Essential hypertension: relationship between renin and blood pressure

Supine (basal) plasma renin activity (PRA) and mean arterial pressure (MAP) were determined in 564 essential hypertensives grouped by age and sex. Mean supine PRA showed an age-dependent significant decrease (p < 0.001), whereas an increase in MAP was observed with age (p < 0.001). There were no sex-related differences both in PRA and MAP. In younger hypertensives (15-34 years) of both sexes an inverse correlation was obtained between PRA and MAP, whereas middle-aged men (35-50 years) and male and female hypertensives of older age (> 51 years) showed a positive relationship between these two parameters. No significant correlation was seen between PRA and MAP in middle aged women (35-50 years). The observed findings suggest a negative feed-back mechanism between blood pressure and renin release in younger hypertensives. In older patients this mechanism is disturbed probably through hypertension induced changes in the renovascular system resulting in an inappropriate large release of renin for a given level of blood pressure. This conversion from an inverse to a positive relationship between PRA and MAP occurred earlier in male than in female patients. Finally, our results support the assumption that in essential hypertension changes in renin secretion are rather the sequel than the cause of elevated blood pressure.