Magnesium transport in the proximal straight tubule of the rabbit.
Magnesium transport was evaluated in proximal straight tubules of rabbits by in vitro perfusion. Magnesium transport from lumen to bath was less than the fractional absorption rates of sodium and calcium. Accordingly, the tubule fluid magnesium concentration increased with water absorption. Magnesium transport in proximal straight tubules obtained from rabbits maintained on high dietary magnesium intake was not different from normal animals, which suggests little, if any, change in tubular function. There were no discernible differences in magnesium fluxes between superficial and juxta-medullary proximal straight tubules. To assess bath-to-lumen magnesium flux, tubules were perfused with solutions containing zero magnesium concentration. Magnesium movement from the bath to lumen was small and dependent on the transepithelial magnesium concentration gradient. This magnesium influx may be sufficient to account for net magnesium entry provided the appropriate concentration gradients from interstitium to lumen are available in the intact kidney.
D000042:Absorption; D000818:Animals; D001692:Biological Transport; D002118:Calcium / Q000378:metabolism; D004032:Diet; D005260:Female; D007687:Kidney Tubules, Proximal / Q000378:metabolism*; D008274:Magnesium / Q000378:metabolism* / Q000494:pharmacology; D011817:Rabbits; D012964:Sodium / Q000378:metabolism
D012964:Sodium; D008274:Magnesium; D002118:Calcium