Collin C, Papageorge A G, Sakakibara M, Huddie P L, Lowy D R, Alkon D L
National Institutes of Health, Laboratory of Molecular and Cellular Neurobiology, Bethesda, Maryland 20892.
Biophys J. 1990 Sep;58(3):785-90. doi: 10.1016/S0006-3495(90)82421-8.
Two electrode voltage clamp conditions were used to study the early effects on ionic membrane channels of the intracellularly injected proto-oncogenic form of c-Ha-ras (c-ras) and its oncogenic counterpart v-Ha-ras (v-ras). These experiments were conducted on isolated somata of identified fully differentiated neurons of the sea snail Hermissenda. 20 min after c-ras, and 10 min after v-ras intracellular injections into type B medial photoreceptors of Hermissenda, the peak amplitude of two outward potassium currents (IA and IC), across the isolated Type B soma membrane begin to decrease. These two currents have been previously isolated by differences in activation and inactivation kinetics and their response to pharmacological blockers. c- or v-ras injections did not have any effect on a voltage-dependent inward calcium current. Reduction of IA preceded that of IC. Current reductions due to c-ras, but not to v-ras injection reversed spontaneously after 40 min. The voltage dependence of the steady state inactivation of IA shifted toward more negative potentials with ras injections. Ras-mediated cell transformations therefore, could involve, perhaps as initial events, prolonged modification of membrane currents.
采用双电极电压钳制条件来研究细胞内注射原癌基因形式的c-Ha-ras（c-ras）及其致癌对应物v-Ha-ras（v-ras）对离子膜通道的早期影响。这些实验是在海蜗牛海兔已鉴定的完全分化神经元的分离胞体上进行的。在将c-ras注射到海兔B型内侧光感受器细胞内20分钟后，以及将v-ras注射到该细胞内10分钟后，分离的B型胞体膜上两种外向钾电流（IA和IC）的峰值幅度开始下降。这两种电流先前已通过激活和失活动力学的差异及其对药理阻断剂的反应而分离出来。注射c-或v-ras对电压依赖性内向钙电流没有任何影响。IA的降低先于IC。注射c-ras而非v-ras导致的电流降低在40分钟后自发逆转。随着ras注射，IA稳态失活的电压依赖性向更负的电位移动。因此，ras介导的细胞转化可能涉及，也许作为初始事件，膜电流的长期改变。
