Renal clearances in pigs. Inulin, endogenous creatinine, urea, para-amino-hippuric acid, sodium, potassium, and chloride.

Renal clearance studies were performed on 31 unanaesthetized pigs weighing from 28 to 123 kg. These included simultaneous determination of clearance, at constant plasma concentrations, of inulin, endogenous creatinine, urea, para-aminohippuric acid, sodium, potassium and chloride. The clearances found, calculated per 10 kg body weight, are as follows: inulin 21 ml/min., endogenous creatinine 22 ml/min., urea (max. clearance) 12 ml/min., para-aminohippuric acid 64 ml/min., sodium 0.015 ml/min., potassium 2.8 ml/min. and chloride 0.11 ml/min. It was also shown that inulin is a filtration substance in pigs, since clearance is independent of the rate of urine flow from 0.07 to 1.91 ml/min./10 kg, and of variations in inulin concentration in plasma from 40 to 1900 µg/ml. The average ratio between clearance of inulin and endogenous creatinine was 1.0, varying from 0.8 to 1.2. The filtration fraction (C/C) was determined at 0.33 and the max. tubular excretion of PAH at 23 mg/min./10 kg. The percentage extraction of PAH, determined on anaesthetized pigs, was found to be 87 %. The total renal blood flow was calculated to be 133 ml/min./10 kg body weight or 363 ml/min./100 g kidney.