Apamin- and nitric oxide-sensitive biphasic non-adrenergic non-cholinergic inhibitory junction potentials in the rat anococcygeus muscle

Abstract

1. Changes in membrane potential following electrical field stimulation (EFS; 1, 2 and 5 pulses at 5 Hz, 0.5 ms duration, 60-80 V) of non-adrenergic non-cholinergic (NANC) inhibitory nerves in the rat isolated anococcygeus muscle were measured using standard intracellular recording techniques. Resting membrane potential ranged between -60 and -70 mV. 2. In the presence of guanethidine (30 μM), atropine (1 μM), propranolol (1 μM) and phentolamine (0.05 μM) to establish NANC conditions, the membrane potential depolarized to between -40 and -50 mV. Under these conditions, EFS caused pulse-dependent, tetrodotoxin (1 μM)-sensitive biphasic inhibitory junction potentials (IJPs) comprising a fast o..