Aim: The aim of this study was to evaluate whether tamsulosin, an alpha-blocker, has an effect on decreasing spontaneous ureteral contractility with or without phenylephrine, an alpha-agonist. Additionally, nifedipine and a terpene mixture (Rowatinex®) were tested and compared with each other.
Methods: We obtained ureteral segments from freshly killed eight-week-old rabbits. Preparation was performed in an aerated Krebs buffer (95% oxygen and 5% carbon dioxide) at a constant temperature of 37 °C. All segments were suspended into organ tissue baths containing aerated Krebs buffer using stainless steel hangers and clips. The ureter was divided into four segments: upper, middle, low and uretero-vesical junction. Each ureteral segment was suspended longitudinally and circularly by opposite corners, respectively. Tamsulosin, nifedipine, and the terpene mixture were separately applied into the segments. Contractile activities of each drug were recorded and analyzed by the PowerLab data acquisition system (AD instruments CO., USA). The area under the curve was compared between before and after each drug application for each 5 minutes with or without pheylephrine. Statistical analysis was performed using the unpaired Student's t test.
Results: Under Krebs solution, ureteral smooth muscle contractility was significantly decreased in all segments over 10(-6) M in tamsulosin, 10(-7) M in nifedipine and 0.001x1 concentrations in the terpene mixture (P=0.038). However, under Krebs solution with 10(-5) M phenylephrine, there was no significant difference at all concentrations in tamsoluin and nifedipine. In contrast to tamsolusin and nifedipine, there was a significant decrease in ureteral smooth muscle contractility in most of segments at 0.01x1 concentrations (P=0.042) in the terpene mixture.
Conclusion: Tamsulosin, nifedipine, and the terpene mixture showed the effect on spontaneous ureteral contractility. In particular, the terpene mixture might have the better effect on decreasing ureteral smooth muscle contractility.