Effects of antihypertensive drugs on peritoneal vessels in hypertensive dogs with mild renal insufficiency.

The transport capacity of any membrane depends on its surface area and permeability. In addition, peritoneal capillaries are probably barriers to solute transport. Although no decisive use of antihypertensive drugs has been reported in continuous ambulatory peritoneal dialysis (CAPD) patients with hypertension, those drugs are known to have various effects on vessels. In the present study, we used a charge-coupled-device (CCD) camera in renovascular hypertensive dogs with mild renal insufficiency to investigate the effects of various antihypertensive drugs on the peritoneal capillaries. Renovascular hypertension was induced in the dogs by placing silver clips on both renal arteries to create 90% occlusion. After confirmation of elevation of blood pressure (usually 20 days after the operation), each dog's abdomen was opened while the animal was under general anesthesia. Using a CCD camera, the diameters of the small arteries of the peritoneum were measured after 3 days' oral administration of a placebo (n = 5); or of 8 mg CS866, a selective angiotensin II type 1 receptor blocker (n = 5); or of 10 mg benazepril, an angiotensin-converting enzyme inhibitor (n = 5); or of 10 mg amlodipine, a calcium antagonist (n = 5). In dogs receiving CS866, blood pressure decreased to 128 +/- 6 mmHg from 160 +/- 6 mmHg (p < 0.01). A similar decrease in blood pressure was observed with the use of the other drugs. The diameter of the small vessels increased by 28% +/- 6% in dogs receiving CS866 and by 24% +/- 5% in dogs receiving benazepril, as compared with 3% +/- 3% in dogs receiving the calcium antagonist. These data clearly demonstrate that blockade of the renin-angiotensin system produces an increase in solute clearance in hypertensive dogs with mild renal insufficiency and that such blockade may be applicable as therapy for hypertensive patients on CAPD.