Bikhazi A B, Medlej-Hashim M, el-Kasti M
Department of Physiology, Faculty of Medicine, American University of Beirut, New York, NY 10022.
J Pharm Sci. 1992 Dec;81(12):1178-80. doi: 10.1002/jps.2600811210.
A Sprague-Dawley rat kidney perfusion technique was used in situ to study the effect of verapamil, ouabain, and ethacrynic acid on renal calcium retention. The technique involves perfusion of the kidneys via the abdominal aorta and then through the left and right renal arteries and dorsal aorta. Verapamil (1 mM) in Krebs-improved Ringer solution increased calcium retention in the kidneys by approximately 117% compared with controls. With Na-free Krebs-improved Ringer solution, calcium retention increased by only 92%. However, in Krebs-improved Ringer solutions containing 59 and 122 mequivalents of Na, calcium retention in the kidney increased by 46 and 43%, respectively, compared with controls. With Krebs-improved Ringer solution containing 15 mM ouabain, calcium retention in the kidney decreased by 29.5%, whereas with 15 mM ouabain plus 1 mM ethacrynic acid in the perfusate, the effect on calcium retention in the kidney was insignificant compared with controls. These results suggest that two sodium-dependent calcium-transporting systems exist at the peritubular side of the kidney tubules: (1) a Na(+)-Ca+2 countertransport system sensitive to verapamil and (2) a Na(+)-Ca+2 cotransport system sensitive to the intracellular concentration of sodium.
采用斯普拉格-道利大鼠肾脏原位灌注技术，研究维拉帕米、哇巴因和依他尼酸对肾脏钙潴留的影响。该技术包括通过腹主动脉，然后经左右肾动脉和背主动脉对肾脏进行灌注。与对照组相比，在改良的克雷布斯林格液中加入1 mM维拉帕米可使肾脏钙潴留增加约117%。在无钠的改良克雷布斯林格液中，钙潴留仅增加92%。然而，在含有59和122毫当量钠的改良克雷布斯林格液中，与对照组相比，肾脏钙潴留分别增加46%和43%。在含有15 mM哇巴因的改良克雷布斯林格液中，肾脏钙潴留减少29.5%，而在灌注液中加入15 mM哇巴因加1 mM依他尼酸时，与对照组相比，对肾脏钙潴留的影响不显著。这些结果表明，在肾小管周侧存在两种钠依赖性钙转运系统：（1）对维拉帕米敏感的Na(+)-Ca+2逆向转运系统；（2）对细胞内钠浓度敏感的Na(+)-Ca+2同向转运系统。
