Reducing pulse pressure in hypertension may normalize small artery structure.

Abstract

To investigate the relation between the small artery structure and different blood pressure parameters, spontaneously hypertensive rats were treated from 4 to 24 weeks of age (20 weeks in total) with five different antihypertensive therapies: two angiotensin converting enzyme inhibitors (perindopril and captopril), a calcium antagonist (isradipine), a beta-blocker (metoprolol), and a vasodilator (hydralazine). At 24 weeks of age, 24-hour blood pressure was measured, and two mesenteric resistance vessels were taken from each animal. Blood pressure was 227/135 mm Hg (systolic/diastolic) and 161/106 mm Hg in untreated hypertensive and normotensive control rats, respectively. Heart rates were 376 min-1 and 295 min-1 for the two strains. All treatments reduced all blood pressure parameters except for metoprolol, which did not reduce pulse pressure. In the small arteries, the media cross-sectional area was unaffected by the treatments. When a simple correlation analysis was made, pulse pressure was found to correlate more closely (r = 0.64, p less than 0.001) to the resistance vessel media/lumen ratio than any of the other pressure parameters studied: systolic (r = 0.51, p = 0.011), mean (r = 0.41, p = 0.05), or diastolic (r = 0.28, p = 0.19). When an analysis of covariance was performed that included pulse pressure, mean blood pressure, and heart rate, which also correlated significantly to the media/lumen ratio, 81% of the variation in the media/lumen ratio could be accounted for by the variation in the three covariates (p less than 10(-5)), pulse pressure being the major factor.(ABSTRACT TRUNCATED AT 250 WORDS)