Comparison of the purinergic contribution to sympathetic vascular responses in SHR and WKY rats in vitro and in vivo

Abstract

Isolated tail arteries from spontaneously hypertensive rats (SHR) were more responsive than those from Wistar-Kyoto (WKY) control rats to exogenously applied noradrenaline (NA), ATP, α,ß-methylene ATP (mATP), KCl and sympathetic nerve stimulation. The sympathetic contractile responses of the SHR and WKY were both reduced to 10–20% of control by α 1-adrenoceptor antagonism. The pressor responses to sympathetic nerve stimulation were significantly greater in the SHR than the WKY rats at all stimulation frequencies examined (1–10 Hz). There was no significant difference between SHR and WKY rats in the magnitude of pressor responses produced by i.v. administration of NA or mATP. The pressor responses to sympathetic nerve stimulation in the pithed SHR were no more resistant to α-adrenoceptor antagonism than those of the WKY. The results suggest that the contribution by ATP to sympathetic vasconstriction is no greater in SHR than WKY.