EFFECTS OF FLUNIXIN MEGLUMINE ON SHORT-CIRCUIT CURRENT IN EQUINE COLONIC MUCOSA IN-VITRO

Objectives-To study the effect of flunixin meglumine on short circuit current (Isc) in equine right ventral colon in vitro. Samples-Intestin al mucosa from healthy horses and ponies. Procedure-Isc was measured i n mucosa from the right ventral colon mounted in Ussing chambers. In e xperiment 1, collection and incubation solutions were: control (no add itions); flunixin meglumine, 4 mu g/ml; indomethacin, 10(-6) M; and fl unixin meglumine (4 mu g/ml) with 10(-6) M prostaglandin E-2. In exper iment 2, incubation conditions were: control (plain Krebs-Ringer bicar bonate [KRB] solution); flunixin meglumine, 4 yg/ml in KRB; chloride-f ree buffer solution, flunixin meglumine (4 mu g/ml) in a chloride-free buffer solution; and plain KRB with 10(-6) M prostaglandin E-2. In ex periment 3, tissue from 3 groups (n = 6 each) of animals: controls, ph ysiologic saline solution given IV at 10 minutes before euthanasia; fl unixin meglumine (1.1 mg/kg of body weight, IV) given at 10 minutes be fore euthanasia; and treatment similar to controls, except that tissue s were incubated with 8 mu g of flunixin meglumine/ml of bathing mediu m. Results-Flunixin meglumine and indomethacin reduced Isc to approxim ately a third of control current (P < 0.05), but coincubation with flu nixin meglumine and 10(-6) M prostaglandin E-2 restored Isc close to t he control value. Incubation with 10(-6) M prostaglandin E-2 alone did not change Isc. When chloride was substituted with isethionate, fluni xin meglumine had no effect on Isc. Flunixin meglumine given before eu thanasia or included at a concentration of 8 mu g/ml in all tissue pre paration and incubation solutions reduced Isc (P < 0.05). Conclusions- Flunixin meglumine given IV or added to bathing solutions decreased Is c in equine right ventral colon by a mechanism that appeared to involv e prostaglandin-mediated chloride secretion. Clinical Relevance-Our re sults suggest that flunixin meglumine given IV to horses at recommende d doses could alter putative effects of colonic prostaglandins.