川芎嗪对模拟失重大鼠颈动脉平滑肌Ca2+敏感性的影响

目的：探讨川芎嗪对模拟失重大鼠颈动脉平滑肌收缩蛋白Ca²⁺敏感性的影响及机制。方法：21只雌性SD大鼠分为对照组（CON）、模拟失重组（TS）、模拟失重+川芎嗪灌饲组（LTZ）（n=7）。4周后测定大鼠颈动脉收缩性、收缩蛋白Ca²⁺敏感性及肌球蛋白轻链激酶抑制剂ML-7对以上指标的影响。结果：TS组苯肾上腺素（PHE）收缩力比CON组高25.14%（P<0.01），LTZ组较TS组低13.46%（P<0.01），较CON组高8.30%；ML-7可使CON、TS、LTZ组PHE收缩力分别降低8.84%、16.24%（P<0.01）和3.40%；TS组KCl收缩力比CON组高40.46%（P<0.01），LTZ组较TS组低18.80%，较CON组高14.05%；ML-7可使CON、TS、LTZ组KCl收缩力分别降低21.97%（P<0.05）、21.88%（P<0.01）和10.84%；TS组pD2Ca²⁺]比CON组高10.03%（P<0.01），LTZ组较TS组低7.01%（P<0.01），较CON组高2.32%；ML-7可使CON、TS、LTZ组pD2Ca²⁺]分别降低2.42%、7.43%（P<0.01）和2.51%。结论：模拟失重大鼠颈动脉收缩增强可能是由动脉平滑肌收缩蛋白Ca²⁺敏感性增强所导致的。川芎嗪可改善模拟失重大鼠颈动脉的收缩功能，其机制可能与抑制血管平滑肌肌球蛋白轻链激酶继而降低Ca²⁺敏感性有关。

Effects of ligustrazine on the Ca2+ sensitivity in carotid artery smooth muscle of simulated weightlessness rats

Objective:To study the effects of Ligustrazine on the Ca²⁺ sensitivity in carotid artery smooth muscle of simulated weightless-ness rats. Methods:Twenty-one female SD rats were divided into control group (CON), simulated weightlessness group (TS), simulated weightlessness plus Ligustrazine administration group (LTZ) (n=7). After 4 weeks, the contractile property and the Ca²⁺ sensitivity in carotid artery were measured. Furthermore, the effects of ML-7(a myosin light chain kinase specific inhibitor) on above mentioned parameters were recorded. Results:Compared with CON group, the contractile force induced by phenylephrine (PHE) in TS group was increased by 25.14% (P<0.01). The force in LTZ group decreased by 13.46% (P<0.01) and increased by 8.30% compared with TS and CON group, respec-tively. After the artery rings were incubated with ML-7, the force in CON, TS and LTZ group were reduced by 8.84%, 16.24% (P<0.01) and 3.40%, respectively. Compared with CON group, the contractile force induced by KCl in TS group was increased by 40.46% (P<0.01). The force in LTZ group decreased by 18.80% and increased by 14.05% compared with TS and CON group, respectively. The force in CON, TS and LTZ group were reduced by 21.97% (P<0.05), 21.88% (P<0.01) and 10.84% by ML-7, respectively. Compared with CON group, the pD2Ca²⁺] in TS group was increased by 10.03% (P<0.01). The pD2Ca²⁺] in LTZ group was decreased by 7.01% (P<0.01) and increased by 2.32% compared with TS and CON group, respectively. The pD2Ca²⁺] in CON, TS and LTZ group was reduced by 2.42%, 7.43% (P<0.01) and 2.51% by ML-7, respectively. Conclusion:The contraction of carotid artery is strength-ened in simulated weightlessness rats, it maybe results from the Ca²⁺ sensitivity of contractile proteins in smooth muscle increasing. Ligus-trazine can improve the contraction of carotid artery, reducing the Ca²⁺ sensitivity and inhibiting myosin light chain kinase may be involved in its mechanisms.