1. @entity27402 channels are activated by extracellular @entity855 . Despite being commonly described as non-desensitizing, @entity27402 receptors do desensitize or inactivate. In the unspliced, 472 @entity535 isoform of the @entity27402 receptor, inactivation required membrane disruption and the presence of extracellular @entity141 . 2. The ability to inactivate whole-cell currents developed slowly after breaking in. In contrast, currents from excised patches exhibited rapid (approximately 100 ms) inactivation with a dependence on extracellular @entity141 , @entity855 and voltage. 3. The inactivation rate increased with the fourth power of [ @entity141 ] suggesting that the functional channel may be a tetramer. @entity141 had both a higher affinity and a larger Hill coefficient for inactivation than @entity1025 , @entity8594 or @entity3281 . Trivalent cations at concentrations up to the solubility product of @entity855 had no effect. The change in apparent co-operativity with ionic species suggests the presence of experimentally unresolved ligand-insensitive kinetic steps. 4. Based on the weak voltage dependence of inactivation and the lack of effect of intracellular @entity141 buffers, the @entity141 -binding sites are probably located near the extracellular surface of the membrane. 5. The recovery from inactivation was slow, with a time constant of approximately 7 min. 6. @entity141 -sensitive inactivation only appeared when the membrane was disrupted in some manner. Treatment with actin and microtubule reagents did not induce inactivation, suggesting that an intact cytoskeleton is not necessary. 7. Inactivation rates observed in different patch configurations suggest that the induction of @entity141 -dependent inactivation was due to the loss of a diffusible cofactor located in the membrane or the cytoplasm.

Inactivation of XXXX purinoceptors by divalent cations.

@entity1025 :: ('CHEBI:18420', 'Chemical') :: ['Mg2+'] @entity535 :: ('CHEBI:33704', 'Chemical') :: ['amino acid'] @entity141 :: ('CHEBI:29108', 'Chemical') :: ['Ca2+'] @entity3281 :: ('CHEBI:29035', 'Chemical') :: ['Mn2+'] @entity8594 :: ('MESH:C080430', 'Chemical') :: ['Ba2+'] @entity27402 :: ('22953', 'Gene') :: ['P2X2'] @entity855 :: ('MESH:D000255', 'Chemical') :: ['ATP']
@entity27402 :: (22953,Gene) :: ['P2X2']
