Volume hormones and blood pressure.

Four major volume hormones may be involved in human hypertension: aldosterone, arginine vasopressin, inhibitors of NA+/K+ ATPase activity, and the natriuretic factor from specific granules of atrial cardiocytes. Because there is no increase in either blood or extracellular fluid volumes, or total exchangeable sodium in patients with mild essential hypertension, the mechanism of action of the volume hormones must be through their effect on sodium regulation, intracellular concentration, and the related enhancement of arteriolar sensitivity and responsiveness. A review of the evidence relating these hormones to blood pressure regulation emphasizes inhibitors of Na+/K+ ATPase activity, and the potent natriuretic and diuretic factor found in homogenates of rat atria.