Chen Yu, Xu Zhao-Xia, Zhang Hui-Rong, Wu Ying, Shi Li-Jun
Key Laboratory of Physical Fitness and Exercise, Ministry of Education, Beijing Sport University, Beijing 100084, China.
Zhongguo Ying Yong Sheng Li Xue Za Zhi. 2018 May 8;34(5):470-475. doi: 10.12047/j.cjap.5675.2018.107.
To investigate the mechanisms through which myocyte large-conductance Ca-activated K (BK) channels mediate the vasodilation effects of melatonin on cerebral arteries (CAs).
Middle cerebral arteries (MCA) were obtained from 8-week-old male Wistar rats after anaesthetized. Middle cerebral arterial smooth muscle cells were enzymatically isolated. Whole cell recording mode of patch clamp technique was used to measure the current density of BK channel and voltage-gated potassium (K) channel before and after adding melatonin. Currents density of melatonin on BK channels with melatonin receptor inhibitor 2-phenyl-N-acetyl (luzindole) was recorded using whole cell recording mode and open probability (Po) was recorded using single-channel attached recording mode. The conductance (G) and average open time (To) and off time (Tc) of the BK channel were detected before and after the addition of melatonin in the internal-outward mode.
① Melatonin markedly increased the whole-cell BK channel current density but not the voltage-gated potassium (K) channel current density. ② Luzindole (1 μmol/L) greatly suppressed melatonin-induced increase of BK channel current density. ③ The Po of BK channel was significantly increased by melatonin (100 μmol/L) under cell attached recording mode, which was markedly inhibited by luzindole (1 μmol/L). ④ In inside-outside recording mode, melatonin (1 μmol/L, 100 μmol/L) reduced both To and Tc of BK channel, and Tc was reduced much more than To.
Melatonin mediates vasodilation of MCA through the activation of BK channels both melatonin receptor dependent and independent mode.
探讨心肌细胞大电导钙激活钾（BK）通道介导褪黑素对脑动脉（CAs）舒张作用的机制。
取8周龄雄性Wistar大鼠，麻醉后获取大脑中动脉（MCA）。酶法分离大脑中动脉平滑肌细胞。采用膜片钳技术的全细胞记录模式，测量添加褪黑素前后BK通道和电压门控钾（K）通道的电流密度。使用全细胞记录模式记录褪黑素受体抑制剂2-苯基-N-乙酰（鲁辛朵）存在时褪黑素对BK通道的电流密度，采用单通道贴附记录模式记录开放概率（Po）。以内向外模式检测添加褪黑素前后BK通道的电导（G）、平均开放时间（To）和关闭时间（Tc）。
①褪黑素显著增加全细胞BK通道电流密度，但不增加电压门控钾（K）通道电流密度。②鲁辛朵（1 μmol/L）显著抑制褪黑素诱导的BK通道电流密度增加。③在细胞贴附记录模式下，褪黑素（100 μmol/L）显著增加BK通道的Po，这被鲁辛朵（1 μmol/L）显著抑制。④在内外模式记录中，褪黑素（1 μmol/L，100 μmol/L）降低了BK通道的To和Tc，且Tc降低幅度大于To。
褪黑素通过依赖和不依赖褪黑素受体的方式激活BK通道介导MCA的舒张。
