An Experimental Study: The Effect Of Low Intensity Ultrasound On The Contraction Of Uterine Smooth Muscle In Rats In Vivo

Objective:To study the influence of low intensity ultrasound on the contraction of uterine smooth muscle in rats in vivo and to find the mechanism of the contraction of uterine smooth muscle by ultrasound; To find the experimental evidence of low intensity ultrasound in postpartum hemorrhage prevention and treatment.Methods: 1. The uteri in rats in vivo were irradiated by low intensity ultrasound (0.8MHz,2W/cm2) for 10 min. The contraction frequency, amplitude, tension and activity were noted with BL-410 biological experimental system and the changes of the temperature were measured, after that the histopathologic alterations were observed by light microscope and transmission electron microscope to explore the optimal suitable parameters. 2. The forty Wistar rats were randomly divided into 4 groups: group A (normal control group), group B (ultrasound group), group C (oxytocin group) and group D (ultrasound + oxytocin group), their contraction information was recorded to explore the disparity among them. 3. The method of immunohistochemistry was used to test the expression of conjunction protein 43 in smooth-musle of uterus, and light microscope was used to observe the results computer image analysis technology was also considered to get a conclusion.Results:1. It could be seen that the contraction frequency, amplitude, tension and contraction activity were significantly increased under 2W/cm2 ultrasonic irradiation for 10 minutes(p<0.05).2. The histological structure and ultramicrostructure of the uterine smooth muscle did not have an abnormal change under the ultrasound of intensity of 2W/cm2 for 10 minutes and the temperature increased for 3℃.3.The contraction frequency, amplitude, tension and contraction activity of group B, group C and group D were superior to group A(P<0.05); The contraction frequency, tension and contraction activity of group C were superior to B group(P<0.05); The contraction frequency, amplitude,tension and contraction activity of group D were superior to group B(P<0.05); The contraction amplitude and contraction activity of group D were superior to group C(P<0.05).4. The expression of Cx43 was found either in kytoplasm or on membrane of smooth-muscle cell of uterus in light microscope, and shown as brown particles. Positive expression was much greater in ultrasound group than in control group both in color and extension. The average gradation of Cx43 was 34.24±6.93 and 70.56±6.81 in control group and ultrasound group respectively. The variability had statistical significance (p<0.05).Conclusion:1. Low intensity ultrasound can induce uterine smooth muscle contraction in rats.2. Low intensity ultrasound can intensify the function of oxytocin and the contraction frequency, tension and contraction activity were significantly increased under its irradiation.3. The ultrasound can increase the expression of Cx43 protein in smooth-muscle of uterus.