Effects of cilazapril on the structure of mesenteric resistance arteries of New Zealand genetically hypertensive and normotensive control rats.

1. New Zealand genetically hypertensive (GH) rats and their normotensive controls (N) rats between the ages of 10 and 16 weeks were treated with cilazapril in the diet for 6 weeks. 2. Systolic blood pressure (SBP; tail-cuff) was measured weekly and intra-arterial blood pressure (BP) was measured at the end of the treatment period. 3. The effect of cilazapril on the structure of mesenteric resistance arteries (MRA) was evaluated by both stereological and myographic techniques. 4. Cilazapril lowered SBP significantly throughout the treatment period (16 weeks; GH with cilazapril 135 +/- 5 vs GH 216 +/- 9 mmHg, P < 0.001; N cilazapril 91 +/- 6 vs N 137 +/- 3 mmHg, P < 0.001); intra-arterial BP was also significantly lowered. 5. Bodyweight (BW) of treated GH rats was significantly lower than that of untreated GH at 16 weeks (P < 0.01; t-test); however, the weight of treated N rats was not significantly affected. Ventricular mass was reduced by cilazapril in GH and N rats (GH 259 +/- 10 vs 306 +/- 11, P < 0.001; N 171 +/- 3 vs 195 +/- 4 mg/100 g BW, P < 0.001). 6. Lumen volume of MRA was not significantly affected by cilazapril in either strain; media volume was reduced by 14% in both strains and the media/lumen ratio was significantly reduced. Vascular smooth muscle cell density significantly increased in cilazapril-treated GH rats.