| 12695985 |
Shin DS, Buck LT: Effect of anoxia and pharmacological anoxia on whole-cell NMDA receptor currents in cortical neurons from the western painted turtle. Physiol Biochem Zool. 2003 Jan-Feb;76(1):41-51.
The mammalian brain undergoes rapid cell death during anoxia that is characterized by uncontrolled Ca (2+) entry via N-methyl-D-aspartate receptors (NMDARs). In contrast, the western painted turtle is extremely anoxia tolerant and maintains close-to-normal [Ca (2+)](i) during periods of anoxia lasting from days to months. A plausible mechanism of anoxic survival in turtle neurons is the regulation of NMDARs to prevent excitotoxic Ca (2+) injury. However, studies using metabolic inhibitors such as cyanide (NaCN) as a convenient method to induce anoxia may not represent a true anoxic stress. This study was undertaken to determine whether turtle cortical neuron whole-cell NMDAR currents respond similarly to true anoxia with N (2) and to NaCN-induced anoxia. Whole-cell NMDAR currents were measured during a control N (2)-induced anoxic transition and a control NaCN-induced transition. During anoxia with N (2) normalized, NMDAR currents decreased to 35.3%+/-10.8% of control values. Two different NMDAR current responses were observed during NaCN-induced anoxia: one resulted in a 172%+/-51% increase in NMDAR currents, and the other was a decrease to 48%+/-14% of control. When responses were correlated to the two major neuronal subtypes under study, we found that stellate neurons responded to NaCN treatment with a decrease in NMDAR current, while pyramidal neurons exhibited both increases and decreases. Our results show that whole-cell NMDAR currents respond differently to NaCN-induced anoxia than to the more physiologically relevant anoxia with N (2). |
2(0,0,0,2) |