In vitro effects of nonsteroidal anti-inflammatory agents and prostaglandins I-2, E-2, and F-2 alpha on contractility of taenia of the large colon ofhorses

Objectives-To determine the in vitro effect of various prostaglandins (PG) and nonsteroidal anti-inflammatory drugs (NSAID) on contractile activity of the large-colon taenia of horses. Animals-14 healthy horses. Procedure-The taenia was collected from the ventral colon, cut into strips (2 x 10 mm), and mounted in a tissue bath system (20-ml capacity) that cont ained oxygenated Krebs buffer solution warmed to 37.5 +/- 0.5 C. After equi libration, incremental doses of PGE(2), PGF(2 alpha), PGl(2), flunixin megl umine, carprofen, ketoprofen, and phenylbutazone were added to the baths, a nd contractile activity was recorded. Magnitude of the response was calcula ted by comparing contractile activity before and after administration of th e PG or NSAID to the tissue baths. Results-PGE(2) and PGF(2 alpha) caused a significant increase in contractil e activity, whereas PGl(2) induced an inhibitory response. Activity of NSAI D on contraction was predominantly inhibitory. At low concentrations, ketop rofen induced an excitatory effect, which then became inhibitory at high co ncentrations. Compared with the other NSAID, carprofen significantly reduce d contractile activity at lower concentrations. Conclusions-PGE(2) and PGF(2 alpha) appear to enhance contractility of larg e-colon taenia of horses, whereas PGl(2) was inhibitory in the in vitro mod el. Administration of NSAID also inhibited contractility, with carprofen ha ving the most potent effect. Clinical Relevance-Administration of NSAID in combination with liberation o f endogenous PG may predispose horses to development of intestinal stasis a nd subsequent impaction.