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Biomedical subjects

Y Israel

Publications and source records attributed to Y Israel.

At least 145 records · Page 8Linked to original sources
PubMed1975

Effects of chronic ethanol treatment and thyroxine administration on ethanol metabolism and liver oxidative capacity.

Chronic administration of ethanol to rats leads to an increase in the rate of ethanol metabolism in vivo and in vitro. In vitro studies in liver slices showed that ouabain, an inhibitor of the Na++K+-activated adenosine triphosphatase, can completely block the extra ethanol metabolism in the livers of the treated animals only in the presence of ouabain. Administration of thyroxine led to an increase in the rate of ethanol metabolism when measured both in vitro and in vivo. This effect was biphasic; an activation occurred only with low doses of thyroxine but disappeared after administration of larger doses. Alcohol dehydrogenase activity in the liver of the animals treated with large doses of thyroxine was found to be significantly reduced. With the doses used (50-1000 mug/kg), thyroxine also increased the rate of oxygen consumption as measured in liver slices. However, a biphasic effect did not occur; a near maximum activation on the rate of oxygen consumption occurred with low doses of thyroxine (100 mug/kg). Oxygen consumption was also found to be increased in the liver of animals chronically treated with ethanol. A maximal effect was produced after 18 to 21 days of treatment. For both ethanol and thyroxine-treated animals, an increased rate of oxygen consumption occurred with a concomitant loss of dinitrophenol effect. Mitochondrial alpha-glycerophosphate oxidase was found to be increased in the liver of animals treated with ethanol or with thyroxine. In these two groups, this enzymatic activity appeared to be less affected by the treatment than the dinitrophenol-activated respiration.

Alcohol Oxidoreductases↗
PubMed1975

Ethanol metabolism and liver oxidative capacity in cold acclimation.

Exposure of rats to an ambient temperature of 5 degrees C for 4 to 6 weeks led to a 30 to 80 percent increase in the rate of oxygen consumption and a 50 percent increase in the rate of ethanol oxidation by liver slices, a 50 percent increase in mitochondrial alpha-glycerophosphate oxidase activity of liver, and a 100 percent increase in Na++K+-activated adenosine-triphosphatase, activity. Ouabain, an inhibitor of the Na++K+-activated adenosine-triphosphatase, completely blocked the extra respiration and ethanol oxidation. Dinitrophenol, which increases oxygen consumption and ethanol oxidation by liver slices from normal rats, was ineffective with slices from cold-exposed animals. Ethanol disappearance rate in vivo was also increased by cold acclimation, even though liver alcohol dehydrogenase activity was reduced. It is suggested that increased hydrolysis of ATP by the sodium pump system is responsible for the increased oxygen consumption and ethanol metabolism in the livers of cold-acclimated animals.

Acclimatization↗
PubMed1975

Hormonal influences in the development of the hypermetabolic state of the liver produced by chronic administration of ethanol.

Chronic administration of ethanol to rats, either in liquid diets as the only source of food or by gastric intubation while the animals are fed ad libitum, leads to the development of a hypermetabolic state of the liver. This hypermetabolic condition of the liver can be observed independently of the feeding state of the animals. The calorigenic effects produced by ethanol in the liver, as measured in liver slices, could be reproduced by a single large dose of epinephrine. Oxygen consumption by liver slices of animals given a 2-mg/kg dose of epinephrine bitartrate increased by 40 to 50 percent. In these livers all the extra oxygen consumption, but not the basal respiration, could be abolished by ouabain, an inhibitor of the sodium pump. Dinitrophenol did not affect the respiratory rate in the liver of epinephrine-treated animals while markedly increasing that in controls. In the liver of treated animals, the activatory effect of dinitrophenol could be recovered in the presence of ouabain. The calorigenic effect of epinephrine in the liver was found to be completely abolished by phentolamine (alpha adrenergic blocker) but was not modified by DL-propranolol (beta adrenergic blocker). Also, the calorigenic effects produced by epinephrine could not be seen in thyroidectomized animals or by incubating the liver slices in a calcium-free medium. Thyroidectomy and administration of phentolamine markedly reduced and adrenalectomy completely abolished the hypermetabolic state produced in the liver of rats by chronic administration of ethanol.

