杜鹃素通过激活Kv7通道舒张小鼠离体肺动脉

Farrerol relaxes isolated mouse pulmonary arteries by activating Kv7 channels

摘要:

目的]探究杜鹃素对不同收缩剂预刺激后小鼠离体肺动脉血管环的舒张作用,以及该作用是否与Kv7通道有关。 [方法]利用血管张力测定系统,测定肺动脉血管环的肌张力。首先检测10－8 mol/L去甲肾上腺素(NE)或10－7 mol/L 5-羟色胺(5-HT)预收缩肺动脉后,10－6、3×10－6、10－5、3×10－5、10－4 mol/L杜鹃素的舒张作用。观察肺动脉内皮是否完整对杜鹃素舒张肺动脉血管环的影响。检测预先孵育杜鹃素(RC₅₀,60 min)对NE(10－10～10－7 mol/L)和5-HT(10－8～10－5 mol/L)梯度收缩肺动脉的抑制作用。Fluo 4-AM荧光钙离子探针实验检测杜鹃素对急性分离获得的小鼠肺动脉平滑肌细胞(PASMC)中[Ca²＋]_in的影响。观察Kv7通道阻滞剂XE991 1 μmol/L孵育15 min对杜鹃素梯度舒张肺动脉的影响。 [结果]杜鹃素(10－6～10－4 mol/L)能够显著舒张经NE或5-HT预收缩的肺动脉血管环(P＜0.01),其舒张作用呈非内皮依赖性；预先孵育杜鹃素(RC₅₀,60 min)可显著减弱NE及5-HT所引发的肺动脉最大收缩反应(P＜0.01)；Fluo 4-AM实验表明,KCl能够显著升高PASMC中的[Ca²＋]_in,而RC₅₀杜鹃素对这一现象具有显著的抑制作用(P＜0.01)；孵育Kv7通道阻滞剂(1 μmol/L XE991,15 min)后,杜鹃素对NE及5-HT预收缩小鼠肺动脉的舒张作用得到显著抑制(P＜0.01)。 [结论]杜鹃素通过激活Kv7通道舒张小鼠离体肺动脉。

Abstract:

Aim To investigate the relaxation effect of farrerol on isolated mouse pulmonary artery (PA) rings pre-contracted with different vasoconstrictors, and to determine whether this effect is related to the Kv7 channels. Methods The vascular tension was measured in pulmonary artery rings using wire myography. Firstly, the vasodilatory effects of farrerol at concentrations of 10－6,3×10－6,0－5,3×10－5 and 10－4 mol/L were examined after pre-contraction of pulmonary arteries with 10－8 mol/L norepinephrine (NE) or 10－7 mol/L 5-hydroxytryptamine (5-HT). The influence of the presence or absence of PA endothelium on farrerol-induced relaxation of PA rings was observed. The inhibitory effect of pre-incubation with farrerol (RC₅₀, 60 min) on the graded contraction of PA induced by NE (10－10～10－7 mol/L) and 5-HT (10－8～10－5 mol/L) was measured. The effect of farrerol on intracellular calcium concentration ([Ca²＋]_in) in acute isolated mouse pulmonary arterial smooth muscle cell (PASMC) was detected using the Fluo 4-AM fluorescent calcium probe. Finally, the effect of the Kv7 channels blocker XE991 (1 μmol/L, 15 min incubation) on farrerol-induced graded relaxation of pulmonary arteries was observed. Results Farrerol (10－6～10－4 mol/L) significantly relaxed PA rings pre-contracted with NE or 5-HT (P＜0.01), and this relaxing effect was endothelium-independent. Pre-incubation with farrerol at concentration of RC₅₀ for 60 min markedly attenuated the maximal contractions induced by both NE (10－10～10－7 mol/L) and 5-HT (10－8～10－5 mol/L). Furthermore, in PASMC loaded with Fluo 4-AM, farrerol (RC₅₀) significantly inhibited the 30 mmol/L KCl-induced elevation of [Ca²＋]_in (P＜0.01). Pre-treatment with the blocker XE991 (1 μmol/L 15 min) significantly attenuated farrerol-induced relaxation (P＜0.01). Conclusion Farrerol relaxes isolated mouse PA by activating Kv7 channels.