Effect of metoprolol on 24‐hour urinary excretion of adrenal steroids and kallikrein in patients with essential hypertension

1 Treatment of fifteen patients with essential hypertension over four weeks using the β-adrenoceptor blocking agent, metoprolol, resulted in a decrease in 24 h urinary excretion of kallikrein and aldosterone along with a decrease in plasma renin activity. 2 There was no significant change in 24 h excretion rates of the free adrenal steroids deoxycorticosterone, 18-OH-deoxycorticosterone, corticosterone, cortisol or 18-OH-corticosterone during treatment, which were not significantly different from excretion rates of normal males, thus excluding inhibitory effects of adrenal steroids on urinary kallikrein activity. 3 A positive correlation was found between plasma renin activity and urinary excretion of kallikrein during the control period and after 2 weeks on metoprolol, supporting the assumption of a preserved link between the renin-angiotensin-aldosterone system and the renal excretion of kallikrein in these patients. 4 The decrease in kallikrein excretion during β1-adrenoceptor blockade in patients with essential hypertension may be explained by a reduction in sympathetic tone and by reduced activity of the renin-aldosterone system.