Effect of angiotensin II(VII) on peritoneal transport during peritoneal dialysis in rat

Ultrafiltration volume (UFV) in peritoneal dialysis is expressed as the difference between net transcapillary ultrafiltration (TCUF) and lymphatic absorption (LA) in peritoneal cavity. An increase in LA results in a decrease in UFV. Endogenous hormones may modulate peritoneal membrane permeability and LA. This study was conducted to assess the effect of angiotensin II(AII) on peritoneal permeability and LA in rat. Rats (BW, approximately 300g) with normal renal function were dialyzed for 4 hours using 30m1 of hypertonic dialysate (dextrose concentration: 3.86%). AII was added in dialysate at the concentration of 10-9-10-2 mol/30ml. Peritoneal membrane permeability and UFV were studied by clearance of urea N and inorganic phosphate, albumin excretion, glucose absorption and LA. LA was calculated by the concentration change of dextran 70 in dialysate. AII decreased UFV from 15. 7±2. 8ml/4hr(control) to 5.7±1.5(VII10-4 mol/dwell). LA was increased in a dose dependent fashion (ED50: 0.25×10-6mol) with no change in TCUF and clearances of urea N and inorganic phosphate. Ten types of AII analogue were used to investigate the site of action for LA in 8 amino acids of AII. [β-Asp1], [Val5], [Ile3, Val5] and [Sar1] AII showed agonistic action against LA. [Sar1, Thr8], [Sar1, Ile8], [Sar1, Leu8], [Sar1, Ala8], [Sar1, Val5, Ala8] and [Sar1, Gly8] AII had no effect on LA, which found the importance of the 8th amino acid of AII for LA. These actions of AII analogue against LA were similar to those for vascular smooth muscle. An increase in LA with AII was reduced by 40% in the rat with a sealing diaphragm. In conclusion, peritoneal administration of AII decreased UFV by an enhancement of LA. Subdiaphragmatic lymph system played an important role for this increase in LA.