The most important hormone regulators of electrolyte reabsorption and secretion are the angiotensin II and aldosterone. Aldosterone is a mineralocorticoid hormone that is secreted by the adrenal cortex and regulates the balance of sodium and potassium in the body, while Angiotensin is any of several polypeptides that narrow the blood vessels and regulate arterial pressure. Angiotensin II causes vasoconstriction and an increase in systemic blood pressure.