Effect of Glucose on [Ca²⁺]_c in MIN6 Cells.

<p>A: M-Cameleon-nano15-expressing cells were incubated in HBSS containing 2.8 mM glucose. The cells were then stimulated by 25 mM glucose as indicated by the arrow and changes in [Ca^<b>2+</b>]_c were monitored. The result is a representative of those obtained in more than 300 cells from 10 experiments. B: Cells were treated as indicated above and a typical trace without the initial rapid peak is presented. The result is a representative of those obtained in more than 200 cells from 10 experiments. C: AUC of the oscillatory elevation of [Ca^<b>2+</b>]_c (between 5 and 15 min) was calculated in A and B. Values are the mean ± SE of ten experiments. *: P< 0.01 vs ‘with rapid peak’. D: PM-Cameleon-nano15-expressing cells were also loaded with fura-2 and stimulated by 25 mM glucose as indicated by the arrow. Changes in [Ca^<b>2+</b>]_c were monitored by using PM-Cameleon-nano15. E, F: PM-Cameleon-nano15-expressing cells were incubated in HBSS containing 2.8 mM glucose. Then cells were stimulated by 8.3 mM (E) or 16.7 mM (F) glucose and changes in [Ca^<b>2+</b>]_c were monitored. Results obtained in cells presenting a rapid peak of [Ca^<b>2+</b>]_c were shown. The results are the mean ± SE for 10 determinations. G, H: PM-Cameleon-nano15-expressing cells were stimulated by various concentrations of glucose as shown in A, E and F and the peak height of the rapid peak (G) and AUC from 5 to 10 min were measured. Values are the mean ± SE for 10 determinations.