Effect Of Bortezomib On Functional Contraction Of Vascular Smooth Muscle In Mice

Objective: Our study aims to explore the mechanism of bortezomib contraction on thoracic aorta in mice by detecting the expression of thoracic aortic contractile proteins and their genes.Direct incubation of thoracic aorta in C57BL/6 male mice by using bortezomib and intraperitoneal injection of bortezomib to C57BL/6 mice,and then isolated the mouse thoracic aorta,detected the effect of bortezomib on functional contraction of mouse thoracic aorta.Methods: 1.Mouse vascular contractility was detected by myography vascular tension.The thoracic aortas of C57BL/6 male mice(6-8 weeks old)were cut into the ring segments with the same length(~2 mm)for organ culture with and without the presence of bortezomib(0,2,20,200 n M)for 24 h,followed by determining contractile responses to KCl and phenylephrine(PE).In the in vivo studies,C57BL/6 male mice(n=30,6-8 weeks old)were randomly divided in to two groups with intraperitoneal injection of saline or bortezomib(0.1 ?g/g)once every 3 days,respectively,for 4 weeks,detcting the effect of bortezomib on the indirect contraction of thoracic aorta,simultaneous measurement of heart rate and blood pressure by mouse arterial pressure,observe whether the contraction of bortezomib on mice has an effect on blood pressure and heart rate.2.According to method 1 in the bortezomib intraperitoneal injection of mouse groups and doses,after 4 weeks,the thoracic aorta was isolated and the expression of contractile proteins and genes such as SM ?-actin,calponin,and SM 22,and myocardin were detected by western blotting and fluorescent quantitative PCR,to investigate the mechanism of bortezomib on vasoconstriction.3.According to method 1 in the bortezomib intraperitoneal injection of mouse groups and doses,after 4 weeks,mice were weighed before and after intraperitoneal injection.Detection of thoracic aorta chymotrypsin activity by Fluorescent peptide substrate assay and morphological changes of thoracic aorta in C57BL/6 mice by HE staining,to investigate the effect and adverse reactions of bortezomib on mouse thoracic aorta.Results: 1.Incubation experiment shows,20 n M bortezomib(P<0.05)and 200 n M bortezomib(P<0.01)significantly inhibited thoracic aortic systolic function in C57BL/6 mice.After intraperitoneal injection of 0.1 ?g/g bortezomib for 4 weeks,bortezomib inhibited the systolic function of thoracic aorta in C57BL/6 mice regardless of whether the thoracic aorta was removed or not(P<0.05).There was no significant effect on heart rate,systolic blood pressure(SBP),diastolic blood pressure(DBP),and mean arterial pressure(MAP)in mice.2.The protein and gene expression of SM ?-actin,calponin and SM 22 in thoracic aortas of C57BL/6 mice was significantly down-regulated by intraperitoneal injection of bortezomib.3.The chymotrypsin activity of mouse thoracic aorta was inhibited(P<0.05)and there was no significant effect on the morphology of thoracic aorta in mice and the weight of mice.Conclusions: Bortezomib can reduce the expression of SM ?-actin,calponin and SM 22 and inhibit the systolic function of thoracic aorta in C57BL/6 mice.The mechanism may be down-regulation of myocardin gene expression,resulting in decreased myocardin protein expression,thereby down-regulating vasoconstrictor proteins and inhibiting vascular smooth muscle contraction.