Ionic control mechanisms of @entity19 pancreatic beta-cell action potentials ("spikes"), in response to @entity413 , were studied by measuring membrane potentials with intracellular microelectrodes. The curve relating the peaks of the spikes to the log of the external @entity460 concentration above 10 mM has a slope of 25 mV/10-fold increase of @entity141 . This approaches the value predicted by the Nernst equation for a pure @entity141 electrode. Increasing the external [ @entity141 ]o from 0 to 42.5 mM caused an increase in rates of spike depolarization and repolarization. Lowering [ @entity141 ]o or applying @entity141 conductance blockers, including @entity515 (1.25 mM), @entity3281 (2mM), and D-600 (2 X 10(-4) M), caused a decrease in rates of spikes depolarization and repolarization, with an increase of [ @entity141 ]o reversing this effect. Higher concentrations of these @entity141 -conductance blockers eliminated the spike activity. @entity5126 at a high concentration (10(-3) M) blocked spike repolarization. @entity5128 ( @entity1041 , 25 mM) increased spike amplitude and duration. Therefore, it is concluded that @entity141 entry during the spike affects @entity972 permeability, which is inhibited by @entity1041 . Also, there is a competitive binding between @entity515 , @entity3281 , @entity1025 , and @entity141 , the charge carrier. These cations may have an additional action of substituting for @entity141 to "stabilize" the membrane.

XXXX action potentials and @entity972 permeability activation in pancreatic beta-cells.

@entity1041 :: ('MESH:D013662', 'Chemical') :: ['TEA'] @entity1025 :: ('CHEBI:18420', 'Chemical') :: ['Mg2+'] @entity19 :: ('10090', 'Species') :: ['mouse'] @entity3281 :: ('CHEBI:29035', 'Chemical') :: ['Mn2+'] @entity5128 :: ('MESH:D019789', 'Chemical') :: ['Tetraethylammonium'] @entity515 :: ('CHEBI:29334', 'Chemical') :: ['Co2+'] @entity5126 :: ('MESH:D011802', 'Chemical') :: ['Quinidine'] @entity460 :: ('MESH:D002118', 'Chemical') :: ['calcium'] @entity972 :: ('MESH:D011188', 'Chemical') :: ['potassium'] @entity141 :: ('CHEBI:29108', 'Chemical') :: ['Ca2+'] @entity413 :: ('MESH:D005947', 'Chemical') :: ['glucose']
@entity460 :: (MESH:D002118,Chemical) :: ['Calcium']
