FIGURE 7.
Endosomal trafficking and PKC sensitivity of KATP channels in INS1e model β-cells. A, effect of PKC activation on the intracellular distribution of endocytosed KATP channels. Following internalization of anti-HA antibodies, the cells were stained as in Fig. 5. In each panel, the larger images represent a merger of smaller images of cells stained for HA-Kir6.2 and the indicated marker protein. B, PKC activation with PMA increases intracellular accumulation of surface channels. INS1e cells were transfected with HA-Kir6.2, and internalization of anti-HA antibodies was performed in the presence of indicated drugs as described for Fig. 3A. The scale bars equal 10 μm. C and D, PKC activation with PMA reduces channel current density. C, mean current-voltage relationships from INS1e cells treated for 2 h with either vehicle (DMSO, 0.1%; ■) or PMA (100 nm; □) (n = 3 in each group). D, the tolbutamide-sensitive conductance, calculated from the data in C. The data are the means ± S.E. * denotes statistical significance at the p < 0.05 level.