Aldosterone and anti-aldosterone effects in cardiovascular diseases and diabetic nephropathy.

Cells in the cortical collecting duct of distal nephron have been considered for a long time as the unique cellular targets of aldosterone. However, it is now clear that other cell types in non-epithelial tissues are also potential targets for aldosterone. The functions that this hormone controls in non-epithelial tissues are still a matter of debate. Clinical and experimental studies have established that aldosterone plays a major role in the pathophysiology of cardiovascular and renal diseases. The aldosterone receptor antagonists spironolactone and eplerenone have demonstrated specific effects not related to their hypotensive properties in hypertension or cardiac diseases. It appears that a key action of these molecules is related to prevention or treatment of end-organ damage. The latter fact, and the recognition of aldosterone escape on long-term treatment of heart failure, diabetic nephropathy and some forms of hypertension with ACE inhibitors, justify the clinical use of aldosterone receptor antagonists provided that kaliemia is controlled. Experimental studies have allowed to draw a still incomplete but comprehensive scheme of aldosterone cardiovascular actions in pathological conditions. When elevated, aldosterone has deleterious effects in blood vessels, in the heart and in kidney, which are secondary to the induction of inflammatory and oxidative processes and necrosis, that induce the increased synthesis of extracellular matrix proteins.

Aldosterone-synthase overexpression in heart: a tool to explore aldosterone's effects.

Clinical observations indicate that elevated aldosterone impairs cardiovascular function. The mechanisms, however, are not totally understood although total and cardiovascular mortality are decreased by aldosterone antagonists. Experimentally, increased plasma aldosterone induces pericoronary inflammation and cardiac fibrosis. Our laboratory has discovered that aldosterone is synthesized in the rat heart, and has demonstrated that this cardiac aldosterone is involved in post-infarction cardiac remodeling. In man, activated cardiac aldosterone production has been described in patients with heart failure. In transgenic mice that overexpress aldosterone-synthase in the heart, we observe a normal cardiac function but a major coronary dysfunction, more pronounced in males. These observations converge to a potential physiological and pathological relevance of this system. Beneficial effects of anti-aldosterone treatment in heart failure may thus be secondary in part to blockade of cardiac aldosterone action.