Cardiovascular interactions of nonivamide, glyceryl nonivamide, capsaicin analogues, and substance P antagonist in rats.

Nonanoyl vanillylamide-4-o-glycerol (glyceryl nonivamide, GLNVA) a nonpungent ether-linked derivative of nonanoyl vanillylamide (nonivamide, NVA) was compared to capsaicin (CAP) and NVA with regard to its depressor response in rats. IV injection of CAP and NVA (10(-1) to 10(-4) mg/kg) in Wistar rats elicit a triphasic blood pressure response, bradycardia, and aponea. However, IV injection of GLNVA results in a monophasic reduction in blood pressure, with little effect on heart rate and respiration. The depressor response to GLNVA was not diminished by bilateral vagotomy or by systemic pretreatment with atropine. Following the CAP pretreatment, the delayed hypotension induced by CAP, NVA, and the hypotension of GLNVA was almost abolished. Injection of CAP, NVA (10 micrograms/kg), or GLNVA (100 micrograms/kg) into one femoral artery elicited a fall in blood pressure in the rat. This effect was abolished following intrathecal injection of substance P antagonist [D-Pro2,D-Trp7,9]-SP. Microejections of CAP, NVA, or GLNVA into the nucleus tractus solitarii (NTS) evoked hypotension, the bradycardia following microejection of CAP and NVA into the NTS occurred only at higher doses of GLNVA. From these results it is suggested that GLNVA appears to act more exclusively than CAP by stimulating peripheral perivascular small diameter C-fiber sensory nerves.