Mutsuo Sudo

Renal Hemodynamics in Oliguric and Nonoliguric Acute Renal Failure of Rabbits

The role of renal hemodynamic alterations in the curtailment of renal functions was studied in uranyl acetate-induced oliguric (ORF) and nonoliguric (NORF) renal failures of rabbits. 5 days after drug injection, renal functional and morphological changes were most remarkable. A depression of Cin and elevation of serum creatinine concentration were more marked in ORF than in NORF. Renal blood flow was high as compared to controls. Cortical blood flow redistributed to the inner cortex. There was no significant difference in renal blood flow or cortical flow distribution between renal failure models. The findings suggest the minor roles of renal blood flow and cortical flow distribution in maintaining renal failure in these nephrotoxic models. Prominent tubular necrosis was found in ORF but not in NORF. Arterial inulin concentration during retrograde ureteral infusion of 14C-inulin solution was significantly high in ORF as compared to controls and NORF. However, this inulin leakage was too small to explain severely curtailed inulin clearance.

Renal Handling of Salt and Water in the Early Stage of Obstructive Jaundice in Rabbits

Renal handling of salt and water in the early stage of obstructive jaundice was studied in rabbits 10 days after the ligation of the common bile duct (BDL). Sham-operated (SO) animals served as controls. No sodium retention was found in BDL rabbits, despite reduced renal perfusion and elevated plasma aldosterone level. A redistribution of intrarenal blood flow was not found. The filtration fraction did not change. A saline load resulted in decreases in arterial hematocrit and total serum proteins, and increases in urine output, urinary sodium excretion and osmolal clearance. Blood pressure, glomerular filtration rate (GFR), RPF, the filtration fraction and the intrarenal flow distribution were not significantly affected by the saline load. No significant difference was found in the natriuretic response to the saline load between the BDL and SO groups. After 60 h of water deprivation, there was no significant difference in urine-to-plasma osmolality ratios or renal tissue fluid osmolality between the BDL and SO animals. The findings indicate that renal handling of salt and water was well maintained in the early phase of obstructive jaundice in rabbits. The data also suggest the critical role of the redistribution of intrarenal blood flow rather than of GFR or aldosterone in determining sodium retention in obstructive jaundice.