[The endothelium--a microcosm of cardiovascular regulation].

Today, the endothelium can be considered a multifunctional "organ". In addition to its well-known role as a thrombophobic, semi-permeable barrier between the circulating blood and the extravascular space, it is now known to have major metabolic and synthesizing properties. In addition to prostacyclin, the endothelial cells also produce an endothelial relaxing factor (EDRF). These two substances bring about a dilatation of the smooth vascular muscles, and can inhibit platelet aggregation. The recently identified substance endothelin, which is also produced by the endothelium, appears to have mainly vasoconstrictive properties. In addition to an effect on endocrine parameters, e.g. enhanced liberation of vasopressin, aldosterone, atrial natriuretic peptide and renal parameters (reduced secretion of Na+) it is also reported to interact with prostacyclin and EDRF. Malfunctioning or injuries of the endothelium that, among other things, lead to a reduced synthesis of the relaxing substances or an increase in the production of endothelial vasoconstrictive substances, may have an influence on the pathogenesis of cardiovascular disease.