Dependency of Filtration and P-Aminohippurate (PAH) Secretion on Na Reabsorption in the Obstructed Dog Kidney. ∗

Creatinine and p-aminohippurate (PAH) accumulate in renal tissue during ureteral obstruction in oliguria and in mannitol diuresis (1). Accumulation of creatinine was not significantly different from inulin in experiments in which both substances were used. It was concluded that accumulation of creatinine could be attributed to persistent nitration during the period of obstruction. Although reabsorption of fluid from the lumen during stop-flow was suggested as the cause of persistent filtration, the relationship between these two variables was not established. A hypothesis has been devised to relate sodium reabsorption to glomerular filtration during stop-flow. Sodium reabsorption would be followed by reabsorption of water, and a hydrostatic pressure difference would be induced between the site of reabsorption and the glomerulus. Stop-flow filtration would result with intraluminal trapping of any non-reabsorbable substance.

The present report presents studies on renal tissue accumulation of creatinine and PAH in dogs loaded with sodium salts of mono-and multivalent anions. Results support the above hypothesis, that is, as the reabsorbability of the sodium salt increases the stop-flow filtration increases.

Methods. Following 24 hours of water and food deprivation, male and female mongrel dogs (16-20 kg) were anesthetized with Nembutal (30 mg/kg). Both ureters were catheterized. After an initial priming dose of creatinine and PAH was injected intramuscularly in amounts of 0.1 and 0.01 g/kg respectively, osmotic diuresis was induced by intravenous infusion of 1.0 osmolar solutions of the sodium salt of chloride, nitrate, bicarbonate, sulfate, or ferrocyanide at a rate of 10 ml/min. The infusion fluid also contained 0.4 g/kg/1 creatinine, 0.1 g/kg/1 PAH and 0.025 g/kg/1 KC1. The urine flow was maintained at a level of 5 ml/min or more per kidney for approximately 30 minutes preceding ureteral obstruction. The left ureter was obstructed for 50 minutes, and then both kidneys were quickly removed.