α2-Adrenoceptor-mediated autoinhibition of sympathetic transmitter release in guinea-pig vas deferens studied by intracellular and focal extracellular recording of junction potentials and currents

Abstract

Excitatory junction potentials (e j.ps; intracellular electrodes) and excitatory junction currents (e.j.cs; extracellular electrodes) elicited by stimulation (20 pulses at 1 Hz every minute) of the hypogastric nerve trunk were recorded from guinea-pig isolated vas deferens. Intracellular recording. At a variety of stimulation intensities, bath-applied yohimbine (0.1-1 μmol/l) did not change the first one to three e j.ps in a train but increased the amplitude of subsequent e j.ps. The effect of yohimbine was abolished in tissues from reserpinepretreated guinea pigs. Bath-applied desipramine (0.1 μmol/l) diminished the amplitude of all but the first one to three e j.ps in a train. - Extracellu..