Characteristics of cystine and lysine transport in renal and jejunal tissue from cystinuric dogs

Abstract

Canine cystinuria differs from the human situation in two respects. Lysinuria was present in 10 of 14 cystinuric dogs, however the molar ratio of lysine excretion did not exceed that of cystine, although it commonly does in the human disease. Excessive excretion of other dibasic amino acids, ornithine and arginine, was not found in the dogs. Using conditions which demonstrate an in vitro transport defect in intestinal epithelial cell accumulation of cystine and lysine by human cystinuric jejunal mucosa, cystine and lysine accumulation by jejunal mucosa from cystinuric dogs was normal. No defect in cystine or lysine accumulation by renal cortical slices was demonstrated. It appears that isolated cystinuria occurs more frequently in the canine population than in humans, and epithelial cell transport defects of cystine and lysine cannot be demonstrated.