Monovalent cation conductance of the sustained inward current in rabbit sinoatrial node cells
Monovalent cation conductance of the sustained inward current in rabbit sinoatrial node cells
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DOI：
10.1007/s004240050269
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发表时间：
1996-11-01
影响因子：
4.5
通讯作者：
Noma, A
中科院分区：
文献类型：
--
作者：
Guo, JQ;Ono, K;Noma, A
在全细胞钳夹下，用无Na+溶液灌流兔窦房结细胞，可抑制持续性内向电流（I-st），在保持电位-80 mV时，去极化负性小于-40 mV时可记录到L型钙电流（I-Ca，I-L）。另一方面，Mg ~（2+）替代Ca ~（2+）抑制内向的I-Ca、I-L和孤立的I-st。在此条件下，以尼卡地平敏感电流测量的I-st显示激活阈值在-60 ~-70 mV之间。通过用这些碱金属离子取代外部Na+，确定了一价离子的电导率顺序为Na+ > Li+> K+，K+与Cs+一致。讨论了I-st对舒张期除极的贡献。
Under the whole cell clamp, superfusion of the rabbit sinoatrial node cells with a Na+-free solution suppressed the sustained inward current (I-st), and the L-type Ca2+ current (I-Ca,I-L) could be recorded on depolarization less negative than -40 mV from the holding potential of -80 mV. On the other hand, replacement of Ca2+ with Mg2+ in the external solution suppressed inward-going I-Ca,I-L and isolated I-st. Under this condition, I-st measured as a nicardipine-sensitive current showed an activation threshold between -60 and -70 mV. The conductance sequence of I-st for monovalent ions was determined as Na+ > Li+ much greater than K+ congruent to Cs+ by replacing the external Na+ with these alkali metal ions. The contribution of I-st to the diastolic depolarization is discussed.