An analysis of the postjunctional component of denervation supersensitivity in the isolated vas deferens of the guinea-pig.

An attempt was made to devise evidences for a role of calcium ions in the postjunctional component of denervation supersensitivity. The evidences obtained are: chronic postganglionic denervation increases sensitivity and maximum response of the vas deferens to cumulative concentrations of calcium and alters the pattern of response to low-calcium, potassium-rich Krebs solution; denervation supersensitivity could not be demonstrated after depolarization, and in KC1-Ringer or in Ca2+/--free Krebs solution the rate of loss of responsiveness to acetylcholine was delayed after denervation whereas the rate of loss of responsiveness to noradrenaline was unaffected. It is suggested that the postjunctional component of denervation supersensitivity in the isolated vas deferens of the guinea-pig is due, at least partially, to an increased availability of a membrane-bound calcium store(s) associated to an enhanced cell membrane permeability to the ion.