爪蟾胚胎脊髓胆碱能神经元上两类非去极化激活的钙通道

用膜片箝方法,在标定的爪蟾胚胎脊髓胆碱能神经细胞膜上记录钙离子单通道电流。结果显示,在静息膜电位时钙通道即有开放活动。根据通道的电导及动力学等特性,我们将其分为两种类型:NS 型钙通道,斜率电导7.5pS,静息膜电位时平均开放时间0.58ms,其活动受牵张膜片的影响;NL 型钙通道,斜率电导16.7pS,静息膜电位时二级平均开放时间分别是2ms 和19.3ms。鉴于它们在膜静息以及负电位相的显著活动,我们推测这两类钙通道可能参与神经元静息膜电位时钙依赖的细胞活动过程。

TWO TYPES OF NONDEPOLARIZING-ACTIVATED CALCIUM CHANNELS ON THE SPINAL CHOLINERGIC NEURONS FROM EMBRYONIC XENOPUS LAEVIS

Single calcium channel current was studied on the identified spinal cholin-crgic neurons from embryonic Xenopus laevis with patch clamp method.The resultsindicate that some calcium channels show opening activity at resting membranepotential.According to the characteristics of conductance and kinetics of suchchannels,they could be divided into two types:a stretch sensitive Type-NS witha slope conductance of 7.5 pS(mean open time 0.58 ms at resting membranepotential)and a Type-NL with a slope conductance of 16.7 pS(and two openingtimes of 2ms and 19.3 ms).Both types of channel are predominantly active atresting potential and negative membrane phases.It is suggested that they maybe involved in the calcium-dependent neuronal events at resting state.