Slotki I, Schwartz J H, Alexander E A
Thorndike Memorial Laboratory, Boston City Hospital, Massachusetts.
Am J Physiol. 1993 Aug;265(2 Pt 1):C432-8. doi: 10.1152/ajpcell.1993.265.2.C432.
In this study we investigated the interrelationship between cell pH (pHi) and cell calcium (Cai) in cultured inner medullary collecting duct cells of the rat. Confluent monolayers were made quiescent by incubation for 24 h in Dulbecco's modified Eagle's medium supplemented with 0.1% serum before study. Changes in pHi and Cai were measured with the fluorescent probes 2',7'-bis(carboxyethyl)-5,6-carboxyfluorescein and fura 2. In nominally bicarbonate-free media containing 110 mM Na+ and 1 mM Cai, cell acidification to pH 6.70 increased Cai from 122 +/- 24 to 243 +/- 33 nM. In the absence of bath calcium, acidification increased Cai from 90 +/- 7 to 144 +/- 13 nM. An increase of pHi to 7.6 reduced Cai almost to baseline. Cell acidification increased inositol trisphosphate (IP3) production, and 3,4,5-trimethoxybenzoic acid 8-(diethylamino)octyl ester, an IP3 antagonist, partially inhibited the rise in Cai. Elevation of Cai resulted in a sustained cell alkalinization from 7.32 +/- 0.02 to 7.58 +/- 0.04. When Cai was reduced, pHi fell to 7.25 +/- 0.01. We conclude that Cai and pHi participate in a feedback loop that modulates changes in each respective parameter.
在本研究中，我们调查了大鼠培养的内髓集合管细胞中细胞pH值（pHi）与细胞钙（Cai）之间的相互关系。在研究前，将汇合的单层细胞在补充有0.1%血清的杜尔贝科改良伊格尔培养基中孵育24小时，使其静止。使用荧光探针2',7'-双（羧乙基）-5,6-羧基荧光素和fura 2测量pHi和Cai的变化。在含有110 mM Na+和1 mM Cai的无碳酸氢盐的名义培养基中，细胞酸化至pH 6.70使Cai从122±24 nM增加到243±33 nM。在无浴钙的情况下，酸化使Cai从90±7 nM增加到144±13 nM。pHi升高至7.6几乎使Cai降至基线。细胞酸化增加了肌醇三磷酸（IP3）的产生，并且IP3拮抗剂3,4,5-三甲氧基苯甲酸8-（二乙氨基）辛酯部分抑制了Cai的升高。Cai的升高导致细胞持续碱化，从7.32±0.02升高到7.58±0.04。当Cai降低时，pHi降至7.25±0.01。我们得出结论，Cai和pHi参与了一个反馈回路，该回路调节各自参数的变化。
