TY - JOUR
T1 - Intracellular cAMP potentiates voltage-dependent activation of L-type Ca2+ channels in rat islet β-cells
AU - Kanno, Takahiro
AU - Suga, Sechiko
AU - Wu, Jie
AU - Kimura, Masao
AU - Wakui, Makoto
PY - 1998
Y1 - 1998
N2 - 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( 1/4 )), 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-cAM, 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.
AB - 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( 1/4 )), 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-cAM, 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.
KW - Ca channel
KW - Cyclic AMP
KW - Islet β-cells
KW - Patch-clamp
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U2 - 10.1007/s004240050556
DO - 10.1007/s004240050556
M3 - Article
C2 - 9446708
AN - SCOPUS:0031884567
VL - 435
SP - 578
EP - 580
JO - Pflugers Archiv fur die gesamte Physiologie des Menschen und der Tiere
JF - Pflugers Archiv fur die gesamte Physiologie des Menschen und der Tiere
SN - 0031-6768
IS - 4
ER -