Yoshida T, Taga K, Okabayashi H, Kamaya H, Ueda I
Department of Applied Chemistry, Nagoya Institute of Technology, Japan.
Biochim Biophys Acta. 1989 Sep 4;984(2):253-6. doi: 10.1016/0005-2736(89)90224-1.
The effects of phase transition on the surface capacitance and conductance parallel to dipalmitoyl- (DPPC) and dimyristoyl-phosphatidylcholine (DMPC) membranes were studied by impedance dispersion. The phospholipid aggregates were embedded into pores of a polycarbonate filter and the impedance dispersions were measured at a frequency range from 30 Hz to 1.0 MHz. When the frequency was below 120 kHz, the capacitance showed a peak at the pretransition temperature and a steep rise at the main-transition temperature. In this system, the observed capacitance consists of frequency-dependent and -independent parts. The frequency-dependent part is a surface phenomenon and arises from the lateral motion of counterions at the membrane/water interface. The frequency-independent part represents mainly the properties of the bulk lipid phase. Addition of halothane decreased the total capacitance of the DPPC aggregates at the low frequency range to 1/2 to 1/8 of the control depending upon the temperature. The surface component was solely responsible for this capacitance decrease, because the non-surface component was slightly increased instead. The data suggest that halothane inhibited the lateral ionic flow parallel to the interface.
通过阻抗色散研究了相变对与二棕榈酰磷脂酰胆碱（DPPC）和二肉豆蔻酰磷脂酰胆碱（DMPC）膜平行的表面电容和电导的影响。将磷脂聚集体嵌入聚碳酸酯滤膜的孔中，并在30Hz至1.0MHz的频率范围内测量阻抗色散。当频率低于120kHz时，电容在预转变温度处出现峰值，并在主转变温度处急剧上升。在该系统中，观察到的电容由频率相关和频率无关的部分组成。频率相关部分是一种表面现象，由膜/水界面处反离子的横向运动引起。频率无关部分主要代表本体脂质相的性质。根据温度的不同，添加氟烷可使DPPC聚集体在低频范围内的总电容降低至对照的1/2至1/8。表面成分是这种电容降低的唯一原因，因为非表面成分反而略有增加。数据表明，氟烷抑制了与界面平行的横向离子流。
