In vitro effects of angiotensin II on glomerular function

Abstract

Effects of incubation with angiotensin II (ANG II) on isolated rat glomeruli were studied to test the hypothesis that ANG II exerts a direct effect on glomerular ultrafiltration coefficient (Kf) or hydraulic conductivity (Lp). Glomeruli of adult Munich-Wistar rats were isolated in isotonic medium and incubated at 37 degrees C in control medium or in medium containing ANG II (5.3 X 10(-9) to 5.3 X 10(-6) M) for 20 min. Glomerular volume decreased after incubation with ANG II. Relative volume decrement of unselected cortical glomeruli averaged 6 +/- 3% in 5.3 X 10(-9) or 10(-8) M ANG II and 13 +/- 3% in 5.3 X 10(-6) M ANG II; volume of superficial cortical glomeruli and deep cortical glomeruli diminished by 9 +/- 2 and 5 +/- 0.5%, respectively, after incubation with ANG II 5.3 X 10(-6) M. Glomerular oncometric response after equilibration with media of differing protein concentrations was not altered by ANG II incubation. Kf and Lp assessed in samples of glomeruli following ANG II incubation averaged 4.5 +/- 0.5 nl X mm-1 X mmHg and 2.7 +/- 0.5 microliter X mm-1 X mmHg X cm2, respectively, and were not significantly different from control values (3.8 +/- 0.3 nl X mm-1 X mmHg and 2.4 +/- 0.3 microliter X mm-1 X mmHg X cm2, respectively. In replicate studies of individual glomeruli prior to and after ANG II incubation, Kf was also not significantly altered (control Kf, 6.1 +/- 1.1; Kf after ANG II, 4.4 +/- 0.9 nl X min-1 X mmHg).(ABSTRACT TRUNCATED AT 250 WORDS)