| The Na+-K+-Cl− cotransporter 1 (NKCC1) is a ubiquitous protein that is important for regulation of cell volume as well as Na+ secretion and absorption. In the past decade, there have been reports that the NKCC is activated in hypoxia (Kawai et al., 1996) and its inhibitor prevents cell damage in ischemic heart and liver models (Fiegen, et al., 1997, Ramasay et al., 2001). More recent studies show that the NKCC inhibitor, bumetanide, prevents cellular damage in a model of focal cerebral ischemia (Yan et al., 2001). Until now, there has been no investigation of mechanisms underlying NKCC1-mediated damage in an in vitro model of neuronal ischemia.; The aim of this research has been to investigate the role of NKCC1 in excitotoxicity and ischemia using cultured rodent neurons. We have found that the NKCC1 inhibitor, bumetanide, reduces cell mortality in rat neuronal cultures exposed to either glutamate, NMDA, or oxygen glucose deprivation. This reduction in mortality is dependent on early application of bumetanide and is not observed in neurons that have yet to express NMDA receptors. Furthermore, bumetanide also reduces cell swelling and both Na+ and Cl− accumulations caused by NMDA treatment.; The contribution of NKCC1 to excitotoxicity has been confirmed in a transgenic mouse model. Neurons lacking NKCC1 experienced less cell death following oxygen glucose deprivation when compared to wild-type neurons. NKCC1−/− neurons also showed less accumulation of intracellular Na + compared to wild-type neurons.; In summary, this research expands upon the neuroprotective effects of NKCC1 observed using in vivo rodent models. Our observations clearly show that NKCC1 can contribute to excitotoxicity in rodent neuronal cultures. This work demonstrates NKCC1's potential as a molecular target for the treatment of stroke. |
