Studies on the renin response to vasoactive intestinal polypeptide (VIP) in the conscious rabbit

Vasoactive intestinal polypeptide (VIP) has been found within the renal cortex and is believed to be a neurotransmitter. Although it produces systemic vasodilatation and renin release, the exact mechanism of the latter response is uncertain. When infused into conscious rabbits, VIP elicits a rise in plasma renin activity (PRA) and an increase in heart rate. The rise in PRA is unaltered by pretreatment with propranolol, but is attenuated by indomethacin. The tachycardia is inhibited by propranolol, but unaffected by indomethacin. We conclude that the renin response to VIP is in part prostaglandin-dependent and that the heart rate response is due to direct or reflex beta-adrenoceptor stimulation.