细胞外镁离子调节大鼠舌下腺腺泡细胞内的钠离子浓度。

Extracellular Mg2+ regulates the intracellular Na+ concentration in rat sublingual acini.

作者信息

Zhang G H, Melvin J E

机构信息

Department of Dental Research, University of Rochester Medical Center, NY 14642, USA.

出版信息

FEBS Lett. 1997 Jun 30;410(2-3):387-90. doi: 10.1016/s0014-5793(97)00624-8.

DOI:10.1016/s0014-5793(97)00624-8

PMID:9237668

Abstract

The intracellular free Na+ concentration ([Na+]i) increases during muscarinic stimulation in salivary acinar cells. The present study examined in rat sublingual acini the role of extracellular Mg2+ in the regulation of the stimulated [Na+]i increase using the fluorescent sodium indicator benzofuran isophthalate (SBFI). The muscarinic induced rise in [Na+]i was approximately 4-fold greater in the absence of extracellular Mg2+. When Na+ efflux was blocked by the Na+,K+-ATPase inhibitor ouabain, the stimulated [Na+]i increase was comparable to that seen in an Mg2+-free medium. Moreover, ouabain did not add further to the stimulated [Na+]i increase in an Mg2+-free medium suggesting that removal of extracellular Mg2+ may inhibit the Na+ pump. In agreement with this assumption, ouabain-sensitive Na+ efflux and rubidium uptake were reduced by extracellular Mg2+ depletion. Our results suggest that extracellular Mg2+ may regulate [Na+]i in sublingual salivary acinar cells by modulating Na+ pump activity.

摘要

在毒蕈碱刺激唾液腺泡细胞过程中，细胞内游离钠离子浓度（[Na⁺]i）会升高。本研究使用荧光钠指示剂间苯二甲酸苯并呋喃酯（SBFI），在大鼠舌下腺泡中检测细胞外镁离子（Mg²⁺）在调节毒蕈碱刺激引起的[Na⁺]i升高方面的作用。在没有细胞外Mg²⁺的情况下，毒蕈碱诱导的[Na⁺]i升高大约大4倍。当Na⁺外流被Na⁺,K⁺-ATP酶抑制剂哇巴因阻断时，刺激引起的[Na⁺]i升高与在无Mg²⁺培养基中观察到的相当。此外，哇巴因在无Mg²⁺培养基中并未进一步增加刺激引起的[Na⁺]i升高，这表明去除细胞外Mg²⁺可能会抑制Na⁺泵。与这一假设一致，细胞外Mg²⁺耗竭会降低哇巴因敏感的Na⁺外流和铷摄取。我们的结果表明，细胞外Mg²⁺可能通过调节Na⁺泵活性来调节舌下唾液腺泡细胞中的[Na⁺]i。