Cell biology of vascular hypertrophy in systemic hypertension.

Recent data demonstrate that in addition to its conduit function, the blood vessel is an active synthetic and secretory organ containing several autocrine and paracrine systems that are involved with the local regulation of its own function (i.e., structure and growth). The endothelium secretes vasorelaxant and vasoconstrictive substances, growth factors and inflammatory mediators that exert paracrine influences on vascular myocyte function. The vascular myocyte also expresses autocrine substances that influence its own function. The autocrine systems include angiotensin, prostaglandins, platelet-derived growth factor, insulin-like growth factor and heparin. These local factors exert modulatory influences on myocyte contractility and growth. These autocrine and paracrine systems serve as an adaptive mechanism by which the vasculature autoregulates its structural and functional state. We speculate that an alteration in this delicate balance of these local factors, due to genetic or acquired abnormalities, can result in increased vascular tone and vessel hypertrophy and thereby contribute to the pathogenesis of hypertension.