Effects of vasodilators on peritoneal membrane permeability and lymphatic absorption in rats on peritoneal dialysis

We examined the effects of vasodilators on rat peritoneal membrane permeability and lymphatic absorption. Rats with normal kidney function weighing approximately 300g were dialyzed by infusing hypertonic dialysate (dextrose concentration: 3.86%) into the peritoneal cavity and allowing it to remain there for 4 hours. An angiotensin converting enzyme inhibitor (captopril), three calcium channel blockers (nicardipine, diltiazem, verapamil) and an α-blocker (moxisylite) were administered intraperitoneally. Transcapillary ultrafiltration volume (TCUFV) and lymphatic absorption volume (LAV) were calculated from changes in the intraperitoneal concentration of dextran 70 as well as net ultrafiltration volume (UFV), urea N clearance and glucose absorption. All vasodilator agents except moxisylite produced a significant increase in lymphatic absorption with a small increase in membrane permeability resulting in decreased net UFV. In conclusion, vasodilator agents, such as angiotensin converting enzyme inhibitors and calcium channel blockers, have the potential to decrease net UFV by increasing lymphatic absorption, and this must taken into account in patients being treated with antihypertensive drugs.