NO-RELATED CARDIOVASCULAR-DISEASES

Alterations of the endothelium: Because of its anatomic position betwe en circulating blood and smooth muscle cells, the vascular endothelium is a prime target for cardiovascular diseases such as hypertension, h ypercholesterolemia, diabetes or ischemia, The morphological changes o ccurring in the endothelium have been known for many years, but is was only recently that the functional alte rations have been described. I mpact of NO: Under physiological conditions, the vascular endothelium plays a protective role by secreting relaxation factors. In the diseas e state, the synthesis and release of NO may be reduced or even abolis hed. The exact significance of endothelium-dependent vasodilatation di sorders remains a topic of research, but the properties of NO strongly suggest it is involved in several diseases. For some diseases it is s till a question as to whether the observed anomalies are the cause or the consequence oi the underlying disease. Disease-specific changes: N O is known to be reduced in atherosclerosis, either because of less sy nthesis or accelerated degradation, in different experimental models o f hypertension the baseline level oi NO release appears to be decrease d. Conversely, NO release can be normal, reduced or increased in diabe tes. In heart failure, there appears to be not only a permanent altera tion in NO secretion, but also an increase in factors stimulating vasc ular contraction, contributing to an altered capacity for vascular ada ptation in these patients. (C) 1998, Masson, Paris.