Plasma shedding by the canine oxyntic and pyloric glandular mucosa induced by topical action of acetylcholine. Effect of atropine and physostigmine.

Irrigation of the canine oxyntic or pyloric glandular mucosa in vagally denervated pouches with a solution of acetylcholine causes the mucosa to shed plasma proteins and the potential difference across the mucosa to fall. The response is dose-related with the threshold concentration of acetylcholine bromide ranging from 0.1 to 1 g per 100 ml. Topical application or intravenous injection of atropine prevents both plasma shedding and decline in potential difference. The minimal effective intravenous dose of atropine sulfate is about 0.007 mg per kg. The effect of irrigation with low concentrations of acetylcholine is enchanced by concurrent irrigation with physotigmine. The action of topical acetylcholine is not affected by concurrent irrigation with hexamethonium chloride (0.5 g per 100 ml) or by intravenous injection (5 mg per kg). Topical application of gallamine triethiodide (0.5 g per 100 ml) or d-tubocurarine (0.15 g per 100 ml) does not prevent the effects of acetylcholine in causing plasma shedding. Topical application of succinylcholine chloride (1 g per 100 ml) does not cause plasma shedding or a fall in potential difference.