Abstract
Intracellular cAMP-dependent modulation of L-type Ca2+ channel activation in cultured rat islet β-cells has been investigated using the patch-clamp whole-cell current recording mode. The L-type voltage-dependent Ca2+ current (I Ca) showed a fast activation followed by a slow inactivation, and was sensitive to Ca2+ channel blockers, for example nifedipine. Application of a cAMP analogue, dibutyryl cyclic AMP (db-cAMP), increased the magnitude of the peak I Ca in a concentration-dependent manner. Values of the half-activation potentials (V 1/2), taken from activation curves for I Ca, were –16.7 ± 1.8 and –21.9 ± 3.4 mV (P < 0.05) before and after application of db-cAMP, respectively, with no change of the slope factor (k) or the reversal potential. Pretreatment with a specific protein kinase A antagonist, Rp-cAMP, prevented the potentiating effect of db-cAMP. These results indicate that in rat islet β-cells, phosphorylation of cAMP-dependent kinase potentiates the voltage-dependent activation of L-type Ca2+ channels.
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Received: 9 September 1997 / Received after revision: 19 November 1997 / Accepted: 21 November 1997
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Kanno, T., Suga, S., Wu, J. et al. Intracellular cAMP potentiates voltage-dependent activation of L-type Ca2+ channels in rat islet β-cells. Pflügers Arch 435, 578–580 (1998). https://doi.org/10.1007/s004240050556
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DOI: https://doi.org/10.1007/s004240050556