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Biomedical subjects

S Takeo

Publications and source records attributed to S Takeo.

At least 199 records · Page 11Linked to original sources
PubMed1980

Effects of dl-erythro-1-phenoxy-3-[(3,4-dimethoxyphenethyl)-amino]-butan-2-ol (PS-6) on rat heart sarcolemma.

Effects of dl-erythro-1-phenoxy-3-[(3,4-dimethoxyphenethyl)-amino]-butan-2-ol (PS-6) on ATPase and calcium binding activities of rat heart sarcolemma as well as adenylate cyclase of both sarcolemma and heart washed particles were studied under in vitro conditions. PS-6 at concentrations of 10(-7) mol/l or higher inhibited Na+-K+ ATPase and calcium binding activities significantly. The inhibition of calcium binding activity was dependent upon the concentration of calcium in the incubation medium with greater percentage inhibition seen at lower concentrations. While basal adenylate cyclase activity was not affected by 10(-7)--10(-4) mol/l, isoprenaline stimulated adenylate cyclase activity was inhibited by 10(-6) mol/l or higher concentrations of PS-6. At 10(-3) mol/l PS-6 a more generalized inhibitory effect was seen, with all parameters studied being inhibited. These results suggest that sarcolemma is one of the sites for the cardiac actions of PS-6.

Adenosine Triphosphatases↗
PubMed1980

Effects of adrenochrome on calcium accumulating and adenosine triphosphatase activities of the rat heart microsomes.

The influence of adrenochrome (1-100 microgram/ml or 5.6 x 10(-6)-5.4 x 10(-4) M) on microsomal calcium binding, calcium uptake and Ca++-stimulated Mg++-dependent adenosine triphosphatase (ATPase) activities was studied in vitro. Adrenochrome decreased microsomal calcium binding, calcium uptake and Ca++-stimulated Mg++-dependent ATPase activities. The inhibitory effect of adrenochrome on microsomal calcium uptake activity of the isolated membrane was independent of pH (6.0-8.0), calcium concentrations (10-200 muM), protein concentration (0.02-0.10 mg/ml), temperature (25-37 degrees C) and incubation time (2-30 min). Kinetic study of calcium uptake activity in different concentrations of ATP showed that the inhibition was of a mixed type. Perfusion of hearts with adrenochrome resulted in marked depression in contractile force and the microsomal fraction obtained from these hearts showed depressed calcium binding, calcium uptake and Ca++-stimulated Mg++-dependent ATPase activities. The depression in microsomal The influence of adrenochrome (1-100 microgram/ml or 5.6 x 10(-6)-an irreversible nature. It is proposed that cardiodepressant action of adrenochrome may partly be explained on the basis of its inhibitory effect on the calcium transporting ability of the sarcoplasmic reticulum.

Adrenochrome↗
PubMed1979

Effects of lanthanum on the heart sarcolemmal ATPase and calcium binding activities.

Effects of lanthanum on Ca2+-ATPase, Mg2+-ATPase, Na+-K+-ATPase, and calcium binding activities were studied in rat heart sarcolemma. Ten to 100 micrometers lanthanum depressed significantly the Ca2+-ATPase activity and 50--200 micrometers lanthanum inhibited the calcium binding activity. Lineweaver-Burk plots of the Ca2+-ATPase activity showed that the inhibition by lanthanum was competitive with calcium concentration. Neither Mg2+-ATPase nor Na+-K+-ATPase activities were affected by lanthanum when the assay medium contained 1 mM EDTA; however, in the absence of EDTA, these enzyme activities were significantly decreased by 10--100 micrometers lanthanum. Rat hearts perfused with HEPES buffer containing 0.5 mM lanthanum showed electron-dense deposits restricted to the outer cell surface and the sarcolemma obtained from these hearts also had the deposits, indicating that the membrane fraction isolated by the hypotonic shock--LiBr treatment method is of sarcolemmal origin. The Ca2+-ATPase activity of the sarcolemma isolated from lanthanum-perfused hearts, unlike the Mg2+-ATPase, Na+-K+-ATPase, and calcium binding activities, was significantly less than the control value. From these observations it is suggested that lanthanum may influence calcium movement across the sarcolemma by affecting sarcolemmal ATPase and calcium binding activities.

