.
Effect of Ethanol Dose on the Kinetic Parameters of Renal PGDH
Treatment
Km (app) (I1M)
h
(nm/min)
Control diet
6.03
0.11
17% diet
9.49
0.13
35% diet
1.66
0.06
The physiological significance of these observations is difficult to determine because the -in vivo levels of PGE, are well below these values. Further, the in viva concentration of both PGE, and NAD may be altered by the chroxczsumption of ethanol. The biphasic dose response of PGlYiand PGI, synthetase relative to ethanol dose does mimic the biphasic dose response of several of the parameters of the cardiovascular system to ethanol. REFERENCES 1.
Horrobin DF. A biochemical basis for alcoholism and alcohol-induced damage including the fetal alcohol syndrome and cirrhosis; Interference with essential fatty acid and prostaglandin metabolism. Medical Hypothesis 6: 929, 1980.
2.
Edgarian H, Altura BM. Differential effects of ethanol on prostaglandin response of arterial and venous smooth muscle. Experientia 32: 618, 1976.
3.
Karppanen H and Puurunen J. Ethanol, indomethacin, and gastric acid secretion in the rat. Eur. J. Pharmacol. 35: 221, 1976.
4.
Karim SW4 and Sharma SD. The effect of ethyl alcohol on PGE2 and F,, induced uterine activity in pregnant women. J. Obstet. Gynec. 78: 251, 1971.
5.
George RF and Collins AC. Prostaglandin synthesis inhibitors antago. nize the depressant effects of ethanol. Phamulcol. Biochem. Behav. 10: 865, 1979.
156
6.
Riley EP, Lochey EA, Shapiro NR, and Baldwin J. Response preservation in rats exposed to alcohol prenatally. Pharmacol. Biochem. Behav. 10: 255, 1979.
7.
Pennington SN, Rumbley RA, and woody DG. Fetal 15-hydroxyprostaglan din dehydrogenase is altered by maternal ethanol exposure. Biol. Neonate 40: 246, 1981.
8.
Folch J, Lees M, and Sloane-Stanley GH. A simple method for the isolation and purification of total lipids from animal tissues. J. Biol. Chem. 226: 497, 1957.
9.
Metcalfe LD, Schmitz AA, and Pekala JR. Rapid preparation of fatty acid esters from lipids for gas chromatographic analysis. Anal. Chem. 38: 514, 1966.
10.
Lowry OH, Rosebrough NJ, Farr AL, and Randall RJ. Protein measurement with Folin phenol reagent. J. Biol. Chem. 193: 265, 1951.
157