Glibenclamide Decreases ATP-Induced Intracellular Calcium Transient Elevation via Inhibiting Reactive Oxygen Species and Mitochondrial Activity in Macrophages

Increasing evidence has revealed that glibenclamide has a wide range of anti-inflammatory effects. However, it is unclear whether glibenclamide can affect the resting and adenosine triphosphate (ATP)-induced intracellular calcium ([Ca(2+)]i) handling in Raw 264.7 macrophages. In the present study, [Ca(2+)]i transient, reactive oxygen species (ROS) and mitochondrial activity were measured by the high-speed TILLvisION digital imaging system using the indicators of Fura 2-am, DCFDA and rhodamine-123, respectively. We found that glibenclamide, pinacidil and other unselective K(+) channel blockers had no effect on the resting [Ca(2+)]i of Raw 264.7 cells. Extracellular ATP (100 µM) induced [Ca(2+)]i transient elevation independent of extracellular Ca(2+). The transient elevation was inhibited by an ROS scavenger (tiron) and mitochondria inhibitor (rotenone). Glibenclamide and 5-hydroxydecanoate (5-HD) also decreased ATP-induced [Ca(2+)]i transient elevation, but pinacidil and other unselective K(+) channel blockers had no effect. Glibenclamide also decreased the peak of [Ca(2+)]i transient induced by extracellular thapsigargin (Tg, 1 µM). Furthermore, glibenclamide decreased intracellular ROS and mitochondrial activity. When pretreated with tiron and rotenone, glibenclamide could not decrease ATP, and Tg induced maximal [Ca(2+)]i transient further. We conclude that glibenclamide may inhibit ATP-induced [Ca(2+)]i transient elevation by blocking mitochondria KATP channels, resulting in decreased ROS generation and mitochondrial activity in Raw 264.7 macrophages.