National Research Laboratory for Mitochondrial Signaling, Department of Physiology, College of Medicine, Cardiovascular and Metabolic Disease Center, FIRST Mitochondrial Research Group, Biomarker Medical Research Center, Inje University, Korea.
J Pharmacol Sci. 2010;112(1):64-72. doi: 10.1254/jphs.09228fp.
We investigated the effects of YC-1, an activator of soluble guanylyl cyclase (sGC), on voltage-dependent K+ (Kv) channels in smooth muscle cells from freshly isolated rabbit coronary arteries by using the whole-cell patch clamp technique. YC-1 inhibited the Kv current in a dose-dependent fashion with an apparent K(d) of 9.67 microM. It accelerated the decay rate of Kv channel inactivation without altering the kinetics of current activation. The rate constants of association and dissociation for YC-1 were 0.36 +/- 0.01 microM(-1) x s(-1) and 3.44 +/- 0.22 s(-1), respectively. YC-1 did not have a significant effect on the steady-state activation and inactivation curves. The recovery time constant from inactivation was decreased in the presence of YC-1, and application of train pulses (1 or 2 Hz) caused a progressive increase in the YC-1 blockade, indicating that YC-1-induced inhibition of Kv currents is use-dependent. Pretreatment with Bay 41-2272 (also a sGC activator), ODQ (a sGC inhibitor), or Rp-8-Br-PET-cGMPs (a protein kinase G inhibitor) did not affect the basal Kv current and also did not significantly alter the inhibitory effect of YC-1. From these results, we suggest that YC-1 directly inhibits the Kv current independently of sGC activation and in a state-, time-, and use-dependent fashion.
我们使用全细胞膜片钳技术研究了可溶性鸟苷酸环化酶（sGC）激活剂 YC-1 对新鲜分离的兔冠状动脉平滑肌细胞电压依赖性钾通道（Kv 通道）的影响。YC-1 以剂量依赖的方式抑制 Kv 电流，表观 K(d)为 9.67 μM。它加速 Kv 通道失活的衰减速率，而不改变电流激活的动力学。YC-1 的缔合和解离速率常数分别为 0.36 ± 0.01 μM(-1) x s(-1)和 3.44 ± 0.22 s(-1)。YC-1 对稳态激活和失活曲线没有显著影响。在 YC-1 存在的情况下，失活后的恢复时间常数缩短，应用连续脉冲（1 或 2 Hz）会导致 YC-1 阻断逐渐增加，表明 YC-1 诱导的 Kv 电流抑制是使用依赖性的。用 Bay 41-2272（也是 sGC 激活剂）、ODQ（sGC 抑制剂）或 Rp-8-Br-PET-cGMPs（蛋白激酶 G 抑制剂）预处理不会影响基础 Kv 电流，也不会显著改变 YC-1 的抑制作用。根据这些结果，我们认为 YC-1 直接抑制 Kv 电流，独立于 sGC 激活，呈状态、时间和使用依赖性。
