Renal function studies in an experimental model of papillary necrosis in the rat (1)

Abstract

(5 figures) Twenty four hours after i.v. injection of bromoethylamine-hydrobromide (BEA) in rats, a uniform papillary necrosis is observed. The present study investigates the renal function and the papillary haemodynamics in response to acute volume expansion (12 % of body weight) in this model. Renal function studies were performed in hydropenic and volume expanded sham- or BEA-injected rats. In hydropenic normal animals a GFR of 1.97 ± 0.14 ml/ min, an urinary osmolality (U_Osm) of 1 001 ± 94.5 mOsm/kg and a fractional sodium excretion (FE_Na) of 0.18 ±0.026% were obtained. In contrast, BEA-treated hydropenic animals showed a lower GFR (1.16 ± 0.14 ml/min), U_Osm (469 ± 30.31 mOsm/kg) and a higher FE_Na (0.37 ± 0.06 %). In volume expansion a similar U_Osm and FE_Na were obtained in both groups. The papillary plasma flow (PPF) was measured in each of the experimental groups by the albumin accumulation technique. The mean value in hydropenic normal animals was 50.65 ± 2.12 ml 100 g⁻¹ min⁻¹ and increased to 66.03 ± 2.00 ml 100 g⁻¹ min⁻¹ after volume expansion (P < 0.001). In BEA rats the PPF was 58.86 ± 2.33 ml 100 g⁻¹ min⁻¹ in hydropenia (P < 0.01 vs. control animals) and remained unchanged after volume expansion. Thus, during hydropenia, BEA-induced papillary necrosis results with a salt wasting state and an urinary concentration defect. After volume expansion no disturbance in sodium excretion capacity was observed. These results are compatible with the nephron-heterogeneity concept in the regulation of sodium excretion. The histological lesions cannot be explained by a decreased renal papillary plasma flow.