Immunohistochemical evaluation of microvascular rarefaction in hypertensive humans and in spontaneously hypertensive rats

No data are presently available about changes in capillary density in the skeletal muscle and in the brain of spontaneously hypertensive rats (SHR) in relation to the development of hypertension.We have investigated 4 week-old and 12 week-old SHR and age-matched normotensive Wistar-Kyoto controls (WKY). Microvessel density (MVD) in the cerebral cortex and in a skeletal muscle were evaluated in sections stained for CD31. We also evaluated MVD in the dermal tissue of normotensive subjects and essential hypertensive patients. Subcutaneous small resistance arteries were dissected and mounted in a micromyograph and the media to lumen ratio (M/L) was measured.A significant reduction in MVD in the skeletal muscle and in the brain of SHR was clearly observed at 12 weeks of age, after the development of hypertension, but not at 4 weeks of age (pre-hypertensive condition). In hypertensive patients a significant reduction in the dermal MVD and an inverse correlation between M/L and MVD was observed.Our results suggest that, in the brain and skeletal muscle of adult SHR after the development of hypertension, and in the derma of adult essential hypertensive patients microvascular rarefaction may occur.