Effect of low-phosphate diet on sodium/phosphate cotransport mRNA and protein content and on oocyte expression of phosphate transport.
Recently, we have isolated a complementary DNA most likely related to rabbit kidney cortex brush border membrane sodium/phosphate (Na/Pi) cotransport activity [NaPi-1 (1)]. To further elucidate the cellular mechanisms involved in dietary 'adaptation' of renal Na/Pi cotransport, we have exposed young rabbits for 2 weeks to either a low phosphate (Pi) diet (LPD) or a high Pi diet (HPD). Initial linear uptake of Na/Pi cotransport in isolated brush border membrane vesicles was increased in rabbits on a LPD compared with those on a HPD. Injection of equal amounts of total mRNA isolated from kidney cortex of LPD or HPD rabbits into Xenopus laevis oocytes resulted in a higher stimulation of Na-dependent oocyte Pi uptake in LPD than HPD preparations. No difference in the content of 'specific' mRNA (NaPi-1 cDNA probe, Northern blots) and of the content of the 'specific' brush border membrane protein (NaPi-1 antipeptide antibody, Western blots) between LPD and HPD preparations was observed. We conclude that 'chronic' dietary Pi deprivation leads to a protein synthesis-dependent alteration of Na/Pi cotransport activity which does not involve a change in the total amount of a protein related to the recently cloned NaPi-1 protein.
Biber
J
J
Department of Physiology, University of Zürich, Switzerland.
Caderas
G
G
Stange
G
G
Werner
A
A
Murer
H
H
D000818:Animals; D001693:Biological Transport, Active; D015153:Blotting, Western; D002352:Carrier Proteins / Q000378:metabolism*; D004032:Diet; D008871:Microvilli / Q000378:metabolism; D009865:Oocytes / Q000378:metabolism*; D010710:Phosphates / Q000008:administration & dosage / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis*; D011817:Rabbits; D050608:Sodium-Phosphate Cotransporter Proteins; D027981:Symporters; D014982:Xenopus laevis
D002352:Carrier Proteins; D010710:Phosphates; D012333:RNA, Messenger; D050608:Sodium-Phosphate Cotransporter Proteins; D027981:Symporters