Effect of parathyrin on the transport properties of isolated renal brush-border vesicles.
The transport properties of brush-border membrane vesicles isolated by a calcium-precipitation method from the renal cortex of normal and parathyrin (parathyroid hormone)-treated rats were studied by a rapid-filtration technique. Parathyrin elicited a dose-dependent decrease in the Na+-dependent phosphate uptake by the brush-border membrane vesicles, but the uptake of D-glucose, Na+ and mannitol was not affected. A maximum inhibition of 30% was observed after the application of 30 U.S.P. units intramuscularly 1 h before the animals were killed. Intravenous infusion of dibutyryl cyclic AMP (0.5-1.5 MG) also decreased the phosphate uptake by the brush-border vesicles. Both dibutyryl cyclic AMP and parathyrin were ineffective when added in vitro to brush-border membrane vesicles isolated from normal rats. These data suggest that parathyrin exerts its action on the phosphate reabsorption in the renal proximal tubule by affecting the Na+/phosphate co-transport system in the brush-border membrane. The effects of parathyrin on Na+ and glucose transport, however, seem to be due to alterations to the driving forces for transport and not to the brush-border transport systems.
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D000242:Cyclic AMP / Q000494:pharmacology; D066298:In Vitro Techniques; D007672:Kidney Cortex / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D007687:Kidney Tubules, Proximal / Q000187:drug effects / Q000378:metabolism; D007700:Kinetics; D008297:Male; D008871:Microvilli / Q000378:metabolism; D010281:Parathyroid Hormone / Q000494:pharmacology*; D010710:Phosphates / Q000378:metabolism; D051381:Rats; D014667:Vasopressins / Q000494:pharmacology
D010281:Parathyroid Hormone; D010710:Phosphates; D014667:Vasopressins; D000242:Cyclic AMP