Characterization of two types of calcium channels in mouse neuroblastoma cells.
Characterization of two types of calcium channels in mouse neuroblastoma cells.
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小鼠神经母细胞瘤细胞中两种钙通道的表征。
DOI：
10.1113/jphysiol.1987.sp016406
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发表时间：
1987
期刊：
影响因子：
--
通讯作者：
Yoshii,M
中科院分区：
文献类型：
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作者：
Narahashi,T;Tsunoo,A;Yoshii,M
1.在神经母细胞瘤细胞系N1E-115中鉴定和研究了两种电压敏感性钙通道。采用膜片电极电压钳全细胞变化法记录钙通道电流(50 MM)。2.通过阶跃去极化，从-80 mV的保持电位到-50 mV以上的正电位，诱发出一种瞬时的(I型)Ba2+内向电流。电流幅度在-20 mV左右达到最大。3.当去极化电位大于-20 mV时，可诱发内向Ba2+电流的持续时间较长的(II型)成分。该分量在+10 mV左右达到最大值，并且在持续400 ms的长时间去极化脉冲期间没有失活。4.当施加S条件脉冲5 mV至-30 mV时，阶跃去极化因失活而未能诱发出瞬时电流。然而，它引发了一股持久的电流。5.作为条件性去极化敏感成分的瞬时电流，随着膜去极化的增加，其时程变快，幅度变小。电流方向在+60 mV时仍为内向。6.从上述的电压敏感性和独立的通道活动来看，负责瞬时电流的钙通道(I型通道)和负责持久电流的钙通道(II型通道)被认为是两个不同的实体。7.Cd~(2+)优先阻断II型钙通道，而La~(3+)对这两种钙通道均有很强的阻断作用。8.多价阳离子阻断通道的相对效价(表观解离常数)为：La3+，远大于Ni2+1.5，比Cd~(2+)大47,160=Co2+，160；La3+，大于Cd~(2+)0.9，远大于Ni2+7.0，比Co2+大280,560。9.两种钙通道对温度的敏感性相同。温度系数(Q10)在20到30摄氏度之间估计为3.0，在20摄氏度以下为15.0。10.外用二丁酰腺苷3‘，5’-磷酸(二丁酰环AMP)(1 MM)可使II型电流的幅度增加30%-50%，但不能增强I型电流的成分。
1. Two types of voltage‐sensitive calcium channels were identified and studied in the neuroblastoma cell line N1E‐115. Calcium channel currents as carried by Ba2+ (50 mM) were recorded using the whole‐cell variation of the patch‐electrode voltage‐clamp technique. 2. A transient (type I) inward Ba2+ current was evoked by a step depolarization from a holding potential of ‐80 mV to potentials more positive than ‐50 mV. The current amplitude became maximum around ‐20 mV. 3. A depolarization to potentials more positive than ‐20 mV evoked a long‐lasting (type II) component of the inward Ba2+ current. This component reached its maximum around +10 mV and did not inactivate during a prolonged depolarizing pulse lasting 400 ms. 4. When preceded by a 5 s conditioning pulse to ‐30 mV, step depolarization failed to evoke a transient current due to inactivation. However, it induced a long‐lasting current. 5. A transient current isolated as the component sensitive to conditioning depolarization became faster in its time course and smaller in its amplitude with membrane depolarization. The current direction was still inward at +60 mV. 6. From the differential voltage sensitivity and the independent channel activity described above, calcium channels responsible for the transient current (type I channel) and those responsible for the long‐lasting current (type II channel) were considered to be two different entities. 7. Cd2+ preferentially blocked type II channels, whereas La3+ was a highly potent blocker for both types of calcium channels. 8. The relative potency for block by polyvalent cations was as follows (apparent dissociation constant in microM): La3+, 1.5 much greater than Ni2+, 47 greater than Cd2+, 160 = Co2+, 160 for type I channels, and La3+, 0.9 greater than Cd2+, 7.0 much greater than Ni2+, 280 greater than Co2+, 560 for type II channels. 9. The two types of calcium channels were equally sensitive to the temperature. The current amplitude was reduced by cooling below 30 degrees C. The temperature coefficient (Q10) value was estimated to be 3.0 between 20 and 30 degrees C, and 15.0 below 20 degrees C. Above 30 degrees C, warming reduced the amplitude slightly. 10. External application of dibutyryl adenosine 3',5'‐phosphate (dibutyryl cyclic AMP) (1 mM) caused an increase in the amplitude of the type II current by 30‐50%, while failing to enhance the type I component.(ABSTRACT TRUNCATED AT 400 WORDS)