ANGIOTENSIN-II MODULATES GLOMERULAR CAPILLARY PERMSELECTIVITY IN RAT ISOLATED-PERFUSED KIDNEY

Studies in experimental animals and humans have documented that inhibi tion of the renin-angiotensin system by angiotensin-converting enzyme inhibitors reduces urinary protein excretion rate and retards the deve lopment of renal injury, Here we sought to investigate whether angiote nsin II (All) modified the size-selective properties to macromolecules of the glomerular capillary barrier in isolated perfused rat kidney p reparation. Compared with basal values, continuous All infusion into t he renal artery at the rate of 3 or 8 ng/min, but not at 0.6 ng/min, i nduced a progressive and significant increase in urinary protein excre tion rate. Evaluation of the sieving properties of the glomerular barr ier by fractional clearance of polydisperse Ficoll showed that All sig nificantly enhanced the filtration of tracer molecules of radii greate r than or equal to 34 Angstrom. All-induced changes in urinary protein excretion rate and in Ficoll fractional clearance were completely pre vented by pretreatment with the specific All Type 1 receptor antagonis t SR 47436.