Effects of l-Epinephrine and l-Norepinephrine on Foot Vasculature After Sympathectomy in Dogs

The acutely sympathectomized foot of dogs was less responsive to intra-arterially infused l-epinephrine and l-norepinephrine than the opposite control leg, as indicated by blood flow in the saphenous veins. In chronically sympathectomized legs, blood flow methods failed to disclose any increased sensitivity to intra-arterially or or intravenously infused epinephrine and norepinephrine. The degree of vasoconstriction induced by the two drugs was about equal, as was the rise in mean blood pressure. Blood vessel strips removed from the operated and control legs and tested in vitro responded differently to epinephrine and norepinephrine in that chronically sympathectomized vessels were twice as responsive to the two amines as were the controls. Chronic lumbar sympathectomy undoubtedly produced sensitivity changes in the leg vasculature, and while this was not demonstrable in the intact preparation it could be shown by in vitro studies.