* To whom correspondence should be addressed.
Received November 11, 2009; Revision received April 26, 2010
The influence of the K+ATP-channel opener diazoxide on the K+ cycle and oxygen consumption has been studied in rat liver mitochondria. It was found that diazoxide activates the K+ATP-channel in the range of nanomolar concentrations (50-300 nM, K1/2 ~ 140 nM), which results in activation of K+/H+ exchange in mitochondria. The latter, in turn, accelerates mitochondrial respiration in respiratory state 2. The contribution of K+ATP-channel to the mitochondrial potassium cycle was estimated using the selective K+ATP-channel blocker glibenclamide. The data show that the relative contribution of K+ATP-channel in the potassium cycle of mitochondria is variable and increases only with the decrease in the ATP-independent component of K+ uptake. Possible mechanisms underlying the observed phenomena are discussed. The experimental results more fully elucidate the role of K+ATP-channel in the regulation of mitochondrial functions, especially under pathological conditions accompanied by impairment of the mitochondrial energy state.
KEY WORDS: ATP-dependent K+-channel, mitochondria, potassium, transport, diazoxide, oxygen consumption, potassium cycle