Blood pressure lowering diminishes age-related changes in the rat aortic intima

These studies were undertaken to determine whether age-related changes in the aortic intima can be inhibited by prolonged blood pressure lowering. Normotensive Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) were treated with a combination of chlorothiazide, reserpine, and hydralazine beginning at 20 weeks of age and continuing until 62 weeks. Aortic morphology was assessed at the termination of the study by light and electron microscopy. Average systolic blood pressures during the final 6 months of therapy were: for untreated WKY, 147 +/- 5 mm Hg (mean +/- SE); for treated WKY, 110 +/- 2; for untreated SHR, 206 +/- 3; and for treated SHR, 104 +/- 4. Intimal and medial abnormalities were maximal in untreated SHR, while untreated WKY showed moderate changes consistent with their age. In contrast, both treatment groups exhibited relatively minimal alterations despite their advanced age. The occurrence of intimal lesions in individual animals correlated with the average level of blood pressure during therapy. These data suggest that blood pressure reduction, even in normotensive animals, may reduce the effects of aging on the arterial wall.