INHIBITION OF PURINERGIC TRANSMISSION BY PROSTAGLANDIN E(1) AND E(2) IN THE GUINEA-PIG VAS-DEFERENS - AN ELECTROPHYSIOLOGICAL STUDY

1 The effects of prostaglandin E(1) (PGE(1)) and E(1) (PGE(2)) On post junctional electrical activity in the guinea-pig vas deferens evoked b y sympathetic nerve stimulation were investigated using both intracell ular and focal extracellular recording techniques in vitro. 2 Bath app lication of PGE(1) (1-100 nM) or PGE(2) (0.1-100 nM) concentration-dep endently inhibited the amplitudes of an excitatory junction potentials (e.j.ps) evoked during short trains of stimuli (10 stimuli at 1 Hz). Increasing the duration of nerve stimulation (100 stimuli at 1 Hz) did not overcome this inhibitory effect. At these concentrations PGE(1) a nd PGE(2) were without any apparent inhibitory effect on the amplitude s of spontaneous e.j.ps. 3 Local application of PGE(1) (10-100 nM) of PGE(2) (10-30 nM) markedly reduced the frequency of occurrence of exci tatory junction currents (e.j.cs) evoked by trains of 20-100 stimuli a t 1 to 4 Hz without changing the amplitudes of spontaneous e.j.cs or t he configuration of the nerve terminal impulse. 4 In the presence of P GE(1) or PGE(2), raising the frequency of stimulation (from 1 to 4 Hz) , increased the likelihood of e.j.c. occurrence. 5 The postjunctional electrical activity recorded in the guinea-pig vas deferens is believe d to be due to ATP released from the sympathetic nerve endings. Thus t he present study demonstrates that both PGE(1) and PGE(2) powerfully i nhibit quantal ATP release in the guinea-pig vas deferens.