TRANSPORT OF CITRATE ACROSS RENAL BRUSH-BORDER MEMBRANE - EFFECTS OF DIETARY ACID AND ALKALI LOADING
TRANSPORT OF CITRATE ACROSS RENAL BRUSH-BORDER MEMBRANE - EFFECTS OF DIETARY ACID AND ALKALI LOADING
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DOI：
10.1152/ajprenal.1985.249.4.f590
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发表时间：
1985-01-01
影响因子：
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通讯作者：
SMITH, LH
中科院分区：
文献类型：
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作者：
JENKINS, AD;DOUSA, TP;SMITH, LH
通过提供150 mM NH 4Cl或150 mM NaHCO 3代替饮用水6天，给予大鼠膳食酸或碱负荷;对照动物接受150 mM NaCl。6天后，柠檬酸盐清除率为0.04 ±。0.01 ml/min（平均值±. SE），0.9 ±。0.1对照组为2.5 ± 0.5ml/min。0.2 ml/min。在实验结束时，处死大鼠，并在从各组制备的刷状缘膜（BBM）囊泡中测量Na+梯度依赖性（Nao+ > Nai+）柠檬酸盐摄取（pmol/mg蛋白质）。在0.3分钟时，[14 C]柠檬酸盐摄取为198 ± 0.0000。8 pmol/mg蛋白质（平均值±. SE），94 . ±.对照组为16 pmol/mg蛋白，对照组为94 ± 10 pmol/mg蛋白。13 pmol/mg蛋白。Na+非依赖性（培养基中的NaCl被KCl替代）[14 C]-柠檬酸盐被BBM囊泡摄取的速率对于酸负荷、对照和碱负荷动物是相同的。因此，近端管状BBM将柠檬酸盐从管腔转运到细胞内部的能力增加可能是在慢性饮食酸负荷诱导的代谢性酸中毒存在下导致尿柠檬酸盐减少的重要因素。
Dietary acid or alkali loading was given to rats by providing 150 mM NH4Cl or 150 mM NaHCO3 in place of drinking water for 6 days; control animals received 150 mM NaCl. After 6 days, the citrate clearance was 0.04 .+-. 0.01 ml/min (mean .+-. SE) in the acid-loaded group, 0.9 .+-. 0.1 ml/min in the control group, and 2.5 .+-. 0.2 ml/min in the alkali-loaded group. At the end of the experiment, the rats were killed, and the Na+ gradient-dependent (Nao+ > Nai+) citrate uptake (pmol/mg protein) was measured in brush border membrane (BBM) vesicles prepared from each group. At 0.3 min, the [14C] citrate uptake was 198 .+-. 8 pmol/mg protein (mean .+-. SE) in the acid-loaded group, 94 .+-. 16 pmol/mg protein in the control group, and 94 .+-. 13 pmol/mg protein in the alkali-loaded group. The rate of Na+-independent (NaCl in medium replaced by KCl) [14C]-citrate uptake by BBM vesicles was the same for acid-loaded, control, and alkali-loaded animals. thus, the increased capacity of the proximal tubular BBM to transport citrate from the tubular lumen into the cell interior may be an important factor that contributes to decreased urinary citrate in the presence of metabolic acidosis induced by chronic dietary acid loading.