Adrenal Glands↗
PubMed1975

Effects of ethanol on neurotransmitter release by rat brain cortical.

Using a double label technique to preload rat brain cortex slices with different radioactive neurotransmitters (or precursor choline), we have studied the effects of ethanol on the electrically stimulated release of these transmitters. Ethanol inhibited the release of these transmitters, acetylcholine being the most sensitive and occurring at concentrations compatible with moderate to severe intoxication in the rat (IC50 equals 0.17 M). The order of sensitivity to ethanol was acetylcholine greater than serotonin greater than dopamine greater than norepinephrine greater than glutamate greater gamma-aminobutyric acid. Two higher alcohols and two barbiturates were also shown to have a greater inhibitory effect on the stimulated release of acetylcholine than of norepinephrine. The concentrations of all the drugs tested required for 50% inhibition of release of acetylcholine and norepinephrine correlated well with their lipid solubility when corrected for their molecular volumes. The effect of tetrodotoxin and of ouabain on neurotransmitter release was also studied. A comparison of the effects of these two drugs with those of ethanol suggests that the effect of ethanol is consistent with an inhibition of the action potential by this drug, although a specific effect of ethanol on the excitation-coupling process at the synapse cannot by discarded.

Acetylcholine↗
PubMed1973

Metabolic alterations produced in the liver by chronic ethanol administration. Increased oxidative capacity.

1. Administration of ethanol (14g/day per kg) for 21-26 days to rats increases the ability of the animals to metabolize ethanol, without concomitant changes in the activities of liver alcohol dehydrogenase or catalase. 2. Liver slices from rats chronically treated with ethanol showed a significant increase (40-60%) in the rate of O(2) consumption over that of slices from control animals. The effect of uncoupling agents such as dinitrophenol and arsenate was completely lost after chronic treatment with ethanol. 3. Isolated mitochondria prepared from animals chronically treated with ethanol showed no changes in state 3 or state 4 respiration, ADP/O ratio, respiratory control ratio or in the dinitrophenol effect when succinate was used as substrate. With beta-hydroxybutyrate as substrate a small but statistically significant decrease was found in the ADP/O ratio but not in the other parameters or in the dinitrophenol effect. Further, no changes in mitochondrial Mg(2+)-activated adenosine triphosphatase, dinitrophenol-activated adenosine triphosphatase or in the dinitrophenol-activated adenosine triphosphatase/Mg(2+)-activated adenosine triphosphatase ratio were found as a result of the chronic ethanol treatment. 4. Liver microsomal NADPH oxidase activity, a H(2)O(2)-producing system, was increased by 80-100% by chronic ethanol treatment. Oxidation of formate to CO(2)in vivo was also increased in these animals. The increase in formate metabolism could theoretically be accounted for by an increased production of H(2)O(2) by the NADPH oxidase system plus formate peroxidation by catalase. However, an increased production of H(2)O(2) and oxidation of ethanol by the catalase system could not account for more than 10-20% of the increased ethanol metabolism in the animals chronically treated with ethanol. 5. Results presented indicate that chronic ethanol ingestion results in a faster mitochondrial O(2) consumption in situ suggesting a faster NADH reoxidation. Although only a minor change in mitochondrial coupling was observed with isolated mitochondria, the possibility of an uncoupling in the intact cell cannot be completely discarded. Regardless of the mechanism, these changes could lead to an increased metabolism of ethanol and of other endogenous substrates.

Journal Article↗
PubMed1973

Metabolic alterations produced in the liver by chronic ethanol administration. Changes related to energetic parameters of the cell.

1. Chronic ethanol administration to rats for 21-27 days increases the rate of O(2) consumption as measured in liver slices. The extra respiration can be abolished by inhibition of the active transport of Na(+) and K(+). Dinitrophenol activates the respiratory rate in the liver of the treated animals only in the presence of ouabain. 2. Active (ouabain-sensitive) transport of (86)Rb and (Na(+)+K(+))-stimulated adenosine triphosphatase activity were increased in the livers of the ethanol-treated animals. 3. Chronic ethanol administration also led to a decrease in the phosphorylation potential ([ATP]/[ADP][P(i)]) in the liver cell owing to a decrease in [ATP] and an increase in [P(i)]. 4. It is suggested that an increased sodium pump activity is responsible for the increased oxidative capacity and for the insensitivity to dinitrophenol observed in the livers of ethanol-treated animals.