Adenosine Triphosphatases↗
PubMed1978

[Effects of Theo-Esberiven on the coronary circulation and myocardial metabolisms in dogs (author's transl)].

In isolated dog heart, Theo-Esberiven 0.1 mg, which contains 12 mg proxyphylline, 2.5 mg rutin and 5 mg Melilotus extract, and proxyphylline (12 mg) increased coronary blood flow (CBF) and was associated with increased heart rate (HR) and myocardial contractile force (MCF). The effect of Theo-Esberiven on CBF was about 1.7 times higher than that of proxyphylline. Theo-Esberiven did not significantly affect myocardial oxygen consumption (QO2) and redox potential (deltaEh), while proxyphylline aggravated myocardial metabolisms, as determined from these parameters. Esberiven 0.1 ml, which contains 2.5 mg rutin and 5 mg Melilotus extract, slightly but signficantly increased CBF and decreased QO2 and deltaEh without changing HR and MCF. In situ, intra-coronary injection of either Theo-Esberiven or proxyphylline resulted in a dose-dependent increase in left circumflex coronary flow (LCCF). The effect of Esberiven on LCCF was much less and was slight at the higher doses. Intravenous injection of Theo-Esberiven (0.1 ml/kg) increased LCCF. Besides this change, marked fall in blood pressure and tachycardia were induced by both Theo-Esberiven and proxyphylline without the change in dP/dtmax. Esberiven by the same route led to the decrease in blood pressure associated with HR and dP/dtmax. These results indicate that Theo-Esberiven may be appropriately prescribed for ischemic heart diseases.

Action Potentials↗
PubMed1978

Comparison of myocardial and adipose tissue lipase activity in the rat.

Effects of catecholamines and iodoacetamide on lipase activity (pH 6.8) and triglyceride mobilization were investigated in adipose tissue, myocardial slice and isolated perfused heart preparation of the rat. Epinephrine and isoproterenol did not enhance myocardial lipase activity in vitro and in perfused hearts. No detectable amount of fatty acid was released from myocardial slice by epinephrine in vitro. Epinephrine, however, induced an increase in lipase activity and in the amount of fatty acid released from the adipose tissue. The results suggest a difference in properties of lipase present in the myocardium and in the adipose tissue. Iodoacetamide decreased lipase activity in vitro both in the myocardium and in the adipose tissue. Triglyceride content in the perfused heart receiving iodoacetamide at 30 min of perfusion was higher than that of the control. However, there was no correlation between triglyceride mobilization and lipase activity in these 2 tissues.

Adipose Tissue↗
PubMed1978

Effects of dobutamine on coronary circulation and cardiac metabolism of the dog.

Effects of (+/-)-4-[2-(3-p-hydroxyphenyl-1-methyl-amino)ethyl]pyrocatechol (dobutamine) on coronary circulation and cardiac metabolism were investigated using the heart in vivo and the isolated perfused heart of dogs. In the heart in vivo dobutamine 1--30 microgram/kg i.v. and 1--100 microgram i.c. produced dose-dependent increases in coronary perfusion pressure, coronary blood flow, heart rate and left intraventricular pressure. In the perfused heart dobutamine 10 microgram i.c. increased coronary flow, heart rate, cardiac contractility and myocardial oxygen consumption. Delta redox potentials decreased but did not show negative values. Propranolol 0.1 mg/kg i.v. and 0.1 mg i.c. inhibited these effects of dobutamine. Dobutamine shows basically the same actions as isoproterenol, but does not reduce the coronary perfusion pressure by the relatively high dose applied. The results suggest that dobutamine may have a selective adrenergic beta 1 receptor stimulating action on the heart and have a merit in maintaining the coronary perfusion pressure.

