The development of glomerular structural abnormalities in remnant nephrons, after ablation of renal mass (subtotal nephrectomy), in rats is largely prevented by the daily injection of heparin. To investigate if this protective effect of heparin is due to attenuation of glomerular hyperperfusion, hypertension and hyperfiltration, which develop in remnant nephrons soon after subtotal nephrectomy, we measured various parameters of glomerular hemodynamics at two weeks (Group 1) and four weeks (Group 2) after removal of 1-3/4 of total kidney mass in heparin-treated (Groups 1A and 2A) and untreated (Groups 1B and 2B) Munich-Wistar rats. When compared to normal non-nephrectomized rats (Group 1C), the values for glomerular capillary hydraulic pressure (PGC), glomerular plasma flow rate (QA) and single nephron filtration rate (SNGFR) in remnant nephrons were found to be markedly and similarly elevated in both Groups 1A and 1B, averaging 71 +/- 4 and 73 +/- 4 mm Hg, 229 +/- 41 and 176 +/- 13 nl/min, 58.9 +/- 6.4 and 60.8 +/- 7.8 nl/min, respectively. Thus, glomerular hemodynamic parameters two weeks after subtotal nephrectomy did not differ between untreated and heparin-treated rats. Likewise, heparin treatment did not decrease the values of PGC and SNGFR assessed four weeks after subtotal nephrectomy, with the average values being 65 +/- 2 mm Hg and 83.8 +/- 7.1 nl/min in Group 2A versus 62 +/- 4 mm Hg and 63.7 +/- 6.5 nl/min in Group 2B.(ABSTRACT TRUNCATED AT 250 WORDS)