Relationship between plasma catecholamines, plasma renin activity, aldosterone, and arterial pressure during postural stress in normal subjects.

The relationship between plasma catecholamines, PRA, aldosterone, and MBP in the supine and upright positions and after furosemide were studied in 44 normal subjects. Supine plasma NE correlated with MBP (r = 0.52, p greater than 0.01) and with age (r = 0.57, p greater than 0.01). The partial correlation coefficient of plasma NE with MBP controlling for age was r = 0.40, p greater than 0.025. These data suggest that the sympathetic nervous system plays an important role in the maintenance of blood pressure during the supine position. With upright posture, plasma NE and E, PRA, and plasma aldosterone increased significantly, whereas urinary sodium excretion decreased and urinary excretion of NE did not change.