Evidences for an ATP-sensitive potassium channel (KATP) in muscle and fat body mitochondria of insect

• Mitochondrial potassium channels, mitoKATP are present in insect fat body and muscle.
• MitoKATP decrease free radical production in insect mitochondria.
• Insect mitoKATP are sensitive to potassium channel activators (KCOs) and inhibitors.
• MitoKATP of insect exhibit properties similar to mitoKATP in mammals.

In the present study, we describe the existence of mitochondrial ATP-dependent K+ channel (mitoKATP) in two different insect tissues, fat body and muscle of cockroach Gromphadorhina coquereliana. We found that pharmacological substances known to modulate potassium channel activity influenced mitochondrial resting respiration. In isolated mitochondria oxygen consumption increased by about 13% in the presence of potassium channel openers (KCOs) such as diazoxide and pinacidil. The opening of mitoKATP was reversed by glibenclamide (potassium channel blocker) and 1 mM ATP. Immunological studies with antibodies raised against the Kir6.1 and SUR1 subunits of the mammalian ATP-sensitive potassium channel, indicated the existence of mitoKATP in insect mitochondria. MitoKATP activation by KCOs resulted in a decrease in superoxide anion production, suggesting that protection against mitochondrial oxidative stress may be a physiological role of mitochondrial ATP-sensitive potassium channel in insects.

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