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Biomedical subjects

T Suga

Publications and source records attributed to T Suga.

At least 361 records · Page 20Linked to original sources
PubMed1978

[Research on the contracting and relaxant actions of cardiac steroids on the taenia coli of guinea pig (author's transl)].

Actions of cardiac steroid (CS) such as bufadienolides and cardenolides, on guinea pig taenia coli were studied using the double sucrose-gap method. When an appropriate dose of CS was applied, the taenia coli first contracted, then relaxed. After removal of CS, the relaxation was enhanced and continued for 20-40 min. In decreasing order of the relaxant action were bufalin, ouabain, cinobufagin and resibufogenin. Further application of CS after occurrence of the relaxation induced a secondary gradual contraction. The contraction occurred with the membrane depolarization and increase in spike discharge, and the relaxation corresponded fairly well with decrease in spike discharge and the membrane repolarization. Membrane resistance was decreased during the contraction as well as the relaxation. The decrease in membrane resistance continued during the relaxation after removal of CS, Na, K and Ga conductances were increased by CS application, respectively. The increase of Na conductance was relatively high during the contraction, and the increase of K conductance was remarkable during the relaxation and after removal of CS. From the foregoing results it is considered that the contracting action is due to inhibition of the Na pump and that the relaxant action is due to the change in electrical properties of membrane produced by a marked increase in intracellular Na and the increase of K permeability. The relaxation after removal of CS is considered to be due to the activated electrogenic Na pump as indicated from the changes in electrical properties of membrane.

Action Potentials↗
PubMed1977

Studies of peroxisomes. VIII. Evidence for framework protein of the cores of rat liver peroxisomes.

The cores of peroxisomes were purified 670 fold from a rat liver homogenate and the protein in the preparation was examined by sodium dodecyl sulfate(SDS)-polyacrylamide gel electrophoresis. Two bands of protein were detected on 10% polyacrylamide gel, and their molecular weights were calculated to be about 32,000 and 27,000. On treatment of the core fraction with alkali, urate oxidase was solubilized and on 10% polyacrylamide gel this fraction gave a single band of protein with an estimated molecular weight of 32,000. These results suggests that the protein component having a molecular weight of 27,000 is the framework protein of the core of rat liver peroxisomes.

Animals↗
PubMed1976

Effect of premedication of coenzyme Q10 on pancreozymin-induced pancreatic secretion in rats.

Effect of Coenzyme Q10 (CoQ10), an essential coenzyme in oxidative phosphorylation in the mitochondria, was studied in the rat's pancreas. A dose of pancreozymin (0.2 u/100 g body wt) was injected into the femoral vein at 20 min intervals. The initial injection produced a definite increase in amylase output and the pancreatic juice flow. Subsequent injections, however, caused smaller responses than the preceding (tachyphylaxis). When CoQ10 (3 mg/100 g body wt) had been administrated 1 hour prior to the initial stimulation, both the amylase output and the rate of juice flow were significantly enhanced: the tachyphylaxis almost disappeared. Effect of CoQ10 was also observed in the isolated and perfused pancreas. CoQ10 produced slight increase in pancreozymin-induced amylase output, but the increase was not significant. The effect of CoQ10, to increase the pancreatic blood flow, seems to be involved in the in situ effect of CoQ10 in cooperation with the direct effect on pancreatic acinar cells.

Amylases↗
PubMed1976

Studies on peroxisomes. VI. Relationship between the peroxisomal core and urate oxidase.

The peroxisomal core from the liver of rats was purified 450-fold as a marker of urate oxidase [EC 1.7.3.3.] activity. This preparation has a high specific activity of urate oxidase but not of other peroxisomal enzymes: D-amino acid oxidase [EC 1.4.3.3.], L-alpha-hydroxy acid oxidase [EC 1.1.3.15], or catalase [EC 1.11.1.6]. No activity of marker enzymes for other subcellular particles; cytochrome c oxidase [EC1.9.3.1] (mitochondria), acid phosphatase [EC 3.1.3.2] (lysosomes), or glucose-6-phosphatase [EC 3.1.3.9] (microsomes), was detected in this preparation. The core obtained showed a single protein band in sodium dodecyl sulfate-polyacrylamide gel electrophoresis and the position of the band was found to correspond to a molecular weight 35,000. When the peroxisomal core was subjected to treatment at various pH's with 0.1 M carbonate buffer, urate oxidase was almost completely solubulized at pH 11.0, although approximately 35% of the core protein still remained in the pellet After solubilization of the core at pH 11.0, the specific activity of urate oxidase in the supernatant increased about 1.6 times; the density of the insoluble protein remaining in the pellet was identical with the that of the original core on sucrose density gradient centrifugation.

