Effect of antihypertensive therapy on renal artery structure in type 2 diabetic rats with hypertension.

We have previously demonstrated that antihypertensive treatment with doxazosin (DZN), an alpha-adrenergic blocker, and lisinopril (LIS), an ACE inhibitor, reverse glomerular sclerosis in corpulent spontaneously hypertensive rats with type 2 diabetes. In this study, we examined the effects of the above-mentioned antihypertensive drugs alone and in combination on the structure of interlobular and arcuate arteries in these rats. Both male and female rats aged 6 months were treated with antihypertensive drugs for 16 weeks. Various structural parameters were evaluated by light microscopy, with the use of digital image analysis, in kidney sections stained with periodic acid-SCHIFF: Systolic blood pressure was significantly lower in treated than in untreated rats. Untreated diabetic rats had a significantly higher media/lumen ratio (smaller luminal diameter) of both arteries compared with the ratio in treated rats (for interlobular artery, 0.72+/-0.06 [no treatment], 0.49+/-0.03 [DZN treatment], 0.54+/-0.06 [LIS treatment], and 0.52+/-0.04 [combination therapy], P<0.05 to <0.001 for no treatment versus treatment; for arcuate artery, 0.66+/-0.11 [no treatment], 0.40+/-0.02 [DZN treatment], 0.39+/-0.04 [LIS treatment], and 0.40+/-0.03 [combination therapy], P<0.05 for no treatment versus treatment). Antihypertensive treatment caused significant increases in total arterial cross-sectional area, internal and external diameters, luminal and medial cross-sectional area, and medial thickness in both interlobular and arcuate arteries. The improvement in arterial structure after antihypertensive treatment was due to remodeling and growth of the vessels. Both DZN and LIS were equally efficacious, and combination therapy had no additive or synergistic effect.