Abstract
PRO/Re mouse, a model of Type-I hyperprolinemia in man, provides the first occasion to examine the role of tissue oxidation in net reabsorption of an amino acid. Proline oxidase activity in PRO/Re kidney cortex is 2% of normal. Plasma pro is 0.7mM (10x normal) and the renal cortex pro is 1.3mM (4x normal). Net tubular reabsorption of pro is abnormally depressed in PRO/Re mice, but PRO/Re kidney takes up pro in vivo against a normal chemical gradient across the luminal membrane from urine & across peritubular membranes from blood. PRO/Re kidney cortex slices convert less L-pro at 1.2mM to CO2 and retain 3x more in the form of pro vs normal slices. Concentration-dependent uptake of L-pro (0.02-10mM) across basilar membranes in slices is mediated by more than one system; affinity of these systems for L-pro is normal in PRO/Re kidney; however steady-state distribution ratios & net uptake rates are depressed in PRO/Re. These findings reveal that hyperprolinuria can result not only from saturation of absorption, but also from exaggerated efflux from cell to urine because of abnormal intrarenal pro accumulation.
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Mcinnes, R., Mohyuddin, F. & Scriver, C. TRANSEPITHELIAL TRANSPORT OF L-PROLINE IN THE BLOCKED CATABOLIC MUTANT PRO/Re (HYPERPROLINEMIC) MOUSE. Pediatr Res 8, 391 (1974). https://doi.org/10.1203/00006450-197404000-00308
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DOI: https://doi.org/10.1203/00006450-197404000-00308