PATHOGENETIC FACTORS IN HYPERTENSION ENDOTHELIAL FACTORS

In normotensive humans, endothelium modulates vascular tone mainly by the production of nitric oxide. In human essential hypertension the ba sal release of nitric oxide is reduced and forearm vasodilation to the endothelium-dependent agonists acetylcholine or bradykinin is blunted . Defective basal release of nitric oxide seems to be secondary to blo od pressure increase while impaired agonist-evoked endothelium-depende nt vasodilation is probably a primary phenomenum. This latter endothel ial dysfunction seems to be caused by the simultaneous presence of an alteration in the L-arginine-nitric oxide pathway and the production o f constrictor prostanoids. Defective nitric oxide production is alread y detectable in normotensive offspring of hypertensive patients and yo ung essential hypertensives. In contrast, vasoconstrictor prostanoid p roduction seems to be associated with aging. In essential hypertensive patients, although only scanty data are available, chronic effective pharmacological treatment seems to restore impaired basal production o f nitric oxide but does not improve vascular response to endothelial a gonists.