Lundy Paul M, Nelson Peggy, Mi Lei, Frew Robert, Minaker Sean, Vair Cory, Sawyer Thomas W
Medical Therapy Group, Chemical Biological Defence Section, Defence R&D Canada-Suffield, Box 4000, Medicine Hat, Alberta, Canada.
Eur J Pharmacol. 2004 Mar 8;487(1-3):17-28. doi: 10.1016/j.ejphar.2004.01.010.
The ATP-P2X(7) receptor subtype and a maitotoxin-activated ion channel were studied to determine factors which identify them as separate entities in the control of a cytotolytic pore. Activation of ATP-P2X(7) receptors with 2'-3'-O-(benzylbenzyl) ATP (BzATP) or maitotoxin ion channels resulted in influx of ethidium bromide and cell death. Maitotoxin (25-250 pM)-induced ethidium bromide uptake and cell death was sensitive to extracellular Ca(2+), the ionic composition of the buffer, reduced by the calmodulin inhibitor W7, (N-(s-aminohexyl)-5-chloro-1-naphthalenesulfonamide), (10-100 microM) but unaffected by the ATP-P2X(7) receptor antagonist oxidized ATP, (adenosine 5'-triphosphate periodate oxidized sodium salt) (oATP). BzATP (10-200 microM)-induced ethidium bromide uptake and cell death were inhibited by oATP, unaffected by W7, inhibited by high ionic concentrations but only slightly dependant on external Ca(2+). These results are consistent with the existence of a pharmacological mechanism for controlling cell death consisting of an ATP-P2X(7) receptor, a maitotoxin-activated ion channel and a cytolytic pore.