Journal Article↗
PubMed1973

Metabolic alterations produced in the liver by chronic ethanol administration. Comparison between the effects produced by ethanol and by thyroid hormones.

1. Liver slices from rats treated with thyroxine show an increased rate of O(2) consumption. The extra consumption, but not the basal respiration, can be abolished by ouabain. 2. Dinitrophenol is not effective in increasing the rate of O(2) consumption of liver slices from thyroxine-treated animals but its effectiveness can be recovered in the presence of ouabain. 3. (Na(+)+K(+))-stimulated adenosine triphosphatase activity of liver was increased by administration of thyroxine in vivo. No changes were found in total Mg(2+)-stimulated adenosine triphosphatase activity. 4. Mitochondrial alpha-glycerophosphate dehydrogenase and microsomal NADPH oxidase activity were increased by both thyroxine and chronic ethanol treatment. 5. Liver slices from animals chronically treated with ethanol synthesize urea at an increased rate. 6. Mitochondrial size (section area) is markedly increased in the liver of animals chronically treated with ethanol. 7. Acute administration of ethanol in doses of 4 and 6g/kg significantly increases the uptake of (131)I-labelled thyroxine by the liver. 8. Work reported here, along with results from other investigators, indicates marked similarities between the effects produced in the liver by chronic administration of ethanol and by thyroid hormones.

Journal Article↗
PubMed1972

Changes from high potassium (hk) to low potassium (lk) in bovine red cells.

Red cells of newborn calves contain 105-110 mmole K(+) and 1-5 mmole Na(+) per liter of cells. As the animals age the K(+) content decreases to a value of 25-30 mmole/liter of cells after about 60 days. At approximately the same time, the sodium content reaches a value of 60-70 mmole/liter. The time required for half change (t((1/2))) is 35-37 days for both Na(+) and K(+). The activity of (Na + K)-adenosine triphosphatase (ATPase) and the influx of K(42) and Rb(86) into the red cells are high at birth and are reduced to 5 and 15% of their original values, respectively, in mature animals. t((1/2)) for both is of the order of 30-35 days. The membrane Mg-ATPase activity is also high at birth and is reduced with a t((1/2)) of 28-32 days to a final value of about 20% of its activity at birth. Separation of red cells according to their age showed that, in animals at the age of transition, newly formed red cells contain a higher K/Na ratio and a higher active transport capacity than older red cells of the same animal. It is suggested that the changes observed are a reflection of the average age of the red cell population as the animal grows.

Adenosine Triphosphatases↗
PubMed1970

Factors that modify the metabolism of ethanol in rat liver and adaptive changes produced by its chronic administration.

1. 2,4-Dinitrophenol (0.1mm) increases by 100-160% the rate of ethanol metabolism by rat liver slices incubated in a medium saturated with a gas mixture containing O(2)+CO(2)+N(2) (18:5:77). Similar effects are produced by relatively low concentrations of arsenate (10mm). At higher concentrations (37.5 and 50mm) arsenate inhibits the rate of ethanol metabolism. 2. When liver slices are incubated under an atmosphere containing O(2)+CO(2) (95:5) the metabolism of ethanol increases by about 100% over that obtained with O(2)+CO(2)+N(2) (18:5:77). However, under these conditions the activating effect of dinitrophenol is no longer observed. 3. Chronic administration of ethanol to rats for 3-4 weeks, in doses from 3 to 8g/kg per day, increases by 70-90% the ability of the liver to metabolize ethanol. In the liver slices of these rats, although an O(2)+CO(2)+N(2) (18:5:77) mixture was used, dinitrophenol does not further increase the metabolism of ethanol. If the chronic administration of ethanol is discontinued for two weeks, the rate of ethanol metabolism is lowered to control values and the activating effect of dinitrophenol is recovered. 4. No change in alcohol dehydrogenase activity was found in the liver of the rats in which the metabolism of ethanol had been increased as a result of the chronic ethanol treatment; a 40% increase in the activity of succinate dehydrogenase was observed.

Alcohol Oxidoreductases↗