Premium
Pharmacological sensitivity of ATP release triggered by photoliberation of inositol‐1,4,5‐trisphosphate and zero extracellular calcium in brain endothelial cells
Author(s) -
Braet Katleen,
Aspeslagh Sandrine,
Vandamme Wouter,
Willecke Klaus,
Martin Patricia E. M.,
Evans W. Howard,
Leybaert Luc
Publication year - 2003
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.10365
Subject(s) - connexin , extracellular , calcium , gap junction , microbiology and biotechnology , chemistry , biophysics , ouabain , biochemistry , biology , intracellular , organic chemistry , sodium
Recently, ATP has gained much interest as an extracellular messenger involved in the communication of calcium signals between cells. The mechanism of ATP release is, however, still a matter of debate. In the present study we investigated the possible contribution of connexin hemichannels or ion channels in the release of ATP in GP8, a rat brain endothelial cell line. Release of ATP was triggered by photoactivation of InsP 3 or by reducing the extracellular calcium concentration. Both trigger protocols induced ATP release significantly above baseline. InsP 3 ‐triggered ATP release was completely blocked by α‐glycyrrhetinic acid (α‐GA), the connexin mimetic peptides gap 26 and 27, and the trivalent ions gadolinium and lanthanum. ATP release triggered by zero calcium was, in addition to these substances, also blocked by flufenamic acid (FFA), niflumic acid, and NPPB. Gap 27 selectively blocked zero calcium‐triggered ATP release in connexin‐43 transfected HeLa cells, while having no effect in wild‐type and connexin‐32 transfected cells. Of all the agents used, only α‐GA, FFA and NPPB significantly reduced gap junctional coupling. In conclusion, InsP 3 and zero calcium‐triggered ATP release show major similarities but also some differences in their sensitivity to the agents applied. It is suggested that both stimuli trigger ATP release through the same mechanism, which is connexin‐dependent, permeable in both directions, potently blocked by connexin mimetic peptides, and consistent with the opening of connexin hemichannels.J. Cell. Physiol. 197: 205–213, 2003© 2003 Wiley‐Liss, Inc.