Changes in hormonal activities relative to the severity of essential hypertension

Endocrine activity in patients with essential hypertension was studied by measuring the urinary excretion of catecholamines, prostaglandin E (PGE) and cyclic adenosine monophosphate (cAMP). Simultaneously, plasma renin activity, concentrations of serum sodium, potassium, blood urea nitrogen (BUN) and creatinine were determined. Systolic blood pressure and BUN increased progressively with age until the sixth decade. Urinary excretion of norepinephrine was correlated with the systolic blood pressure. In contrast, plasma renin activity and urinary excretion of PGE decreased progressively with the increase in systolic blood pressure. Although the cause of essential hypertension is not known, it is suggested that hypertension accelerates the aging process in the kidney and thus decreases renal PGE synthesis. This decrease of PGE in turn causes a reduction of plasma renin activity, possibly either by accelerating the retention of sodium and water or by failing to stimulate renin synthesis. A decrease of PGE may also potentiate the vasopressor action of norepinephrine.