Diphenylamine-2-carboxylate (DPC) reduces calcium influx in a mouse mandibular cell line (ST885).
Non-selective cation channels are found in many diverse cell types and have been proposed as a potential entry path for Ca2+. ST885 cells contain large numbers of these channels which are active in the resting cell. We have used Fura-2 to monitor changes in intracellular free Ca2+ ([Ca2+]i) in response to step changes in extracellular Ca2+ ([Ca2+]o). We found that DPC, a blocker of the non-selective cation channel in these cells, caused a reduction of approximately 50% in the rate of rise in [Ca2+]i following a step increase in [Ca2+]o. Since our experiments demonstrate that this phenomenon is not due to DPC blockade of Cl- channels, the Na+/Ca2+ exchanger or cyclooxygenase, we conclude that it is attributable to a direct effect of DPC on the non-selective cation channel. It thus appears that the non-selective cation channel is a significant pathway for basal Ca2+ entry in these cells.
Poronnik
P
P
Department of Physiology, University of Sydney, New South Wales, Australia.
Cook
D I
DI
Allen
D G
DG
Young
J A
JA
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers; D002460:Cell Line; D002463:Cell Membrane Permeability; D006863:Hydrogen-Ion Concentration; D007213:Indomethacin / Q000494:pharmacology; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism*; D007474:Ion Exchange; D008334:Mandible / Q000378:metabolism; D051379:Mice; D011188:Potassium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D013463:Sulfuric Acid Esters / Q000494:pharmacology; D062367:ortho-Aminobenzoates / Q000494:pharmacology*
D002121:Calcium Channel Blockers; D007473:Ion Channels; D013463:Sulfuric Acid Esters; D062367:ortho-Aminobenzoates; C001209:fenamic acid; D012964:Sodium; C033522:methyl sulfate; D011188:Potassium; D002118:Calcium; D007213:Indomethacin