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

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Abstract
To determine the optimal contractile response of isolated ureters to inflammatory mediators and neurotransmitters by evaluating four common methods of ureteric suspension. Ureters from adult domestic swine were placed immediately in Krebs buffer and cut into 4-5 mm segments. Four methods of suspension were compared: (i) an unopened ring segment suspended horizontally; (ii) a spirally cut segment (lumen cut open at a 45 degrees and suspended end-to-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 force transducer and registered on a polygraph. The sensitivity of all four segments was tested by measuring the tension and frequency in response to increasing frequencies of electric field stimulation, and by a cumulative concentration-response curve to carbachol. Ureteric segments responded with an increased frequency of contraction depending on the intensity of stimulus to both electric field stimulation and carbachol. However, there were no significant differences in spontaneous levels of contraction, sensitivity or maximal response among the methods of suspension in response to electric field stimulation or carbachol. These results indicate that all four methods of suspending the ureteric segments produce contractile responses sensitive enough to study the action of various neurotransmitters.