The Effect of Isoprenaline on the Blood Flow Through Individual Skeletal Muscles in The Anaesthetised Cat

Abstract The effects of intra-arterially and intravenously administered isoprenaline on the venous outflow from individual skeletal muscles in the hind limbs of cats under chloralose anaesthesia were studied. By intraarterial injection isoprenaline was more powerful in causing vasodilatation than adrenaline. The dilator response to intravenously administered isoprenaline was shown by cross-circulation techniques and by the use of a blood pressure stabiliser, to be reflexly inhibited by a vasoconstriction initiated by the fall in blood pressure. In the innervated muscle when vasomotor tone was high, intravenously administered adrenaline was more potent than isoprenaline in producing vasodilatation. The reverse was true in the acutely denervated muscle. The dilator response to isoprenaline was shown to be the result of a direct action on the muscle blood vessels; no evidence was obtained of a reflex dilatation, such as has been demonstrated with adrenaline and noradrenaline.