The role of vagal adrenergic activity in the mechanism of gastric acid secretion after pylorus-ligation in the rat.

The role of the vagus nerve and adrenoceptor stimulation in acid secretion after pylorus-ligation in the rat has been examined. All drugs were administered intraperitoneally. Atropine (5 mg kg-1) depressed the H+ output (111 mumols +/- 33.8 vs 412.5 mumols +/- 62.2, mean +/- s.e.m., n = 10, P less than 0.001); cimetidine (40 mg kg-1) did not enhance this action, while vagotomy was more effective than atropine (32.7 mumols +/- 4.9, mean +/- s.e.m., n = 10, P less than 0.05). Atropine (10 mg kg-1) produced a similar depression to the 5 mg kg-1 dose. Cimetidine (100 mg kg-1) depressed the H+ output (248.5 mumols +/- 46.8, mean +/- s.e.m., n = 10, P less than 0.05). Propranolol (5-20 mg kg-1) had no significant effect on the H+ output but dose-dependent inhibition was produced by phenoxybenzamine or phentolamine; an inhibition similar to that achieved by vagotomy was seen with the 20 mg kg-1 dose. Both these drugs (5 or 10 mg kg-1) had no significant effect on the H+ output when given with atropine (5 mg kg-1) but the H+ output was significantly lower than that produced by either drug at the same dose given alone. Atropine (5 mg kg-1) with phenoxybenzamine or phentolamine (20 mg kg-1) produced H+ output not significantly different from that with vagotomy or either alpha-adrenoceptor given alone at 20 mg kg-1, but the result was significantly (P less than 0.05) lower than the H+ output with atropine (5 mg kg-1) alone.(ABSTRACT TRUNCATED AT 250 WORDS)