Physiological proteinuria in healthy animals
Gärtner, K.
Deutsche Tierärztliche Wochenschrift 88(10): 420-422
1981
ISSN/ISBN: 0341-6593 PMID: 7040036 Document Number: 180806
The protein content of the urine is about 0.1; 0.08; 0.5-1 and 8-25 mg/ml in healthy men, dogs, rats and mice, respectively. The content of albumin in the urine is similar in all four species (0.02-0.05 mg/ml). The conditions of the albumin filtration in the glomeruli are assumed to be similar in all four species. (Sieving coefficient of albumin 0.0002-0.0004.) On the other hand the maximum reabsorption rate for albumin in the tubules differs greatly between species. In rats, the maximum tubular reabsorption rate for albumin (9.6 mu g/min/g kidney) is near to the level of the normal rate of albumin filtration in the glomeruli. Therefore in rats, and also in mice, an increase of plasma albumin concentration above the normal value leads to a large increase in urinary albumin excretion. Apparently in dogs and men this threshold is higher. There is a contribution of low molecular weight proteins (MW 15 000-22 000) to the total renal protein excretion in rat and mice to 90 and 99%, respectively. These proteins are filtered nearly freely in the glomeruli and reabsorbed incompletely in the tubules. Some low molecular weight proteins function as pheromones in sexual and social behaviour.