Effects Of Low-intensity Pulsed Ultrasound On The Contraction Of Rats Bladder Smooth Muscle In Vitro And Its Mechanism Of Signaling Pathway

Part 1 Effects oflow-intensity pulsed ultrasound on thecontraction of rats bladder smooth musclein vitroObjective:To observe the influence oflow-intensity pulsed ultrasound(LIPUS) on the contraction of rats bladder smooth muscle in vitro.Methods:1、Totally 32 bladder smooth muscle strips of 32 female SD rats in vitro were prepared.2、They were randomly divided into four groups: ultrasound exposure group, ultrasound+nimodipine group, ultrasound+low molecular weight heparin group, control group.(each n=8)3、The contraction curves were measured and recorded with BL-410 F biological function experimental system before and after LIPUS irradiation.The contraction frequency and amplitude were analyzed.4、The bladder smooth muscle histopathology of ultrasound exposure group(after LIPUS irradiation) and control group were observed under the microscope.Results:1 、 The contraction frequency and amplitude of bladdersmooth muscle significantly increased in ultrasound exposure group after LIPUS irradiation(P<0.05).2 、 The contraction frequency and amplitude of bladder smooth musclesignificantly decreased in ultrasound+nimodipine group after LIPUS irradiation(P<0.05).3、The contraction frequency and amplitude of bladder smooth muscle wereno obvious difference in ultrasound+low molecular weight heparin group after LIPUS irradiation(P>0.05).4、Bladder smooth muscle cells had no obvious morphologic changes between ultrasound exposure group and control group.Conclusion:L-type calcium channels in bladder smooth muscle cells areactivated by LIPUS, which can increasethe contractility of bladder smooth muscle.Part two Mechanism research oflow-intensitypulsed ultrasound on the effectsof contraction of ratsbladder smooth musclePurpose: To investigate whether LIPUS could acceleratebladder smooth muscle(BSM) contraction by opening the L-type calcium channelsand activating the Ca2+ signaling pathway.Methods: The BSM cells were enzymatically isolated using papain and collagenase, identified by a-Actin specific antibody staining; The experiment was randomly divided into three groups: the 0.5 W/cm2 group,the 1.0 W/cm2 group and the 1.5 W/cm2 group. The exposure times for every experimental group were 10, 20, 30, 40, 50 sec, and control group with sham irradiation; The intracellular Ca2+ concentration was analyzed by flow cytometry with following four groups: control, ultrasound exposure,nimodipine, nimodipine followed by ultrasound.Results: The BSM cells were constructed and identified successfully;LIPUS with an intensity of 0.5 W/cm2 and an insonation time of 20 sec did not cause obvious cell death, with a percentage of survival cells of > 90%.Such a level of insonation was therefore used for following experiments;The concentration of Ca2+ was markedly enhanced by about 2.0-fold than that without LIPUS exposure(P<0.05). Besides, nimodipine could suppress theconcentration of intracellular Ca2+ which was caused by ultrasound(P<0.05).Conclusions: The results suggested LIPUS had potential therapeutic effect on PUR and the Ca2+ signaling pathway was involved in the mechanism. The ultrasoundirradiation may provide a new method for PUR therapy.