The role of the ATP-sensitive potassium channel in the activation of the K+ cycle in rat liver mitochondria |
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Authors: | O S Gorbacheva D A Moshkov N I Venediktova G D Mironova |
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Affiliation: | 1. Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, ul. Institutskaya, 3, Pushchino, Moscow oblast, 142290, Russia 2. Pushchino State Institute of Natural Science, prospekt Nauki, 3, Pushchino, Moscow oblast, 142290, Russia
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Abstract: | It is known that the mitochondrial ATP-sensitive potassium channel (mitoKATP) plays a key role in protecting myocardium during ischemia. We have suggested that the mechanism of this protection is associated with the potassium cycle in mitochondria. In this paper, for the first time, a direct proof was obtained of the existence of a cycle of potassium ions in rat liver mitochondria that are associated with the functioning of mitoKATP. Activation of the cycle was recorded by optical density changes of mitochondrial suspension in the form of two or three swelling-contraction waves of the organelles. Using activators and inhibitors of mitoKATP we showed that a significant role in the potassium cycle belongs to the channel. It was found that in vitro sildenafil has a direct effect on mitoKATP, being its activator. The results obtained indicate that the cardioprotective effect of sildenafil observed previously is associated with the activation of mitoKATP. In order to study the structure and volume changes of mitochondria in various stages of the cycle in the presence of potassium channel modulators, the electron microscopy studies of mitochondria preparations were carried out. A correlation between the optical density decrease of mitochondrial suspension and the swelling of mitochondria was revealed. The data obtained in this study suggest participation of mitoKATP in the protection of tissues from hypoxic damage. |
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