Influence of chronic hypertension on injured and uninjured arteries in spontaneously hypertensive rats.

The influence of chronic essential hypertension in spontaneously hypertensive rats (SHR) on uninjured and deendothelialized arteries was investigated in two models of arterial endothelial injury (aortic balloon and carotid air injury). SHR rendered normotensive with antihypertensive medication (hydralazine, reserpine, and furosemide), normotensive Wistar rats, and Wistar rats treated with antihypertensive drugs served as controls. In uninjured vessels, slight intimal thickening and marked medial thickening were found in SHR but not controls. In injured vessels, endothelial regeneration was similar in SHR and controls. Intimal thickening due to smooth muscle cell proliferation was markedly enhanced in SHR compared to drug-treated SHR, whereas medial thickening in the injured vessels of SHR did not change over the time interval studied. Administration of drug to normotensive Wistar rats did not affect myointimal or medial thickening. These results indicate that acute arterial endothelial injury in chronically hypertensive rats produces marked myointimal thickening that can be controlled with antihypertensive medication.