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Biomedical subjects

E Hayashi

Publications and source records attributed to E Hayashi.

At least 145 records · Page 8Linked to original sources
PubMed1980

Effect of l-ascorbate 2-sulfate on fatty liver and hyperlipidemia induced by various treatments in rats and guinea pigs.

Effects of L-ascorbate 2-sulfate (AAS) on fatty liver and hyperlipidemia induced by various treatments were studied in rats and guinea pigs. L-Ascorbic acid (AA) (50 or 175 mg/kg), a reference compound, lowered the lipid levels in the serum and/or liver in guinea pigs, while AA had little effect in rats. On the other hand, AAS (300 mg/kg) was effective in both animals. In rats, AAS lowered cholesterol and triglycerides in the serum from ethionine-treated animals and in the liver from orotic acid-supplemented animals. In guinea pigs, this compound lowered cholesterol and triglycerides in the serum from ethionine-treated animals, lipids in the liver from cholesterol-supplemented animals, and lipids in the serum and liver from scorbutic animals. AA markedly increased the content of AA in the organs in all experiments, while AAS had a slight effect. Thus, it is suggested that AAS exerts its hypolipidemic and lipotropic effects by the specific actions of AAS.

Animals↗
PubMed1980

[The specificity of pharmacological responses in Ascaris muscle (author's transl)].

To investigate the pharmacological properties of Ascaris muscle, comparative studies were undertaken on the actions of various drugs on Ascaris muscle, guinea pig isolated ileum and frog isolated rectus preparations. In Ascaris muscle and frog isolated rectus preparations, the contractile activities with acetylcholine (ACh, 10(-5) g/ml in Ascaris and 10(-6) g/ml in frog rectus) and 1, 1-dimethyl-4-phenylpiperazinium (DMPP, 10(-6) g/ml) were inhibited significantly and reversely by d-tubocurarine (d-Tc, 10(-5) g/ml) and mecamylamine (Meca, 10(-5) g/ml), and slightly by atropine (Atr, 10(-4) g/ml) and hexamethonium (C6, 10(-4) g/ml). In guinea pig isolated ileum preparation, the contractile activity with ACh (10(-6) g/ml) was inhibited markedly and reversely but Atr (10(-6) g/ml), while the activity with DMPP (10(-6) g/ml) was similarly inhibited by Meca (10(-6) g/ml), C6 (10(-6) g/ml) and Atr (10(-6) g/ml). Although frog isolated rectus preparation was contracted with 4-(m-chlorophenylcarbamoyloxy)-2-butynyltrimethylammonium (McN-A-343, 10(-5) g/ml) but not with pilocarpine (10(-4) g/ml), Ascaris muscle preparation was not affected by these agonists. Frog isolated rectus preparation was contracted with 5-hydroxytryptamine (5 HT, 10(-4) g/ml) but was not affected by histamine (His, 10(-3) g/ml) and gamma-aminobutyric acid (GABA, 10(-4) g/ml), whereas Ascaris muscle was contracted with His (10(-3) g/ml) and relaxed with 5-HT (10(-4) g/ml) and GABA (10(-5) g/ml). These results suggest that Ascaris muscle as well as skeletal muscle have nicotinic receptors and that the Ascaris muscle has properties which differ specifically from skeletal muscle.

Acetylcholine↗
PubMed1980

Age and blood pressure related changes in cholesterol esterase activity and cholesterol content in aortas of stroke prone spontaneously hypertensive rats, spontaneously hypertensive rats and normotensive Wistar Kyoto rats.

Changes in aortic lipolytic enzyme activities (cholesterol esterase and lipoprotein lipase) and acid phosphatase activity during aging were investigated in three strains of rats with different blood pressures; stroke prone spontaneously hypertensive rats (SHRSP), spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto (WKR). The blood pressures of male, 7 month old animals, was 234 (SHRSP), 173 (SHR) and 128 (WKR) mmHg. The cholesterol esterase activity markedly decreased with age in the aortas of SHRSP, SHR and normotensive WKR rats, while acid phosphatase activity decreased only slightly, if at all, and lipoprotein lipase activity remained unchanged. This effect was enhanced by increasing blood pressure in SHRSP, SHR and WKR. The total aortic cholesterol content increased significantly with hypertension in a inverse relation with cholesterol esterase activity. These results suggest that cholesterol deposition in aged arteries is, at least partialy, ascribable to an age-related decrease in cholesterol esterase, and that hypertension aggravates the deposition of arterial cholesterol by accelerating the age-related decrease in aortic cholesterol esterase activity.

