研究剪应力生物效应时难以回避压力的联合效应

The Unavoidable Combined Effect of Shear Stress and Normal Pressure in Investigation of Biological Effects induced by Shear Stress

目的:生物力药理学研究常用流动小室或血管段观察剪应力的生物学效应;法向压力可能参与其中。本文探讨不同剪应力和压力对家兔离体血管内皮细胞环氧化酶-1(COX-1)mRNA和组织纤溶酶源激活物(t-PA)mRNA表达水平的影响。方法:手术分离实验家兔腹主动脉共15段,应用离体血管灌流装置,建立家兔动脉血管在不同剪应力(1.5-20dyn/cm^2)和平均压力(<50 000dyn/cm^2)条件下的加载模型;实时荧光定量PCR(Real-time PCR)测定不同剪应力及压力水平时实验兔动脉血管COX-1mRNA、t-PA mRNA的表达水平及其相互关系。结果:(1)单独观察剪应力效应:剪应力在1.5-20dyn/cm^2范围内,COX-1mRNA和t-PA mRNA相对表达水平随着剪应力增加而升高,均呈显著正相关(P<0.01),回归方程分别为y=0.0261x+0.0886和y=0.2033x+1.2082。(2)综合观察剪应力和压力的联合效应:剪应力(x)和压力(y)以复杂的非线性方式显著影响COX-1mRNA和t-PA mRNA的表达,可采用二元二次方程进行定量描述,分别为COX-1mRNA=0.3619-0.0389x+8.8645×10^(-7)y+0.0015x^2+1.515×10^(-6)xy-3.1759×10^(-10)y^2(P<0.01)和t-PA mRNA=2.9572-0.047x-6.5219×10-5y+0.01x2+2.2973×10^(-6)xy+6.9716×10^(-10)y^2(P<0.01)。结论:生物力药理学研究剪应力的生物效应时,压力的影响不可避免,应综合分析剪应力与压力的联合作用,推荐采用二元二次方程进行有效描述。

Objective：In biomechanopharmacological research,flow chamber or blood vessel segment are frequently applied to study the biological effects of shear stress（SS）.Flowing was driven by pressure difference,so the normal pressure is possibly involved in inducing the biological effects.So in attempt to investigate whether pressure could affect the biological effects,the effects of different levels of shear stress and pressure on cyclooxygenase-1（COX-1）mRNA and tissue type plasminogen activator enzyme（t-PA）mRNA in rabbit artery vessels was ex vivo observed.Method：By employing ex vivo arterial perfusion system,the rabbit artery perfusion model was established under different flow conditions of SS（1.5-20dyn/cm^2）and mean normal pressure（ 〈50 000dyn/cm^2）.And the expression of COX-1mRNA and t-PA mRNA was measured by real-time PCR method.Results：When considering the effect of SS on COX-1mRNA and t-PA mRNA expression separately,under flow oondition of SS（1.5-20dyn/cm^2）the detection results of real-time PCR of COX-1 mRNA and t-PA mRNA expression（y）showed increased and a significant positive correlation with SS（x）,respectively,the linear equation was described：y=0.0261x＋0.0886（P〈0.01）and y=0.2033x＋1.2082（P〈0.01）accordingly.And we also found that SS（x）and pressure（y）had a significant combined effect on expression of COX-1mRNA and t-PA mRNA,the binary quadratic equations were established：COX-1 mRNA = 0.3619-0.0389x＋8.8645×10^（-7）y＋0.0015x^2＋1.515×10^（-6）xy-3.1759×10^（-10）y^2（P〈0.01）;t-PA mRNA = 2.9572-0.047x-6.5219×10-5y＋0.01x^2＋2.2973×10^（-6）xy＋6.9716×10^（-10）y^2（P〈0.01）.Conclusion：The combined effects of SS and normal pressure should be considered in biomechanopharmacological research.Our result demonstrates that binary quadratic equation is an effective description quantitatively.