Blockade of vasopressor and vas deferens responses by α, β‐methylene ATP in the pithed rat

Abstract

1 The pressor responses produced by the intravenous administration of α,β-methylene ATP were tachyphylactic. 2 α,β-Methylene ATP can attenuate pressor responses to sympathetic nerve stimulation both in the presence and in the absence of α-adrenoceptor blocking agents. 3 α,β-Methylene ATP has no effect on the pressor responses produced by bolus injections of noradrenaline. 4 In the presence of α-adrenoceptor blocking agents, α,β-methylene ATP further attenuates contractions of the vas deferens produced by nerve stimulation. 5 The results, together with previous data, suggest that the vasopressor response to stimulation of the sympathetic outflow in the rat is partly purinergic and partly α-adrenergic and that this occurs as co-transmission. The same applies to rat vas deferens, confirming in vitro data. The pithed rabbit had an α-blocker-resistant vasopressor nerve-mediated response but this was resistant to α,β-methylene ATP.