Schauf C L, Bullock J O
Biophys J. 1980 May;30(2):295-305. doi: 10.1016/S0006-3495(80)85095-8.
Careful examination of effects of solvent substitution on excitable membranes offers the theoretical possibility of identifying those aspects of the gating and translocation processes which are associated with significant changes in solvent order. Such information can then be used to develop or modify moire detailed models. We have examined the effects of heavy water substitution in Cs+-and K+-dialyzed Myxicola giant axons. At temperatures of 4-6 degrees C, the rates of Na+, K+, and Na+ inactivation during a maintained depolarization were all showed by approximately 50% in the presence of D2O. In contrast, the effects of solvent substitution on the time-course of prepulse inactivation and reactivation were much larger, with slowing averaging 160%. Studies at higher temperatures yielded Q10's for Na+ activation and K+ activation which were essentially comparable (0.72) and slightly but significantly smaller than that for inactivation during a maintained depolarization (0.84). In contrast, the Q10 for the D2O effect on prepulse inactivation was approximately 0.48. Heavy water substitution decrease Gk to a significantly greater extent than G(Na), while the decrease in the conductance of the Na+ channel caused by D2O was independent of whether the current-carrying species was Na+ or Li+. Sodium channel selectivity to the alkali metal cations and NH4+ was not changed by D2O substitution.
仔细研究溶剂替代对可兴奋膜的影响，为识别门控和转运过程中与溶剂有序性显著变化相关的那些方面提供了理论可能性。然后，这些信息可用于开发或修改更详细的模型。我们研究了重水替代对用Cs⁺和K⁺透析的黏液巨轴突的影响。在4至6摄氏度的温度下，在存在重水的情况下，持续去极化期间Na⁺、K⁺和Na⁺失活的速率均降低了约50%。相比之下，溶剂替代对预脉冲失活和再激活时间进程的影响要大得多，平均减慢160%。在较高温度下的研究得出，Na⁺激活和K⁺激活的Q₁₀基本相当（0.72），且略低于但显著低于持续去极化期间失活的Q₁₀（0.84）。相比之下，重水对预脉冲失活影响的Q₁₀约为0.48。重水替代使Gk降低的程度明显大于G(Na)，而重水引起的Na⁺通道电导降低与载流离子是Na⁺还是Li⁺无关。重水替代未改变钠通道对碱金属阳离子和NH₄⁺ 的选择性。
