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

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 degrees C) in skeletal muscle branches of the simian deep femoral artery. Epinephrine (EPI), norepinephrine (NE), phenylephrine (PE), 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 order of potencies for inducing vasoconstrictions was EPI greater than or equal to 5-HT greater than or equal to NE greater than MT = PE much greater than KCl greater than CLO = XYL = TYR. The vasoconstrictor responses to all used adrenergic agonists and 5-HT were not significantly influenced by the prolonged cold storage. However, KCI-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.