Urinary Catecholamine Response to Glucagon in Young and Elderly Patients with Essential Hypertension

Abstract

The role of the sympathetic nervous system in essential hypertension was evaluated by examining the response of urinary catecholamines to intramuscular injection of glucagon in both young and elderly normal subjects and in patients with essential hypertension. Urine was collected for two hours before glucagon injection and two and four hours after injection for determination of adrenaline and noradrenaline. The increments of urinary adrenaline and noradrenaline after glucagon injection were significantly higher in young hypertensive subjects than in young normotensive or in normotensive and hypertensive elderly subjects. But, there were not any significant differences in urinary catecholamine responses between in young and elderly normotensive subjects, also between in hypertensive and normotensive elderly subjects. Our observation that the reactivity of the sympathetic nervous system is increased in young patients with essential hypertension lends support to the hypothesis that the sympathetic nervous system is more important in the maintenance of hypertension in young individuals with essential hypertension than in elderly hypertensives. Whereas, we could not find out an overreactivity of sympathetic nervous system in elderly essential hypertension and the alteration of sympathetic nervous response due to ageing in normotensive subjects.