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Biomedical subjects

M Hirata

Publications and source records attributed to M Hirata.

At least 685 records · Page 38Linked to original sources
PubMed1978

Coronary vasospastic action of thromboxane A2 in isolated, working guinea pig hearts.

The effects of thromboxane A2 (TXA2) on isolated, working guinea pig heart and left ventricular papillary muscle preparations were investigated. TXA2 was generated by the enzymatic conversion of prostaglandin H2 (PGH2) with indomethacin-treated horse platelet microsomes (IPM). TXA2 caused dose-dependently a considerable decrease in the coronary flow, left ventricular systolic pressure and left ventricular dp/dt in the perfused heart, while the similar effects of PGH2 were transient and weaker than those of TXA2. These effects of TXA2 disappeared after the TXA2-generating system was left standing at 37 degree C for 3 min. When IPM in the TXA2-generating system was pretreated with a TXA2 synthetase inhibitor, L-8027, the enhanced cardiac responses induced by the mixture of IPM and PGH2 disappeared. TXA2 had no direct effect on the contractile force of the papillary muscle. These results suggest that TXA2 has a specific coronary vasopastic action without a direct inotropic effect.

Animals↗
PubMed1978

Neutral proteases in the guinea-pig lymphocytes.

Partial purification of neutral proteolytic enzymes in guinea-pig lymphocytes yielded 2 enzymes. Both enzymes were heat-labile and inhibited by thiol reagents. The molecular weights were more than 200,000 and 150,000-200,000, and optimal pH around 9 and 8, respectively.

Animals↗
PubMed1978

Reconstruction of the superior vena cava in a patient with a thymoma.

Surgical treatment was attempted in a 71-year-old man who had superior vena caval syndrome caused by incomplete obstruction of the superior vena cava with a thymoma. Using a temporary internal shunt, the superior vena cava was almost entirely resected together with the tumor and reconstructed by autogenous venous grafts. Patency of the reconstructed vein was proved by angiography one year after the operation. He has been asymptomatic for 15 months after surgery.

Aged↗
PubMed1977

Ca2+ regulation in vascular smooth muscle.

Regulation of aorta smooth muscle contraction by Ca ion requires the collaboration of the 80,000 dalton factor and tropomyosin. A method for preparing pure actin from aorta smooth muscle is described.

Actins↗
PubMed1977

Effects of a 2-substituted adenosine derivative, 2-(p-methoxyphenyl)-adenosine (CV-1674) on coronary and cardiohemodynamics, and myocardial energetics.

In dogs, intracoronary doses of CV-1674, adenosine ( ADS) and 2-Cl-ADS for doubling coronary flow were estimated as 5.0, 2.0 and 0.4 microgram/dog, and i.v. doses 31, 71 and 2.5 microgram/kg, respectively. ADS and 2-Cl-ADS decreased, while CV-1674 increased LV dp/dt. Intravenous infusion (30 min) of CV-1674 (10 microgram/kg per min) and ADS (700 microgram/kg per min) decreased coronary resistance to approximately the same extent. Decreases in blood pressure, total peripheral resistance and myocardial O2 concumption with ADS were more prominent than those with CV-1674. ADS produced a marked bradycardia that was not evident with CV-1674. Neither agent had a significant influence on myocardial efficiency. In guinea pig atria, ADS and 2-Cl-ADS exerted negative effects while those with CV-1674 were positive inotropic and chronotropic. In cats, intraduodenal ADS (10 mg/kg) produced no effects on cardiohemodynamic parameters. CV-1674 (250 and 500 microgram/kg) increased myocardial tissue blood flow (MBF) with a slight hypotension in a dose-dependent manner, whereas 2-Cl-ADS (100, 250 and 500 microgram/kg) increased MBF only with the highest dose concomitantly with marked hypotension and bradycardia. These results suggest that CV-1674 induces selective coronary vasodilation with less depression on cardiohemodynamics, and is relatively well absorbed from the intestinal tract. The pharmacological profile of the compound, therefore, differs from that of ADS and 2-Cl-ADS.

Adenosine↗