Characterisation of Ca2+ membrane permeability of renal A6 cells upon different osmotic conditions

被引:5
作者
Brochiero, E [1 ]
Ehrenfeld, J [1 ]
机构
[1] CEA, Dept Cellular & Mol Biol, URA 1855, CNRS,Lab Jean Maetz, F-06230 Villefranche Sur Mer, France
关键词
A6; cells; volume regulatory decrease; fura-2; calcium channels; intracellular stores; nifedipine; oxonol VI;
D O I
10.1159/000174253
中图分类号
Q4 [生理学];
学科分类号
071003 ;
摘要
The nature of the calcium-transporting mechanisms involved in A6 cell calcium homeostasis under iso-and hypo-osmotic conditions was investigated using fura-2 (AM) as a cell calcium indicator. Under steady-state conditions, intracellular calcium (Ca-i(2+)) was increased by Bay K8644 or by gramicidin, an ionophore which depolarises A6 cell membranes. The Ca-i(2+) increase following calcium addition (to calcium-depleted cells) or membrane depolarisation was blocked by nifedipine but not by verapamil or omega-conotoxin, indicating that the membrane calcium permeability may be mediated by voltage-dependent and dihydropyridine-sensitive calcium channels. Ca-i(2+) could also be increased by a hypo-osmotic shock having a linear relationship with the osmolarity change. This osmotically induced Ca-i(2+) increase had an extracellular origin since it was absent when cells were suspended in a calcium-free medium and it was not affected by thapsigargin or TMB-8 application. In addition, it was inhibited by the calcium channel inhibitor, nifedipine. Furthermore, under hypo-osmotic conditions, an additional Ca-i(2+) increase, sensitive to nifedipine, was measured when cells were depolarised by gramicidin or K-gluconate addition. It is proposed that the hypo-osmotically induced cell calcium increase implies the activation of voltage-dependent and nifedipine-sensitive calcium channels, presenting the same pharmacological characteristics as those involved in cell calcium homeostasis under iso-osmotic conditions. The initial Ca-i(2+) increase was transient and stabilised to a value nevertheless higher than the iso-osmotic level; this secondary and incomplete regulatory phase did not occur in the presence of thapsigargin or TMB-8, thus providing evidence of intracellular calcium storage.
引用
收藏
页码:381 / 390
页数:10
相关论文
共 37 条
  • [1] BECK JS, 1991, AM J PHYSIOL, V260, pC861
  • [2] INVOLVEMENT AND SOURCE OF CALCIUM IN VOLUME REGULATORY DECREASE OF COLLAPSED PROXIMAL CONVOLUTED TUBULE
    BRETON, S
    BECK, JS
    CARDINAL, J
    GIEBISCH, G
    LAPRADE, R
    [J]. AMERICAN JOURNAL OF PHYSIOLOGY, 1992, 263 (04): : F656 - F664
  • [3] NA/CA EXCHANGE IN THE BASOLATERAL MEMBRANE OF THE A6 CELL MONOLAYER - ROLE IN CA-I HOMEOSTASIS
    BROCHIERO, E
    RASCHI, C
    EHRENFELD, J
    [J]. PFLUGERS ARCHIV-EUROPEAN JOURNAL OF PHYSIOLOGY, 1995, 430 (01): : 105 - 114
  • [4] BASOLATERAL MEMBRANE CHLORIDE PERMEABILITY OF A6 CELLS - IMPLICATION IN CELL-VOLUME REGULATION
    BROCHIERO, E
    BANDERALI, U
    LINDENTHAL, S
    RASCHI, C
    EHRENFELD, J
    [J]. PFLUGERS ARCHIV-EUROPEAN JOURNAL OF PHYSIOLOGY, 1995, 431 (01): : 32 - 45
  • [5] BASOLATERAL MEMBRANE POTASSIUM CONDUCTANCE OF A6-CELLS
    BROILLET, MC
    HORISBERGER, JD
    [J]. JOURNAL OF MEMBRANE BIOLOGY, 1991, 124 (01) : 1 - 12
  • [6] MEDIATION OF CELL-VOLUME REGULATION BY CA-2+ INFLUX THROUGH STRETCH-ACTIVATED CHANNELS
    CHRISTENSEN, O
    [J]. NATURE, 1987, 330 (6143) : 66 - 68
  • [7] EHRENFELD J, 1994, J MEMBRANE BIOL, V138, P181
  • [8] GRYNKIEWICZ G, 1985, J BIOL CHEM, V260, P3440
  • [9] TOAD URINARY-BLADDER EPITHELIAL-CELLS IN CULTURE - MAINTENANCE OF EPITHELIAL STRUCTURE, SODIUM-TRANSPORT, AND RESPONSE TO HORMONES
    HANDLER, JS
    STEELE, RE
    SAHIB, MK
    WADE, JB
    PRESTON, AS
    LAWSON, NL
    JOHNSON, JP
    [J]. PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 1979, 76 (08) : 4151 - 4155
  • [10] INVOLVEMENT OF CA-2+-INDUCED CA-2+ RELEASE IN THE VOLUME REGULATION OF HUMAN EPITHELIAL-CELLS EXPOSED TO A HYPOTONIC MEDIUM
    HAZAMA, A
    OKADA, Y
    [J]. BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS, 1990, 167 (01) : 287 - 293