Effect of iontophoretic application of cholinergic agonists and their antagonists to guinea‐pig pelvic ganglia

Abstract

1 The electrical activity of guinea-pig pelvic ganglion cells following iontophoretically applied cholinergic drugs, alone and during orthodromic nerve stimulation via the hypogastric nerve, has been recorded intracellularly. 2 Iontophoretic application of nicotine (Nic) and acetylcholine (ACh) reduced membrane resistance and caused a depolarization which in approximately 80% of cells led to the firing of action potentials. In the remainder, depolarization was unaccompanied by firing. 3 Iontophoretic application of Nic and ACh reduced or abolished the amplitude of successively evoked orthodromic responses. 4 ACh-induced depolarization, unlike that caused by tetanic stimulation, was not followed by a subsequent increase in the frequency of synaptic potentials. 5 Di-hydroβerythroidine (DHβE) and atropine (Atr) inhibited the response to both orthodromic stimulation and iontophoretic application of Nic and ACh. 6 There was no evidence for the existence of muscarinic receptors in guinea-pig pelvic ganglia. Iontophoretic application of muscarinic agonists alone and after tetanic stimulation of the hypogastric nerve produced no significant depolarization of the ganglion cell membrane.