Bretylium and the supersensitivity to exogenous noradrenaline after sympathetic denervation studied in the conscious rat.

Abstract

AbstractRats denervated by excision of the superior cervical sympathetic ganglion and given reserpine at the time of operation were used. The width of the palpebral aperture, which reflects the tone of the sympathetically innervated periorbital smooth muscle, was measured in the conscious rats after different i.p. doses of 1‐noradrenaline. The sensitivity of the muscle to exogenous noradrenaline was thus tested during 3 periods of 3 h duration each between 13 and 30 h after denervation. Bretylium, which is known to delay the degeneration contraction of the muscle, i.e. the degeneration transmitter release, postponed the development of denervation supersensitivity. Hence, bretylium seems to preserve temporarily both the amine storage mechanisms and the axonal amine pump in the degenerating adrenergic nerve terminals.