Abstract
Studies were performed on the nature of splanchnic-adrenal transmission in the rat. Marked adrenaline secretion was observed after electrical stimulation of the greater splanchnic nerve, and optimum voltage and frequency in a train of tetanus of 1 mscc square for 10 sec at 10 sec intervals were 5 V and 20 c/sec respectively. Hexamethonium bromide caused marked inhibition of the response to the nerve stimulation and at a dose of 1 mg/kg, the inhibition rate was about 75%. Atropine also prevented adrenaline secretion in response to the tetanus, but the inhibitory action of 5 mg/kg of atropine sulfate was equipment to that of only 0.2 mg/kg of hexametlion ium bromide. Five mg/kg of atropine sulfate after i.v. Injection of 1 mg/kg of hexamethonium bromide caused appreciable inhibition of the residual adrenaline release by the stimulation of splanchnic nerve. It is concluded that transmission of impulses through muscarinic receptors may occur in the adrenal medulla of the rat, though this type of transmission is less prominent than that through nicotinic receptors.
