Circulatory and myocardial effects of endothelin.

The endothelin peptide family consists of the 21 amino acid isoforms endothelin-1, endothelin-2, endothelin-3, and sarafotoxin (a snake venom). Endothelin-1 has been isolated from the supernatant of endothelial cells and has subsequently been shown to be the most potent vasoconstrictor known to date and to be positively inotropic. This review summarizes some of the current literature pertaining to circulatory and myocardial effects of endothelins. Exogenously administered endothelin-1 has been demonstrated to increase peripheral resistance and blood pressure in a dose-dependent manner. However, during the first minutes of intravenous administration endothelins also decrease peripheral resistance and blood pressure, presumably due to the release of vasodilatory compounds such as nitric oxide, prostacyclin, and atrial natriuretic peptide. Endothelins appear to be involved in the pathogenesis of salt-dependent and renovascular animal models of experimental hypertension. Although endothelins appear to contribute to basal vascular tone, the role of endothelins in the pathophysiology of human hypertension remains unclear. In addition, a role has been suggested for endothelins in specific vascular lesions and inflammatory conditions (e.g., restenosis after coronary angioplasty, atherosclerotic coronary lesions, acute myocardial infarction, and vasculitis, glomerulonephritis). Endothelins are positively inotropic peptides in cardiac myocyte and papillary muscle preparations. They have also been demonstrated to induce hypertrophy of cardiac myocyte and may play an important role in ventricular processes that lead to chronic cardiac failure. The pathophysiological relevance of the endothelin system in human disease states is elucidated using selective (ET[A]) and nonselective (ET[A/B]) inhibitors of the endothelin receptors.