Investigation of Mechanisms of Volatile Anesthetic Action by the Use of Gene Expression Techniques

在这项研究的第一年，我们研究了挥发性麻醉药异氟烷和七氟烷对KvLQT 1和minK共表达的克隆I_的影响。<Ks>将体外转录自正常大鼠心脏cDNA的minK mRNA与KvLQT 1 mRNA一起注入卵母细胞后，可诱导电流。采用双电极电压钳记录技术，研究了异氟醚（0 - 1.5MAC）和七氟醚（0 - 1.5MAC）对水貂KvLQT 1电流和单独KvLQT 1电流的影响。<Ks>在2秒去极化至+40 mV后，异氟烷和七氟烷引起I_和KvLQT 1电流的电位依赖性降低。<Ks>两种挥发性麻醉药均能加速I_2和KvLQT 1电流的失活。<Ks>结论：吸入麻醉药对克隆I_2的显著抑制作用可能与临床观察到的麻醉药延长心室复极（Q-T间期）有关。<Ks >在接下来的一年中，我们从大鼠心脏中克隆了LCNQ1的另一个截短剪接变体。从TCNQT1的缺失序列来看，大鼠在这一部分的基因组结构可能与人类和小鼠的基因组结构不同。在过去的一年中，我们研究了由β_或β_亚基重构的Ca ^&lt;2 +&gt;通道的单通道特性，并与天然通道的特性进行了比较。<2a><2c>与β_亚基相反，β ^亚基和天然通道的Ca ^&lt;2 +&gt;通道以长持续关闭为主。<2a><2c>含β_亚基的Ca ^&lt;2 +&gt;通道的单通道特性与天然通道无明显区别。<2c>这些结果表明，β_亚基是大鼠心脏的功能性β亚基之一。<2c>

In the first year of this investigation, we investigated the effects of the volatile anesthetics isoflurane and sevoflurane on cloned I_<Ks> coexpressed by KvLQT1 and minK. Currents were induced following injection into oocytes of KvLQT1 mRNA with or without minK mRNA, which were transcribed in vitro from cDNAs of normal rats hearts. A Two-electrode voltage-clamp recording technique was used to investigate the effects of isoflurane (0-1.5 MAC) and sevoflurane (0-1.5 MAC) on I_<Ks> (KvLQT1 with mink) and KvLQT1 alone currents. Following a 2-s depolarization to +40 mV, isoflurane and sevoflurane caused potency-dependent reductions in I_<Ks> and KvLQT1 currents. Both of the volatile anesthetics tested accelerated the deactivation of I_<Ks> and KvLQT1 currents. We conclude that the significant inhibitory effect of volatile anesthetics on the cloned I_<Ks > may partly contribute to the clinical observations of the prolongation of the ventricular repolarization (Q-T interval) by the anesthetics. In the following year, we cloned another truncated splice variant of LCNQ1 from rat heart. Judging from the deleted sequence of the TCNQT1, the genomic structure of rat in this portion might be different from those of human and mouse. In the last year, we investigated the single-channel properties of the Ca^<2+> channels reconstituted with β_<2a> or β_<2c> subunit, and compared them with the properties of naive channel. In contrast to β_<2a> subunit, long-lasting closings were dominant in the Ca^<2+> channel with β^<2c> subunit and the native channel. The single-channel properties of Ca^<2+> channel with β_<2c> subunit were indistinguishable from those of native channel. Those findings suggest that β_<2c> subunit is one of the functional β subunits in the rat heart.