| Objective: To investigate the biological effects of prostaglandin E2(PGE2)and its receptor binding in ureteral smooth muscle on stone removal during ureteral contraction/diastole,and to provide a new theoretical basis for PGE2 as a pro-lithotriptic biomolecule and a new idea for ureteral stone treatment.Methods: To determine the expression and location of E2 receptors in ureteral myofibroblasts by immunofluorescence and WB techniques.Further tension experiments were performed using an ex vivo ureteral model under PGE2 and EP receptor blockade and agonism conditions to verify their biological functions.We further verified the EP receptor expression and PGE2 content level by constructing an animal experimental model in rabbits and collecting ureteral tissues at different times after surgery to further confirm its biological function of ureteral contraction/diastole in a complete obstruction model.Results: 1.Western blot results suggested that ureteral smooth muscle cells expressed Prostaglandin E2 receptor 2(EP2)and Prostaglandin E2 receptor 4(EP4),and immunofluorescence suggested that EP2 was localized in the cell membrane;EP4 was localized in the nucleus.2.By rabbit isolated ureteral tone assay,we found that PGE2 could show concentrationdependent diastolic hyperkalemia-induced ureteral tissue contraction EC50 of 2.253×10-7 M.After adding EP2 receptor antagonist,the diastolic effect disappeared,suggesting that the diastole was triggered by the binding of PGE2 to EP2.3.In the animal experimental part,imaging suggested the presence of high-density shadow in the lower abdomen of rabbits,and dissection could observe the presence of ureteral stones in the ureteral lumen and an incomplete obstruction model.4.WB of isolated tissues suggested that there was no significant difference in protein expression of EP2 in normal rabbit ureters at various sites of ureter(P > 0.05).EP2 protein expression in the left upper ureter at different days was statistically significant by ANOVA(F=52.51,P<0.000),and the expression was highest on postoperative day 3,with a decreasing trend with increasing time.Membrane-bound prostaglandin E2 synthase-1(m PGES-1)protein expression in the left upper ureter at different days was statistically significant by ANOVA(F=228.9,P<0.000),with the highest expression on postoperative day 1,followed by a gradual decrease.Conclusion: 1.In ureteral tissue,PGE2 produces a diastolic ureteral effect by binding to EP2 receptors on smooth muscle.2.In the ureteral stone model,PGE2 binds to ureteral smooth muscle EP2 receptors,and the increased PGE2 synthesis and increased EP2 receptor protein expression in the obstructed state achieve the biological function of ureteral diastole,which becomes a favorable factor for stone elimination. |