Animals↗
PubMed1978

Comparison of lactate pyruvate and potassium concentration in the cardiac lymph and, arterial and coronary sinus plasma in dogs.

Lactate (LA), pyruvate (PYR) and potassium (K) concentration in the cardiac lymph were compared with those in the arterial and coronary sinus plasma in dogs. In each substance, there was a good correlation between the plasma and cardiac lymph level in the control period. In respect to LA and PYR, the concentration in the cardiac lymph correlated more with that in the arterial plasma than in the coronary sinus one. During the infusion of isoproterenol, LA and PYR in the plasma increased, while K decreased. Each substance in the cardiac lymph changed to the same degree as in the plasma in mean values. Good correlation was also observed between the arterial plasma and cardiac lymph level during the administration of the agent. However, there was no correlation of PYR between the coronary sinus plasma and the cardiac lymph. During the administration of dipyridamole LA in the coronary sinus plasma increased and that in the arterial plasma decreased. LA in the cardiac lymph did decrease as in the arterial plasma. It is concluded that the concentrations of LA, PYR and K in the cardiac lymph can be changed depending upon changes in those in the plasma and the former two parameters seem to change depending upon those in the arterial plasma rather than the coronary sinus one.

Animals↗
PubMed1977

Effects of diltiazem on high-energy phosphate contents reduced by isoproterenol in rat myocardium.

Effects of diltiazem on myocardial high-energy phosphate metabolism as well as on arterial blood pressure and heart rate were investigated in the rat treated with isoproterenol. Pretreatment with diltiazem prevented the reduction in both adenosine triphosphate and creatine phosphate induced by 2.5 mg/kg of isoproterenol. The ratio of creatine phosphate/inorganic phosphate in the rat receiving 100 mg/kg of diltiazem was higher than in the control. Heart rate was significantly decreased by the administration of 100 mg/kg of diltiazem not only in the non-pretreated rat but also in the rat given isoproterenol. This may partly account for the protective effect of diltiazem against the breakdown of high-energy phosphate in the isoproterenol-treated rat.

Adenosine Triphosphate↗
PubMedDate not supplied

Myocardial fatty acid and cardiac performance.

Isoproterenol enhanced myocardial triglyceride utilization and incorporation of exogenous fatty acid into triglyceride fraction in the perfused rat heart in the presence of glucose. However, in the absence of glucose, cardiac performance was considerably aggravated by isoproterenol. This suggests that glucose might be an essential fuel in the heart stimulated by isoproterenol.

Animals↗
PubMedDate not supplied

Metabolic profile of beta-adrenoceptor-blocking action of befunolol.

The present study was undertaken to elucidate the metabolic profile of the beta-blocking effects of befunolol on catecholamine-induced changes in plasma glucose, lactate and free fatty acid concentrations and myocardial metabolism. Effects of propranolol were also tested for the purpose of comparison. Epinephrine, at doses of 0.2 to 0.35 mg/kg, induced significant increases in the plasma glucose, lactate and free fatty acid concentrations. These changes were inhibited by pretreatment with either befunolol or propranolol at doses of 0.03 mg/kg or above. Isoproterenol-induced changes in systemic blood pressure and heart rate were reduced by pretreatment with intravenous injection of 10 and 100 micrograms/kg of bufunolol and 100 micrograms/kg of propranolol. Isoproterenol-induced changes in myocardial ATP, creatine phosphate, lactate and cyclic AMP were also reduced by pretreatment with 10 and 100 micrograms/kg of befunolol and 100 micrograms/kg of propranolol. Propranolol, at a dose of 10 micrograms/kg, did not reduce isoproterenol-induced changes in heart rate, blood pressure, and in myocardial ATP, creatine phosphate and cyclic AMP contents. The results demonstrate that befunolol exerts an inhibitory action on catecholamine-induced hemodynamic and metabolic alterations, and provide further evidence for the beta-blocking action of this drug.

Adenosine Triphosphate↗