Research Article

Potentiation of Calcium Influx and Insulin Secretion in Pancreatic Beta Cell by the Specific TREK-1 Blocker Spadin

Figure 4

Effects of SPA on cytosolic calcium concentrations. Cytosolic calcium variations were measured using the Fura-2AM in the mouse MIN6-B1 β-cell line. Fura2-AM absorbance ratio (340/380) was given for the time point with the maximal signal. (a) At low glucose concentration (5 mM), SPA (10−7 M) induced a significant cytosolic calcium rise (, ) that did not return to basal level after washing out (). (b) Comparing SPA and ex4 effects, controls were performed using either KCl (25 mM) or glucose (20 mM) (). (c) Preincubation of MIN6-B1 cells with 5 mM 8Br-cAMP did not prevent the stimulating effect of SPA on calcium rise (). (d) When MIN6-B1 cells were preincubated with 50 mM 8Br-cAMP, SPA was not able to increase intracellular calcium (). (e) Preincubation of MIN6-B1 cells in the presence of 1 μM H89 significantly inhibited the ex4 effect but not that of SPA (). indicates the number of responding cells in each of three experiments. Results are expressed as mean ± SEM; , , and ns: nonsignificant.
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