Acid Phosphatase↗
PubMed1979

Changes in intracellular activities of lysosomal enzymes in tissues of rats during aging.

A comparison of results obtained from studies of the intracellular fractions of the tissues of liver, brain and heart of "young" (1-2 months), "old" (24-27 months) and "senile" (34-37 months) rats showed that the ratios of three enzymes, acid phosphatase, beta-N-acetylglucosaminidase and acid RNase of the liver and heart were very similar and their activities decreased with age. On the other hand, the protein content is the supernatant of the liver, and acid DNase activities in the supernatant of the brain increased significantly with age. When the 24-27 month and 34-37 month old rats were compared, the ratios of the total activities of liver beta-N-glucosaminidase and brain acid DNase in the supernatant and the specific activities of brain beta-N-glucosaminidase in the microsomal fraction increased significantly.

Acid Phosphatase↗
PubMed1979

Effects of surugatoxin on adrenergically innervated tissues.

Effects of surugatoxin (SGTX), a new ganglionic blocking agent on adrenergically innervated tissues: guinea pig isolated atria and vas deferens were investigated. SGTX (1, 10 muM) markedly reduced the cardiostimulatory response of the atria to nicotine and also partially the response to 1,1-dimethyl-4-phenylpiperazinium (DMPP) and 5-hydroxytryptamine, without affecting responses to noradrenaline, tyramine and histamine. The contractile response of the vas deferens to nicotine, DMPP and hypogastric nerve stimulation was markedly reduced by SGTX (1, 10 muM), whereas that to noradrenaline, acetylcholine and transmural stimulation was not affected. These results indicate that SGTX has an antagonistic action on nicotinic receptors in these tissues as well as in sympathetic ganglia and in guinea pig ileum.

Animals↗
PubMed1979

Neutral lipid accumulation in yeast due to inositol deficiency: kinetic studies on the reciprocal regulation by fructose bisphosphate and citrate of yeast acetyl CoA carboxylase.

Neutral lipids, especially triacylglycerols, accumulated due to myo-inositol deficiency both in the cells of Saccharomyces carlsbergensis (Hayashi et al. (1976) J. Biol. Chem., 251, 5759--5769) and in the liver of the rat (Hayashi et al. (1974) Biochim. Biophys. Acta, 360, 134--155). The accumulation of triacylglycerols in the deficient yeast resulted, at least partly, from an enhancement of acetyl CoA carboxylase activity. The activation of the enzyme reflected the fluctuation due to the deficiency in the levels of fructose bisphosphate and citrate (Hayashi et al. (1978) Biochim. Biophys. Acta, 540, 231--237). Thus, the kinetics of the regulation of acetyl CoA carboxylase by these intermediates was studied. In physiological concentrations fructose bisphosphate sigmoidally activated acetyl CoA carboxylase from yeast with the Hill coefficient of 3, while citrate counteracted the fructose bisphosphate activation in a sigmoidal manner with the Hill coefficient of 2. Fructose bisphosphate markedly increased the apparent Vmax value of acetyl CoA carboxylase for the substrate, ATP and slightly decreased the apparent Km value. Citrate greatly decreased the apparent Vmax value increased by fructose bisphosphate.

Acetyl-CoA Carboxylase↗
PubMed1979

Effects of phthalazinol (EG 626) on arterial lipolytic enzyme activities in the rat.

Phthalazinol (EG 626), a thromboxane A2 antagonist and cyclic AMP phosphodiesterase inhibitor, has been shown to prevent the atherosclerosis induced in cholesterol fed rabbits. In an attempt to clarify the antiatherosclerotic mechanism, the effects of this compound on the lipolytic enzyme activities (cholesterol esterase and lipoprotein lipase) of rat aorta were examined in vivo. Administration of EG 626 (100-200 mg/kg, per os, daily, 1-2 weeks) affected neither the aortic lysosomal cholesterol esterase nor the acid phosphatase activity, whereas the lipoprotein lipase activity was signficantly decreased by the treatment. These results suggest that with an elevation in HDL-cholesterol, a decrease in lipoprotein lipase activity after ingestion of EG 626 might contribute, at least to some extent, to the prevention of arterial lipid accumulation.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1979

An alteration in sensitivity to cholinergic agents on guinea-pig ilea and atria after repeated administration of an organophosphate and an antagonism by a carbamate.

