Responsiveness of monkey skeletal muscle arteries to vasoconstrictor substances before and after cold storage.

Abstract

The stainless steel cannula inserting method was used to observe effects of .alpha.-adrenoceptor agonists, 5-HT and KCl before and after cold storage (3-5 days, at 4.degree.C) in skeletal muscle branches of the simian deep femoral artery. Epinephrine (EPI), norepinephrine (NE), phenylephrine (P.E), methoxamine (MT) and 5-hydroxytryptamine (5-HT) induced marked monophasic vasoconstrictions in a dose-dependent manner. 5-HT induced a greater vasoconstriction in larger diameter vessels (old animals) than that in smaller ones (young animals), suggesting age-related responses. A selective .alpha.2-stimulant, clonidine (CLO) or xylazine (XYL), produced only a slight vasoconstriction. Tyramine (TYR) also produced only a slight vasoconstrictor response. The older of potencies for inducing vasoconstrictions was EP I .gtoreq. 5-HT .gtoreq. NE > MT = PE .mchgt. KCl > CLO = XYL = TRY. The vasoconstrictor responses to all used adrenergic agonists and 5-HT were not significantly influenced by the prolonged cold storage. However, KCl-induced constrictions were significantly suppressed by the cold storage. These results suggest that the postjunctional .alpha.-adrenoceptor in simian skeletal muscle arteries is mainly of the .alpha.1-type. Since cold storage caused a significant suppression of the KCl-induced response but not those of adrenoceptor agonists and 5-HT, it was considered that the mechanism of calcium entry to the vascular smooth muscle of skeletal muscle arteries might be significantly damaged by the cold storage.