Developmental aspects of proline transport in rat renal brush border membranes.

AUTOR(ES)

Medow, M S

RESUMO

Proline uptake by rat renal brush border membrane vesicles from animals 7 days of age and older has been examined to delineate developmental changes in membrane function that may underlie the physiological hyperprolinuria of young animals. Although the two proline transport systems normally present in adult membranes were found in membranes from young animals, the proline "overshoot" resulting from a sodium ion gradient is minimal and increases with age of the animal from which the membranes were isolated. This is associated with a severalfold faster entry of 22Na into vesicles of the 7-day-old animal compared to entry into membranes prepared from adult kidneys. The very rapid dissipation of the sodium gradient thus diminishing the driving force for transmembrane proline movement may explain the changes in proline overshoot observed in membranes from young animals. The altered sodium permeability is consistent with the fact that young animals have a generalized inability to reabsorb other amino acids whose transport is known to be sodium gradient stimulated.

Documentos Relacionados

• Electrophysiology of succinate transport across rabbit renal brush border membranes.
• Thyroid hormones increase Na+-H+ exchange activity in renal brush border membranes.
• Cholesterol modulates rat renal brush border membrane phosphate transport.
• Identification of the human NHE-1 form of Na(+)-H+ exchanger in rabbit renal brush border membranes.
• Binding of Escherichia coli heat-stable enterotoxin to rat intestinal cells and brush border membranes.