Effect Of Paritial Ureteral Obstruction On The Morphology, Autorhythmicity And Contractile Function Of Smooth Muscle In Rats

Objective:To analyze the effect of paritial unilateral ureteral obstruction(PUUO) on the morphology,autorhythrnicity and contractile function of smooth muscle in rats.Methods:Eighty Wistar rats were randomized into four groups:8-week experimental group (n=20) and sham control group(n=20),16-week experimental group(n=20) and sham control group(n=20).Experimental animals(n=40) had been embedded the upper half of left ureters into the psoas muscles.Sham control rats only received laparotomy.After the model are established the rats are separated in different experimental point to carry out the experiment of the ureteral muscle strip in vitro,the contraction extent and frequency of the muscle strip were determined and the ultrastructural changes were observed through transmission electron microscope.Results:1,The ureter contractility and contractile frequency in 8-week experimental group were (0.62±0.38 g) and(9.26±3.35/30sec),and in the sham control group were(0.25±0.39 g) and(7.40±2.49/30see).There was a significant increase in the 8-week experimental group compared with sham control group(P＜0.05).2,The ureter contractility and contractile frequency of 16-week experimental group were(0.15±0.10 g) and(6.42±1.66/30sec),while sham control group were(0.41±0.38g) and (8.24±1.72/30see).There was a significant decrease in the 16-week experimental group compared with sham control group(P＜0.05).3,We can observe the ultrastructure of the ureter by transmission electron microscope.In 8-week experimental group there were massive mitochondria in the endochylema of smooth muscle cell,whereas in 16-week experimental group,the number of mitochondria decrease and mitochondria is swelling and vacuolization.There are many collagen fibers in the experimental rats' in intercellular substance.Conclusions:1,Compared with the control group rats,the autorhythmicity and contraction force of the ureter smooth muscle increased,which maybe due to compensation in the initial stage.While the autorhythmicity and contraction force of the ureter smooth muscle were decreased,the reason of it should be decompensated in advanced stage.2,By the transmission electron microscope,we can observe that there are massive mitochondria in the endochylema of smooth muscle cell in early stage,while the number of mitochondria decrease and the morphous of mitochondria is swelling and vacuolization. We also finded that there are many collagen fibers in intercellular substance in advanced stage.