Investigation of the inhibitory effects of the benzodiazepine derivative, 5-BDBD on P2X4 purinergic receptors by two complementary methods.
Cell Physiol Biochem 2013;
32:11-24. [PMID:
23867750 DOI:
10.1159/000350119]
[Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/14/2013] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS
ATP-gated P2X4 purinergic receptors (P2X4Rs) are cation channels with important roles in diverse cell types. To date, lack of specific inhibitors has hampered investigations on P2X4Rs. Recently, the benzodiazepine derivative, 5-BDBD has been proposed to selectively inhibit P2X4Rs. However, limited evidences are currently available on its inhibitory properties. Thus, we aimed to characterize the inhibitory effects of 5-BDBD on recombinant human P2X4Rs.
METHODS
We investigated ATP-induced intracellular Ca(2+) signals and whole cell ion currents in HEK 293 cells that were either transiently or stably transfected with hP2X4Rs.
RESULTS
Our data show that ATP (< 1 μM) stimulates P2X4R-mediated Ca(2+) influx while endogenously expressed P2Y receptors are not activated to any significant extent. Both 5-BDBD and TNP-ATP inhibit ATP-induced Ca(2+) signals and inward ion currents in a concentration-dependent manner. Application of two different concentrations of 5-BDBD causes a rightward shift in ATP dose-response curve. Since the magnitude of maximal stimulation does not change, these data suggest that 5-BDBD may competitively inhibit the P2X4Rs.
CONCLUSIONS
Our results demonstrate that application of submicromolar ATP concentrations allows reliable assessment of recombinant P2XR functions in HEK 293 cells. Furthermore, 5-BDBD and TNP-ATP have similar inhibitory potencies on the P2X4Rs although their mechanisms of actions are different.
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