The mitochondrial potassium cycle
Garlid, K.D. and Paucek, P. (2001) The mitochondrial potassium cycle,
IUBMB Life 52, 153-8.
The mitochondrial K+ cycle consists of influx and efflux pathways for K+ and
anions. Net movement of K+ salts across the inner membrane causes changes
of matrix volume, so regulation of the cycle is vital for maintaining the
structural integrity of the organelle. The mitochondrial K+ cycle also appears
to play important roles in cellular pathophysiology in vivo. Opening the mitochondrial
ATP-sensitive K+ channel (mitoK(ATP)) prior to ischemia protects the heart
from ischemia-reperfusion injury. MitoK(ATP) is an important player in the
cell signaling pathways for ischemic protection and also for gene transcription,
roles that appear to depend on the ability of mitoK(ATP) opening to trigger
increased mitochondrial production of reactive oxygen species. MitoK(ATP)
opening during both ischemia and reperfusion and during the high work state
is found to preserve the structure of the intermembrane space and thereby
maintains the normally low outer membrane permeability to adenine nucleotides.
This review discusses the properties of the mitochondrial K+ cycle that help
to understand the basis of these effects.