Effect of clonidine on adrenal medulla catecholamine levels in rats.

The effects of clonidine on adrenal medulla catecholamines levels were studied in normotensive rats. Intraperitoneal injections (50,100 micrograms/kg) of clonidine caused a dose-dependent decrease in adrenaline content of the gland. This effect was suppressed by denervation of the adrenal medulla, i.e. unilateral section of splanchnic fibers performed 5 days before. These results demonstrate that clonidine decreases the catecholamine content of the adrenal medulla only through a central action. They suggest that the adrenal medulla is involved in the hypotensive effect of clonidine.