Urinary catecholamine response to glucagon in young and elderly patients with essential hypertension

The role of the sympathetic nervous system (SNS) in essential hypertension was evaluated by examining the response of urinary catecholamines to the intramuscular injection of glucagon in both young and elderly normal subjects (total 16) and in both young and elderly patients with essential hypertension (total 16). Urine was collected for 2 hours before glucagon injection and for 2 and 4 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 than in young normotensive subjects or in normotensive and hypertensive elderly subjects. The observation that the reactivity of the SNS is increased in young patients with essential hypertension lends support to the hypothesis that the SNS is more important in the maintenance of hypertension in the young than in the elderly.