Wong N L, Dirks J H
Department of Medicine, Health Sciences Centre Hospital, University of British Columbia, Vancouver, Canada.
Ren Physiol. 1987;10(5):242-8. doi: 10.1159/000173132.
In vitro microperfusion experiments were performed on the cortical proximal straight tubule of the rabbit to examine the effect of acid base disturbances on calcium and magnesium transport by this segment of the nephron. During acidosis (pH 7.22 +/- 0.01) net calcium reabsorption was reduced, whereas during alkalosis (pH 7.82 +/- 0.02) net calcium reabsorption was increased. Our flux experiments with 45Ca indicate that the efflux of Ca from the lumen to the bath remained the same during acidosis; however, the back-flux (bath to lumen) of calcium increased. On the other hand, during alkalosis the efflux of calcium rose and the influx of calcium remained unchanged. These changes in fluxes during acid-base disturbances can be accounted for mainly by changes in ionized calcium as a result of pH changes. We failed to observe any effect of acid-base changes on net magnesium transport by the superficial proximal straight tubule.
在兔肾皮质近端直小管上进行了体外微灌注实验，以研究酸碱平衡紊乱对该肾单位节段钙和镁转运的影响。酸中毒（pH 7.22±0.01）时，钙的净重吸收减少，而碱中毒（pH 7.82±0.02）时，钙的净重吸收增加。我们用45Ca进行的通量实验表明，酸中毒时钙从管腔到浴液的流出量保持不变；然而，钙的反向通量（从浴液到管腔）增加。另一方面，碱中毒时钙的流出量增加，钙的流入量保持不变。酸碱平衡紊乱期间通量的这些变化主要可归因于pH变化导致的离子化钙的变化。我们未观察到酸碱变化对浅表近端直小管镁净转运的任何影响。
