Mechanical responses of rat isolated uterine horns to transmural stimulation

1 Transmural stimulation of rat isolated uterine horns at low pulse width produced contractions. These were antagonized by hyoscine or tetrodotoxin and potentiated by physostigmine. 2 In the presence of hyoscine, and during bradykinin-induced contractions, transmural stimulation produced inhibition. This inhibition was antagonized by guanethidine, propranolol or tetrodotoxin. 3 Hexamethonium or pempidine did not affect responses to transmural stimulation. 4 It is suggested that transmural stimulation is a method of exciting cholinergic motor and noradrenergic inhibitory postganglionic neurones to the rat myometrium.