EFFECT OF RESINIFERATOXIN ON STIMULATED GASTRIC-ACID SECRETORY RESPONSES IN THE RAT

The effect of the capsaicin analogue 'resiniferatoxin' (RTX) was studi ed on basal and stimulated gastric acid secretory responses following sc bethanechol (1.5 mg/kg), sc pentagastrin (50 mu g/kg) and sc histam ine (0.5 and 2.5 mg/kg) in the I-h pylorus-ligated plus saline (2 mi i g)-treated rats. Resiniferatoxin applied intragastrically in doses of 0.6 and 1 mu g/kg at time of pylorus-ligation and administration of th e above secretagogues reduced acid secretory responses to bethanechol by 18.3 and 26.4%, to 0.5 mg/kg histamine by 39.9 and 44.6%, to 2.5 mg /kg histamine by 21.3 and 40.8% and to pentagastrin by 10.2 and 30.9% respectively. A single sc injection of 0.4 mu g/kg of RTX abolished ba sal secretion in pylorus ligated rats (which did not receive ig saline ). Our results indicate that locally applied RTX is capable of inhibit ing basal secretory responses and modifying gastric acid responses sti mulated with histamine, bethanechol or pentagastrin in the rat.