Quamme G A, Smith C M
Am J Physiol. 1984 May;246(5 Pt 2):F544-50. doi: 10.1152/ajprenal.1984.246.5.F544.
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.
通过体外灌注评估兔近端直小管中的镁转运。从管腔到浴液的镁转运低于钠和钙的分数吸收率。因此，小管液镁浓度随水吸收而增加。从高膳食镁摄入量的兔获得的近端直小管中的镁转运与正常动物没有差异，这表明肾小管功能几乎没有变化（如果有变化的话也很小）。浅表和近髓近端直小管之间的镁通量没有明显差异。为了评估从浴液到管腔的镁通量，用含零镁浓度的溶液灌注小管。镁从浴液到管腔的移动很小，并且取决于跨上皮镁浓度梯度。如果完整肾脏中存在从间质到管腔的适当浓度梯度，这种镁内流可能足以解释镁的净进入。
