THE RESPONSE OF THE DENERVATED NICTITATING MEMBRANE AND OF BLOOD PRESSURE TO SYMPATHETIC NERVE STIMULATION IN ADRENALECTOMIZED CATS

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Abstract
In order to determine whether exhaustion of sympathin at adrenergic nerve endings could account for the failure of sympathetic nerve stimulation to cause any substantial rise in blood (in adrenal insufficiency) pressure the liberation of sympathin was studied in adrenalectomized cats. The responses of the blood pressure and of the denervated nictitating membrane (n.m.) were used as criteria in animals anesthetized with urethane. The responses to splanchnic nerve stimulation in adrenalectomized cats maintained 21-41 days by cortin were normal compared with acutely adrenalectomized controls. Cats off cortin 9 or 10 days and in mild or moderately severe adrenal insufficiency showed a normal pressor but impaired n.m. response. Consideration of the altered circulatory conditions in adrenal insufficiency indicates that the impaired n.m. response is dependent on this rather than on decrease in the amt. of sympathin liberated. In animals in which the blood pressure was below 40 mm Hg. little pressor and no n.m. effect was observed. Exhaustion of sympathin in the splanchnic region is evidently not the cause of the vascular failure in adrenal insufficiency. Cardiac malfunction is possibly the important factor.