Peripheral Vascular Effects of Mixtures of Isopropylnoradrenaline and Noradrenaline in Man

Abstract

IT is well known that the infusion of 0.1–1.0 µg/min adrenaline into the brachial artery in man results in an immediate transient increase in flow of blood in the forearm followed by a fall to below the resting level. Allen, Barcroft and Edholm¹ showed that this biphasic response was not due to dilatation of muscle vessels followed by constriction of skin vessels. Finding that after dibenyline, adrenaline produces only a sustained vasodilatation, Ginsburg and Cobbold² suggested that the action of adrenaline when given alone was due to an initial stimulation of inhibitory (β) receptors followed by stronger stimulation of excitatory (α) receptors. The action of adrenaline after dibenyline resembles that of iso-propylnoradrenaline. Recently we have found that after dichloroisopropylnoradrenaline, adrenaline causes only sustained vasoconstriction. and under these conditions resembles noradrenaline³.