Evaluation of ureteric contraction: a comparison among ring, spiral-cut and longitudinal segments

Objective To determine the optimal contractile response of isolated meters to inflammatory mediators and neurotransmitters by evaluating four common m ethods of ureteric suspension. Materials and methods Ureters from adult domestic swine were placed immedia tely in Krebs buffer and cut into 4-5 mm segments. Four methods of suspensi on were compared: (i) an unopened ring segment suspended horizontally; (ii) a spirally cut segment (lumen cut open at a 45 degrees and suspended end-t o-end); (iii) an open longitudinal segment; and (iv) a closed longitudinal segment, All segments were placed in individual water-jacketed tissue baths containing Krebs buffer, the frequency of contraction measured using a for ce transducer and registered on a polygraph. The sensitivity of all four se gments was tested by measuring the tension and frequency in response to inc reasing frequencies of electric field stimulation, and by a cumulative conc entration-response curve to carbachol. Results Ureteric segments responded with an increased frequency of contract ion depending on the intensity of stimulus to both electric field stimulati on and carbachol. However, there were no significant differences in spontan eous levels of contraction, sensitivity or maximal response among the metho ds of suspension in response to electric field stimulation or carbachol, Conclusion These results indicate that all four methods of suspending the u reteric segments produce contractile responses sensitive enough to study th e action of various neurotransmitters.