THE EFFECTS OF ATROPINE AND OXOTREMORINE ON ACETYLCHOLINE RELEASE IN RAT PHRENIC NERVE‐DIAPHRAGM PREPARATIONS

Abstract

1 Atropine (10⁻⁵m) enhanced the release of [³H]-acetylcholine from rat isolated hemidiaphragms, previously incubated with [³H-methyl]-choline, stimulated via their phrenic nerves. 2 Oxotremorine (10⁻⁵m) did not affect the stimulated release of [³H]-acetylcholine but antagonized the facilitatory effects of atropine (10⁻⁵m). 3 It is suggested that there are presynaptic inhibitory muscarinic receptors that modulate the release of acetylcholine in the phrenic nerves of the rat.