Structural alterations of small-resistance arteries may predict FCE and SMI. The prognostic role of small-resistance artery structure also applies to medium-risk patients with essential hypertension, at least when MCEs are included in the analysis.

Our results indicate that, in small resistance arteries of patients with primary aldosteronism, a pronounced fibrosis may be detected, even more evident than in blood-pressure-matched patients with essential hypertension.

Our results indicate that structural alterations of small cerebral vessels are present in hypertensive patients compared with normotensive individuals, similar to those previously observed in subcutaneous small arteries.

Structural alterations of subcutaneous small resistance arteries are associated with a worse clinical prognosis in hypertension and noninsulin-dependent diabetes mellitus (NIDDM). However, no data are presently available about the effects of antihypertensive therapy on vascular structure in hypertensive patients with NIDDM. Therefore, we have investigated the effect of an angiotensin-converting enzyme inhibitor, enalapril, and a highly selective angiotensin receptor blocker, candesartan cilexetil, on indices of subcutaneous small resistance artery structure in 15 patients with mild hypertension and NIDDM. Eight patients were treated with candesartan (8 to 16 mg per day) and 7 with enalapril (10 to 20 mg per day) for 1 year. Each patient underwent a biopsy of the subcutaneous fat from the gluteal region at baseline and after 1 year of treatment. Small arteries were dissected and mounted on a micromyograph and the media-to-internal lumen ratio was evaluated; moreover, endothelium-dependent vasodilation to acetylcholine was assessed. A similar blood pressure-lowering effect and a similar reduction of the media-to-lumen ratio of small arteries was observed with the 2 drugs. Vascular collagen content was reduced and metalloproteinase-9 was increased by candesartan, but not by enalapril. Changes of circulating indices of collagen turnover and circulating matrix metalloproteinase paralleled those of vascular collagen. The 2 drugs equally improved endothelial function. In conclusion, antihypertensive treatment with drugs that inhibit the renin-angiotensin-aldosterone system activity is able to correct, at least in part, alterations in small resistance artery structure in hypertensive patients with NIDDM. Candesartan may be more effective than enalapril in reducing collagen content in the vasculature.

Objective: 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.Design and methods: 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.Results: 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.Conclusions: 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.