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Functional Characterisation of the Volume‐Sensitive Anion Channel in Rat Pancreatic β‐Cells
Author(s) -
Best L.,
Speake T.,
Brown P. D.
Publication year - 2001
Publication title -
experimental physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0958-0670
DOI - 10.1113/eph8602118
Subject(s) - extracellular , forskolin , patch clamp , chemistry , ion channel , protein kinase a , biophysics , divalent , protein kinase c , biochemistry , kinase , microbiology and biotechnology , medicine , biology , receptor , organic chemistry
The whole‐cell and perforated patch configurations of the patch‐clamp technique were used to characterise the volume‐sensitive anion channel in rat pancreatic β‐cells. The channel showed high permeability ( P ) relative to Cl − to extracellular monovalent organic anions ( P SCN / P Cll = 1.73, P acetate / P Cll = 0.39, P lactate / P Cll = 0.38, P acetoacetate / P Cll = 0.32, P glutamate / P Cll = 0.28) but was less permeable to the divalent anion malate ( P malate / P Cll = 0.14). Channel activity was inhibited by a number of putative anion channel inhibitors, including extracellular ATP (10 mM), 1,9‐dideoxyforskolin (100 μM) and 4‐OH tamoxifen (10 μM). Inclusion of the catalytic subunit of protein kinase A in the pipette solution did not activate the volume‐sensitive anion channel in non‐swollen cells. Furthermore, addition of 8‐bromoadenosine 3′,5′‐cyclic monophosphate (8‐BrcAMP) or forskolin failed to activate the channel in intact cells under perforated patch conditions. Addition of phorbol 12,13‐dibutyrate (200 nM), either before or after cell swelling, also failed to affect channel activation. Our findings do not support the suggestion that the volume‐sensitive anion channel in pancreatic β‐cells can be activated by protein kinase A. Furthermore, the β‐cell channel does not appear to be subject to regulation via protein kinase C.