An electrophysiological study of excitatory neuromuscular transmission in the guinea‐pig main pulmonary artery.

Abstract

Electrical responses of single smooth muscle cells to perivascular nerve stimulation were recorded in the guinea-pig main pulmonary artery with a micro-electrode, to investigate neuromuscular transmission mechanisms. Perivascular nerve stimulation produced excitatory junction potentials in the smooth muscle cells of the main pulmonary artery. When stimulation was repetitive and of high frequency, a spike was seen in the early part of these potentials. Phentolamine, prazosin, phenoxybenzamine, guanethidine or tetrodotoxin all suppressed first the pike and then the junction potential. Exogenously applied noradrenaline [norepinephrine] also produced depolarization, and in high concentrations above 10-6 M, spikes. Phentolamine again suppressed the spikes and then the depolarization. Apparently, endogenous and exogenous noradrenaline act on the same type of receptor in this artery.