Abstract
The influence of vasopressin on the adrenal catecholamine secretion was investigated in rats. Neither a single intraperitoneal injection of 1 U vasopressin per 100g body weight nor repeated injections of 0.4-0.8 U vasopressin per 100g body weight by 10 times resulted significant change in the catecholamine content in the adrenal gland. 1.5mg of acetylcholine per 100g body weight failed to produce any significant change in the adrenal catecholamine content. Combined administration of acetylcholine with vasopressin showed no effect either.
The adrenaline content of the adrenal venous blood collected for a 10-minute period significantly rose during vasopressin infusion in dose of 100 mU or 500 mU in 5 out of 11 experiments, while no change in noradrenaline was observed. 2U vasopressin, however, seemed to possess a suppressive effect on the catecholamine secretion. 500 mU of vasopressin simultaneously administered with acetylcholine augmented the latter's action to increase the adrenaline output, but not noradrenaline. Since the extent of this augmentative effect far exceeded that accounted for by a simple additive effect, vasopressin was considered to potentiate the action of acetylcholine to stimulate the adrenaline secretion from the adrenal medulla.
