Glibenclamide and quinine differentially modulate the intercellular synchronization of glucose-induced Ca2+ oscillations.

(A) During stimulation by 20 mM glucose in the presence of 15 mM TEA, MIN6 cells exposed for 24 h to 10 µM glibenclamide showed increased proportion of synchronous cells (gray bars) compared to control, but decreased proportions of asynchronous (white bars) and silent cells (black bars); (B) Under the same conditions, MIN6 cells exposed for 24 h to 10 µM quinine, showed a reduced proportion of synchronous cells (gray bars). Bars show means + SE values of three independent experiments. *p<0.05 versus values of WT MIN6 cells; (C) The synchrony index of WT MIN6 cells, as evaluated using a NIPKOW confocal microscope, was about 0.6. This value was decreased in AS MIN6 cells, and increased after exposure of the cells to glibenclamide; (D) Similar values of synchrony index data were semi-automatically calculated, in the same cell types, using an ImageXpress microscope. Data are means + SE of seven clusters measured for each condition in C, and 87 clusters measured for each condition in D. *p<0.05, **p<0.01 and ***p<0.001 versus values of WT MIN6 cells.