Central modulation of gastric pressure by substance P: a comparison with glutamate and acetylcholine.

We have sought to determine if changes in arterial and gastric pressure occurred with selective chemical stimulation of the dorsomedial NTS. Substance P (SP) and L-glutamate (L-glu), but not acetylcholine (ACh), elicited a dose-dependent decrease in tonic gastric pressure and inhibited gastric phasic activity. As previously reported, L-glu and ACh, but not SP elicited dose-dependent arterial hypotension. The data support a putative role for SP in visceral reflexes mediated by vagal nerves.