Animals↗
PubMed1976

Reduction of the hypoxia-induced depression in the intracellular electrical activity of the ventricular muscle fibers of the rabbit fed on food containing Crataegutt.

The rabbits were divided at random into 2 groups: one was fed for 6 weeks on the rabbit food containing 5 mg Crataegutt per 100 Gm food (CR group), and the other was fed for the same period on the commercial rabbit food and used as a control. Intracellular records were made from fibers in the ventricle of isolated rabbit heart. The inhibitory influences of hypoxia on the resting membrane potential and on the amplitude of action potential of the fiber of the CR group are significantly less than those of the control group. However, the inhibitory influence on the time courses of contraction of the papillary muscle was almost the same between these 2 groups.

Action Potentials↗
PubMed1976

Effects of oxygen supply on electrical and secretory responses of humorally stimulated acinar cells in isolated rat pancreas.

A technique is described for perfusing isolated rat pancreas with a modified Krebs-Henseleit solution. This preparation made feasible the simultaneous measurement of transmembrane potential, effective membrane resistance, rate of flow of pancreatic juice and amylase output. The hyperpolarizing effect of cholecystokinin-pancreozymin (CCK-PZ) was confirmed by perfusion with a solution containing 5 mU CCK-PZ/ml. The hyperpolarizing efffect of CCK-PZ was enhanced when the pancreas was perfused with an oxygenated solution containing dog erythrocytes. This effect was inhibited by ouabain and anaerobic conditions. It is suggested that the oxidative metabolism supplies energy for a mechanism which is responsible for the hyperpolarizing effect of CCK-PZ. The amylase output and the rate of flow of pancreatic juice were enhanced concurrently under conditions that augumented the hyperpolarizing effect, and they were inhibited under conditions that suppressed the effect. Cellular events in stimulus-secretion coupling in the pancreatic acinar cell are discussed by correlating the electrophysiological responses and the secretory responses under various conditions.

Amylases↗
PubMed1975

Studies on peroxisomes. V. Effect of ethyl p-chlorophenoxyisobutyrate on the centrifugal behavior of rat liver peroxisomes.

After Wistar male rats had been fed on a diet containing 0.25% of ethyl p-chlorophenoxyisobutyrate (CPIB) for 28 days, changes in the enzyme activities and centrifugal behavior of rat liver peroxisomes were investigated. (1) Compared with control rats fed on the basal diet, the catalase [EC 1.11.1.6] activity of rat livers after the administration of CPIB increased about 2.5-fold, while urate oxidase [EC 1.7.3.3] activity did not change significantly. Though D-amino acid oxidase [EC 1.4.3.3] activity markedly decreased to approximately one-sixth of the control, the activity of L-alpha-hydroxy acid oxidase [EC 1.1.3.15], a flavin enzyme like D-amino acid oxidase, was not affected significnatly after the administration of CPIB. (2) When the hepatic cells of CPIB-treated rats were fractionated by differential centrifugation, most of the increase of catalase activity appeared in the supernatant fraction. A decrease in the hepatic D-amino acid oxidase activity of CPIB-treated rats was observed in all the fractions. As for the subcellular distribution of the particle-bound enzymes, the specific activities of both catalase and urate oxidase of CPIB-treated rat livers were higher in the light mitochondrial fraction than in other fractions. (3) Sedimentation patterns in a sucrose density gradient did not show any difference between normal peroxisomers, and CPIB-treated ones. (4) In the case of CPIB-treated rats, studies of their sedimentation patterns by Ficoll density gradient centrifugation showed two main particulate peaks containing both catalase and urate oxidase, although only a single peak was observed in the case of control rats.

Alcohol Oxidoreductases↗