Aldosterone and aldosterone antagonism in systemic hypertension.

Aldosterone mediates both water and electrolyte balance by acting on the renal mineralocorticoid receptors. Recent experimental studies have also documented the presence of these receptors in other body organs, including the brain, blood vessels, and heart, suggesting that aldosterone plays a larger role in normal physiologic function and in cardiovascular diseases such as systemic hypertension and congestive heart failure (CHF). The nonspecific aldosterone inhibitor spironolactone, and the selective aldosterone inhibitor eplerenone, are both approved for clinical use in treating patients with hypertension and/or symptomatic CHF. Studies have shown that spironolactone lowers blood pressure, improves endothelial function, reduces myocardial hypertrophy and fibrosis, and lowers the incidence of fatal arrhythmias. Eplerenone, which is more specific for the mineralocorticoid receptor, appears to provide all the beneficial effects of spironolactone in hypertensive patients, with the potential to modify many of the side effects related to nonspecific steroid-receptor blockade. Hyperkalemia remains a potential problem with all aldosterone antagonists.