Regulation of perinatal respiration-related activity and Cl- homeostasis : searching for the factors of sudden infant death syndrome in the brain

阳离子-氯离子共转运体被认为在细胞内氯离子浓度([Cl^-]i)的调节中起关键作用，从而在神经元功能的控制中发挥重要作用。首先，我用KCC2抗体检测了发育过程中小鼠延髓中KCC2的免疫反应性。舌下神经核内KCC2的免疫活性在P0时高于P7，而迷走神经核内KCC2的免疫反应在P0时无变化。由于KCC2在延髓中与呼吸相关节律活动(RRA)相关的表达模式的发育变化尚不清楚，我记录了P0-7小鼠延髓切片制备中与呼吸相关的神经元的RRA。在此条件下，灌流含100μγ-氨基丁酸的ACSF一过性增加RRA的频率。KCC2抑制剂速尿也增加了RRA的发生频率。因此，在出生后早期，氯离子稳态可能调节运动输出的活动。

Cation-chloride cotransporters are considered to play critical roles in the regulation of intracellular chloride ion concentration ([Cl^-]_i), and hence in the control of neuronal function. First, I tested the immunoreactivity of KCC2 using KCC2 antibody in developmental mouse medulla. Immunoreactivity of KCC2 in hypoglossal nucleus at P0 was higher than that at P7, while that of vagus nerve nucleus did not change during same period. Since developmental changes in expression pattern of KCC2 associated with respiration-related rhythmic activity (RRA) in medulla are not yet well understood, I recorded RRA extracellulary from respiration-related neurons in medullary slice preparation obtained from mice of P0-7. Under these conditions, perfusion of 100μM GABA-containing ACSF transiently increased the frequency of RRA. The KCC2 inhibitor furosemide also increased the frequency of RRA. Thus Cl^- homeostasis likely regulates the activity of motor output in early postnatal stage.