The effect of 4-methylthiophenyl dipropylphosphate (propaphos, organophosphorus insecticide) and 2-sec-butylphenyl-N-methylcarbamate (BPMC, carbamate insecticide) on the sensitivity to the effects of acetylcholine (ACh), carbachol (CCH) and nicotine was investigated on guinea-pig isolated ilea and atria. The response of these tissues to ACh was significantly enhanced in the presence of propaphos (3.3 x 10(-7) M) or BPMC (4.5 x 10(-6) M), while that to CCH was unaffected. The repeated administration of propaphos (5 mg/kg/day, p.o.) for 7 days had no effect on the contractile responses of guinea-pig ilea to potassium chloride. The responses of ilea and atria to ACh and nicotine were markedly increased by the administration of propaphos, and the values of ED50 and ED80 for their responses were significantly decreased. On the other hand, the response to CCH was decreased as was demonstrated by a significant increase in these values. Pretreatment with BPMC (25 mg/kg/day p.o., 7 days) significantly reduced the alteration in the responsiveness of the tissues to ACh, CCH and nicotine produced by the propaphos administration. The activity of cholinesterase (ChE) declined by 50--70% in blood and tissues from propaphos-treated animals, and its inhibition was significnatly reduced by the pretreatment with PBMC to 30--40%. These results indicate that changes in synaptic ChE activity, as reflected by the changes in ChE activity of blood and tissues, may be responsible for the alteration in sensitivity of ilea and atria to cholinergic agents produced by the repeated administration of propaphos and for the antagonism by BPMC.

Acetylcholine↗
PubMed1978

The effect of myo-inositol deficiency on lipid metabolism in rats. III. The mechanism of an enhancement in lipolysis due to myo-inositol deficiency in rats.

myo-Inositol deficiency in rats produced an overaccumulation of triacylglycerols in the liver due to stimulated lipolysis in the adipose tissue (Hayashi, E., Maeda, T. and Tomita, T. (1974) Biochim. Biophys. Acta 360, 134--155). The mechanism of the enhancement in lipolysis has now been investigated. The lipolytic response to adrenalin, corticotropin and insulin of the epididymal adipose tissue did not change due to the deficiency, but hormone-sensitive lipase activity, plasma adrenalin level and blood pressure were higher in the deficient rats. Adrenalectomy had no influence, but administration of sympathetic nervous blockers (reserpine, hexamethonium and bupranolol) inhibited the liver lipid deposition and an increase of serum free fatty acids in the deficient rats. These results indicate that the enhancement in lipolysis is mediated by an excitation of sympathetic nerve terminals innervating in the adipose tissues.

Adipose Tissue↗
PubMed1978

The fluctuation of various enzyme activities due to myo-inositol deficiency in Saccharomyces carlsbergensis.

The neutral lipid accumulation in myo-inositol deficient Saccharomyces carlsbergensis results at least partly from an enhancement of acetyl CoA carboxylase activity due to the high level of fructose 1,6-biphosphate which activates acetyl CoA carboxylase, and due to the low level of citrate which counteracts the activation [4]. In an attempt to explore the effect of myo-inositol deficiency on the metabolic fluxes, various enzyme activities were compared between the myo-inositol supplemented and deficient cells. The activities of phosphofructokinase and ATP-citrate lyase increased by 74 and 83%, respectively. The activity of glucose-6-phosphate dehydrogenase was unchanged. Unlike acetyl CoA carboxylase, elimination of low molecular effectors had no influence on their activities. The thermostability of phosphofructokinase (at 53 degrees C) increased, while that of aldolase (at 48 degrees C) greatly decreased due to the deficiency. The thermostability of glucose-6-phosphate dehydrogenase (at 52 degrees C) was also unchanged.

ATP Citrate (pro-S)-Lyase↗