Exercise-induced microalbuminuria in diabetes is associated with the urinary excretion of cationic proteins.

Urinary protein components, highly cationic in nature (pI 10.9), with apparent molecular weights of 65 kD, 45 kD, and 28 kD were detected in type I diabetic patients before (2/7), during (4/7) and after (1/7) exercise. Based on the apparent isoelectric point and molecular weights, the urinary cationic components in the urines of type I diabetic patients were superimposable to purified cationic proteins derived from human platelets. Furthermore, they also shared common antigenic components as evidenced by the ability of a goat anti-human platelet-derived cationic protein serum to immunoprecipitate the 45 kD protein fraction. The latter induced vascular permeability when injected intradermally in the rabbit's skin. The occurrence of urinary cationic proteins was associated with the significant increase in albumin excretion rate (AER) in diabetic patients. No urinary cationic components were ever detected in the urines of 6 healthy subjects before, during, or after exercise. The possible pathogenetic relevance of the urinary excretion of cationic proteins in diabetic AER is discussed.