Hypertension and the microcirculation

A large part of the changes in peripheral resistances associated with hypertension involves changes in the microvascular network. From the brief review presented here, it appears that arterioles' functional characteristics are largely modified in hypertension. Sensitivity to numerous vasoconstrictive substances is increased. Local angiotensin-converting enzyme activity is considerably higher. Endothelium-dependent dilation is reduced. Myogenic responses are also amplified by mechanisms dependent on both prostanoids and endothelin. Oxidative stress has been recently demonstrated to be an important pathophysiological mechanism of these alterations. Changes also affect the structure of the microvascular network. Morphological alterations in the arteriolar wall are not observed for all types of hypertension. Conversely, arteriolar and capillary rarefaction appears to be the changes affecting the structure of the microvascular network which are most often found. This led us to consider that the microvascular network should not only be considered as one of the putative mechanisms responsible for increased blood pressure but also as a key target for hypertension. Consequently, hypotensive drugs should also be tested and differentiated as regards their efficiency to prevent or to reverse the microcirculatory damage associated with hypertension.