抄録
GABA, a major inhibitory neurotransmitter in the adult CNS, is excitatory at early developmental stages due to the elevated intracellular Cl− concentration ([Cl−]i). This functional switch is primarily attributable to the K+-Cl− cotransporter KCC2, the expression of which is developmentally regulated in neurons. Previously we reported that KCC2 interacts with brain-type creatine kinase (CKB). To elucidate the functional significance of this interaction, HEK293 cells were transfected with KCC2 and glycine receptor α2 subunit, and gramicidin-perforated patch-clamp recordings were performed to measure the glycine reversal potential (Egly), giving an estimate of [Cl−]i. KCC2-expressing cells displayed the expected changes in Egly following alterations in the extracellular K+ concentration ([K+]o) or administration of an inhibitor of KCCs, suggesting that the KCC2 function was being properly assessed. When added into KCC2-expressing cells, dominant-negative CKB induced a depolarizing shift in Egly and reduced the hyperpolarizing shift in Egly seen in response to a lowering of [K+]o) compared to wild-type CKB. Moreover, 2,4-dinitrofluorobenzene (DNFB), an inhibitor of CKs, shifted Egly in the depolarizing direction. In primary cortical neurons expressing CKB, the GABA reversal potential was also shifted in the depolarizing direction by DNFB. Our findings suggest that in the cellular microenvironment, CKB activates the KCC2 function. [J Physiol Sci. 2006;56 Suppl:S124]
