The effect of guanethidine on the noradrenaline content of the adult rat superior cervical ganglion.

: The administration of guanethidine sulphate in doses above 10 mg/kg intraperitoneally for more than a week induced a considerable reduction (up to 80 %) of the noradrenaline content in the adult rat superior cervical ganglion. With 5 mg/kg no changes were observed, even after administration for 4 weeks. Single injections of 5 and 20 mg/kg had no effect on the ganglionic noradrenaline. Following administration for 14 days in a dose of 20 mg/kg, normalization of the ganglionic noradrenaline was complete within 8 days. Following 40 mg/kg For 18 days recovery was only partial - probably due to irreversible degeneration of some ganglion cells. The effect of guanethidine on the noradrenaline content in the superior cervical ganglion is different from its noradrenaline depleting effect in sympathetically innervated peripheral organs and is assumed to be secondary to chromatolytic changes in the ganglionic nerve cells induced by guanethidine, some of these changes being irreversible following high doses for long periods of administration.