ISOLATED HUMAN COLON STRIPS AS A PHARMACOLOGICAL TOOL

The spontaneous activity of isolated human colon strips was studied to obtain homogeneous results with a reproducible model. The strips of m acroscopically normal appearance were mounted in an organ bath contain ing Krebs solution at 32 degrees C or Tyrode solution at 37 degrees C. Mechanical activity was recorded by an isometric transducer. Spontane ous motility did not occur in all preparations. Moreover, when observe d, it could not always be evaluated. The percentage of strips with spo ntaneous activity was lower with Tyrode solution than with Krebs solut ion (65 vs. 81%). KCl did not induce a plateau contraction. Acetylchol ine induced concentration-dependent contractions, with a significantly different pD(2) : 4.43 +/- 0.39 and 5.59 +/- 0.16 for Krebs and Tyrod e, respectively. Isoprenaline abolished spontaneous motility in Krebs solution. Only 20% of specimens presented evaluable motility. Krebs so lution may be the best conditions for studying the effects of drugs on spontaneous motility, while Tyrode solution can be used to investigat e the effects of contractile agents.