The renal clearance test was carried out in 6 normal male cats and 12 male cats with
chronic renal failure. The average concentrations of
creatinine (Cr),
urea,
sodium (Na), and
potassium (K) in the serum of the cats with
chronic renal failure were 5.09, 136.7 (mg/100 ml), 143.9 and 3.71 (mEq/l) respectively, and the specific gravity of urine was 1.009. The renal clearances of Cr,
urea, Na, and K (ml/min/kg of
body weight) were 2.639 +/- 0.217, 1.034 +/- 0.110, 0.024 +/- 0.007 and 0.266 +/- 0.028, respectively in normal cats, and were 0.789 +/- 0.407, 0.358 +/- 0.211, 0.095 +/- 0.084 and 0.872 +/- 0.204 in cats with
chronic renal failure. Clearance of Cr and
urea was significantly lower in cats with
chronic renal failure than in normal cats, while the values of Na and K were significantly higher in cats with
chronic renal failure. The glomerular filtration of Cr and
urea and the urinary excretion of these 4 substances were significantly higher in cats with
chronic renal failure. The tubular reabsorption rates of Na and K were significantly lower in cats with
chronic renal failure compared to those in normal cats, but there was no significant difference in
urea and
creatinine.