Responsiveness of skeletal muscle branches of the dog femoral artery to alpha-adrenoceptor agonists before and after cold storage.

Using the cannula inserting method, we investigated the responsiveness of isolated skeletal muscle branches of the dog femoral artery to alpha-adrenoceptor agonists and potassium chloride, and the influence of cold storage (3 days and 5-7 days, at 4 degrees C). Epinephrine (EPI) and norepinephrine (NE) induced a marked vasoconstriction in a dose-related manner. A large dose of EPI and NE usually induced an increase in perfusion pressure of more than 100-200 mm Hg. Phenylephrine (PE) and methoxamine (MT) also induced a marked constriction, but clonidine (CLO) and xylazine (XYL) produced only a slight vasoconstriction, even in large doses. Tyramine (TYR) also induced a small vasoconstrictor response. A large dose of KCl induced a marked vasoconstriction. The order of potency of constriction was EPI greater than or equal to NE greater than PE = MT much greater than KCl greater than CLO greater than or equal to TYR greater than or equal to XYL. The vasoconstrictor responses to EPI and NE were significantly suppressed by 3-7 days of cold storage. Vasoconstrictor responses to MT were slightly suppressed by cold storage. However, XYL-, CLO- and TYR-induced vasoconstrictions were not significantly influenced by cold storage. KCl-induced constriction was clearly suppressed by cold storage. These observations suggest that the postjunctional alpha-adrenoceptor in skeletal muscle branches of the femoral artery is of the alpha 1-type. Moreover, it was shown that prolonged cold storage (3-7 days, at 4 degrees C) resulted in a decrease in sensitivity of these vessels to alpha-adrenoceptor agonists and in a marked decrease in sensitivity to KCl, suggesting a depression of the calcium channel by cold storage.