Fig. 6
AdipoR1 selectively enhances recombinant Cav3.2 channel currents. A Determination of mRNAs of classic PKC isoforms (PKCα, PKCβ1, PKCβ2 and PKCγ) in HEK293 cells. No signal was detected in the reactions without RT (− RT). B Protein abundance of adipoR1 in HEK293 cells transiently transfected with adipoR1 cDNA. GAPDH served as an equal loading control. Representative blots of at least 3 independent experiments are shown. C Representative traces revealing the effect of adiponectin (100 nM) on recombinant Cav3.1, Cav3.2 and Cav3.3 T-type channel currents. IT was elicited by a step-pulse depolarization from a holding potential of -90 mV to -30 mV. D Bar graph revealing the effect of adiponectin (100 nM) on Cav3.1 (n = 9 cells), Cav3.2 (n = 12 cells) or Cav3.3 (n = 10 cells) channel currents indicated in Panel D. ***p < 0.001 (vs. control), paired t test. E, Dose‒response curves of adiponectin on Cav3.2 channel currents. The solid line represents the best fit with the Hill equation. In brackets is the number of cells recorded at each concentration of adiponectin. F-G Representative traces (left) and bar graph (right) revealing the effect of adiponectin (100 nM) on the current–voltage curve (n = 12 cells). Currents were recorded by step pulse depolarizations to potentials ranging from -80 mV to 0 mV in 10-mV increments. *p < 0.05 (vs. control), one-way ANOVA. H-I Adiponectin at 100 nM did not significantly alter the voltage-dependent activation profile of IT (n = 10 cells) but shifted the steady-state inactivation curve in the depolarizing direction (n = 11 cells). J Bar chart summarizing the effect of adiponectin on the V50 of the activation or inactivation curve. *p < 0.05 (vs. control), unpaired t test. K Bar graph revealing the effect of adiponectin (100 nM) on recombinant Cav3.2 channel currents in cells dialyzed with PKCβ1-IP (10 μM, n = 7 cells)