CaV2.3 calcium channels control second-phase insulin release
J. Clin. Invest. Xingjun Jing, et al. 115:146 doi:10.1172/JCI22518 [
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Figure 1Whole-cell Ca
2+ currents in islet cells from WT and
CaV2.3–/– mice. (
A) Whole-cell Ca
2+ currents (
i) evoked by a 300-ms voltage-clamp depolarization (
V) in WT
CaV2.3+/+ (black) and
CaV2.3–/– (gray) β cells. β cells were identified by exhibiting half-maximal Na
+ channel inactivation at membrane potentials (
V) lower than –100 mV (half-maximal inactivation at –102 mV; inset). (
B) Average integrated current-voltage (
Q-V) relationships. Data are mean values ± SEM in 10 WT (filled circles) and 10
CaV2.3–/– (shaded circles) β cells. *
P < 0.05. (
C) Whole-cell Ca
2+ currents were recorded as in
A, but using
CaV2.3–/– β cells. The recordings were made under control conditions (lower gray line) in the presence of R-type Ca
2+ channel blocker SNX482 (100 nM; black line) and after addition of L-type Ca
2+ channel inhibitor isradipine (isr) (2 μM; upper gray line). (
D) Average
Q-V relationships representing mean values ± SEM in 4
CaV2.3–/– β cells under control conditions (shaded circles), in the presence of SNX482 (filled circles), and after addition of isradipine (open circles). *
P < 0.05, **
P < 0.01, control versus SNX482 plus isradipine. (
E) Whole-cell Ca
2+ currents were recorded as in
A, but in α cells identified by Na
+ channel inactivation at membrane potentials greater than –100 mV (half-maximal inactivation at –49 mV; inset). (
F)
Q-
V relationships in α cells. Data represent average values ± SEM in 8 WT (filled circles) and 4
CaV2.3–/– (shaded circles) α cells. pC, picocoulombs.