Renovascular hypertension - Structural changes in the renal vasculature

Experimental narrowing of the main renal artery to produce hypertension inc reases the aorta-glomerular capillary pressure difference and vascular resi stance. This article examines the hypothesis that hypertension also ma!, be caused by structural changes that narrow intrarenal blood vessels, similar ly increasing preglomerular vascular resistance and the aortic-glomentlar c apillary pressure gradient. There is evidence of both wall hypertrophy and lumen narrowing of the preglomerular arteries in spontaneously hypertensive rats, with increased preglomerular resistance and aortic-glomerular capill ary pressure difference. We have also attempted to induce structural change s in renal-preglomerular vessels experimentally by infusing angiotensin II at low doses (0.5 to 4.5 ng/kg per minute) into the renal artery of Spragru e-Dawley rats and greyhound dogs for up to 4 weeks. This angiotensin IT inf usion produced apparent dose-related effects on preglomerular vessel struct ure and hypertension. The possibility that hypertension may be induced by s tructural changes in preglomerular resistance vessel walls, by simulation o f the hemodynamic effects of main renal artery stenosis, deserves further i nvestigation.