Phosphate transport across the basolateral membrane of chick kidney proximal tubule cells.
Characterization of the phosphate transport system across the basolateral membrane of renal proximal tubule has been attempted using isolated proximal tubule cells prepared from chicks. The Pi efflux system is independent of Na+ ions and is not influenced by the nature of the chief anion present in the bathing medium. Pi efflux is not sensitive to DIDS and it is concluded that a generalized anion transporter of band III type is not the chief agent for facilitating Pi exit from the cell across the basolateral membrane. Inhibition of efflux by vanadate is evidence for a specific carrier protein in the membrane. The carrier probably possesses thiol group(s) that are essential for activity. The carrier may effect electroneutral transport of Pi possibly in exchange for OH- ions. The activity of the transport process is not stimulated by depleting the cells of phosphate or inhibited by rearing the chicks on a vitamin D-deficient diet. The system is unlikely to be of great importance for the expression of various regulatory mechanisms that act on the kidney to control the excretion of Pi. The activity declines as the chicks mature however.
Myint
S
S
Department of Biochemistry, King's College (KQC), London, U.K.
Butterworth
P J
PJ
D000367:Age Factors; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002645:Chickens; D003600:Cytosol / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007687:Kidney Tubules, Proximal / Q000187:drug effects / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism* / Q000494:pharmacology; D012964:Sodium / Q000494:pharmacology; D013439:Sulfhydryl Reagents / Q000494:pharmacology; D014808:Vitamin D Deficiency / Q000378:metabolism
D010710:Phosphates; D013439:Sulfhydryl Reagents; D012964:Sodium