EXCRETION OF EPINEPHRINE AND NOREPINEPHRINE AFTER ADMINISTRATION OF INSULIN AND METHACHOLINE*

Abstract

Using insulin as the hypoglycemic agent and methacholine as the hypotensive drug, a study was conducted to evaluate the sympath-ico-adrenal response of 10 normal male subjects by measur-ing the blood pressure (BP), pulse, and the excretion of epineph-rine (E) and norepinephrine (NE). The N and NE infusion experiments were conducted with graded dosages of 0.05, 0.10, and 0.20 [mu]g/kg/minutes for 30 minutes; control experiments were carried out with physiologic saline. BP, pulse rate, and excretions of E and NE were determined. Results of these ex-periments were used to evaluate the nature and quantity of E and NE secreted after administration of insulin and methacholine. Administration of insulin (0.1 unit/kg) resulted in elevation of systolic BP, slight decrease in diastolic pressure, tachycardia, and marked increase in the excretion of E. These findings simulated the effects of E infusion in all respects. The esti-mated secretion of E as a result of hypoglycemia was in the order of 0.15 [mu]g/kg/minute. Methacholine given intramuscularly in a 10-mg dose induced a slight increase in the NE excretion, when compared with insulin, but there was no appreciable change in E excretion. The tachycardia observed was presumed to be due to cardioaccelerator stimulation via the sino-aortic reflex (neurogenic), rather than to an increased adrenal medullary secretion of E as is the case after insulin. The increase in NE was slight and of an order no greater than 0.05 [mu]g/kg/minute. When high BP and pulse readings were observed in the premedi-cation period, the excretions of E and NE were elevated.