Na+ gradient-dependent Pi uptake in basolateral membrane vesicles from dog kidney.
Na+ gradient-dependent Pi uptake in basolateral membrane vesicles from dog kidney.
复制标题
狗肾基底外侧膜囊泡中 Na 梯度依赖性 Pi 吸收。
DOI：
10.1152/ajprenal.1984.246.5.f663
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发表时间：
1984
期刊：
影响因子：
--
通讯作者：
Hammerman,MR
中科院分区：
文献类型：
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作者：
Schwab,SJ;Klahr,S;Hammerman,MR
为了确定Na+梯度刺激的32 - pi摄取是否在肾基底外侧膜囊中被证实，我们测量了从犬肾皮质分离的基底外侧膜悬浮液的32 - pi摄取，并比较了基底外侧悬浮液和刷缘悬浮液的溶质摄取。测量显示Na+梯度依赖的32Pi在基底外侧的转运。基底侧悬浮液中的D-[3H]葡萄糖摄取没有受到Na+梯度的刺激，这与刷状边界悬浮液中的结果相反。基底侧悬浮液中Na+梯度相关的32Pi输运是电致的，与刷状边缘制剂中测量的结果相反。与刷状边缘制剂中32Pi的摄取不同，当泡外pH从6.5增加到7.5时，基底侧悬浮液中Na+梯度依赖性32Pi的摄取并没有增加。基底膜中Na+梯度依赖的32Pi摄取在[Pi] 5至100微米范围内显示饱和（表观Km， 14 +/- 2微米；表观Vmax， 34 +/- 2 pmol Pi X mg蛋白-1 X 30s-1）。我们的研究结果与犬近端管状基底外膜中存在电致Na+-Pi共转运蛋白相一致。
To ascertain whether Na+ gradient-stimulated 32Pi uptake was demonstrable in renal basolateral membrane vesicles, we measured 32Pi uptake in basolateral membrane suspensions isolated from canine renal cortex and compared solute uptake in basolateral suspensions with that measured in brush border suspensions. Measurements revealed Na+ gradient-dependent 32Pi transport in basolateral preparations. D-[3H] Glucose uptakes in basolateral suspensions were not stimulated by the Na+ gradient in contrast to findings in brush border suspensions. Na+ gradient-dependent 32Pi transport in basolateral suspensions was electrogenic in contrast to that measured in brush border preparations. Unlike 32Pi uptake in brush border preparations, Na+ gradient-dependent 32Pi uptake in basolateral suspensions did not increase as extravesicular pH was increased from 6.5 to 7.5. Na+ gradient-dependent 32Pi uptake in basolateral membranes showed saturation over the range of [Pi] from 5 to 100 microM (apparent Km, 14 +/- 2 microM; apparent Vmax, 34 +/- 2 pmol Pi X mg protein-1 X 30s-1). Our findings are compatible with the presence of an electrogenic Na+-Pi cotransporter in the canine proximal tubular basolateral membrane.