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

Intestinal mucosa from healthy horses and ponies.

PROCEDURE

Isc was measured in mucosa from the right ventral colon mounted in Ussing chambers. In experiment 1, collection and incubation solutions were: control (no additions); flunixin meglumine, 4 micrograms/ml; indomethacin, 10(-6) M; and flunixin meglumine (4 micrograms/ml) with 10(-6) M prostaglandin E2. In experiment 2, incubation conditions were: control [plain Krebs-Ringer bicarbonate [KRB] solution]; flunixin meglumine, 4 micrograms/ml in KRB; chloride-free buffer solution; flunixin meglumine (4 micrograms/ml) in a chloride-free buffer solution; and plain KRB with 10(-6) M prostaglandin E2. In experiment 3, tissue from 3 groups (n = 6 each) of animals: controls, physiologic saline solution given IV at 10 minutes before euthanasia; flunixin meglumine (1.1 mg/kg of body weight, IV) given at 10 minutes before euthanasia; and treatment similar to controls, except that tissues were incubated with 8 micrograms of flunixin meglumine/ml of bathing medium.

RESULTS

Flunixin meglumine and indomethacin reduced Isc to approximately a third of control current (P < 0.05), but coincubation with flunixin meglumine and 10(-5) M prostaglandin E2 restored Isc close to the control value. Incubation with 10(-6) M prostaglandin E2 alone did not change Isc. When chloride was substituted with isethionate, flunixin meglumine had no effect on Isc. Flunixin meglumine given before euthanasia or included at a concentration of 8 micrograms/ml in all tissue preparation and incubation solutions reduced Isc (P < 0.05).

CONCLUSIONS

Flunixin meglumine given IV or added to bathing solutions decreased Isc in equine right ventral colon by a mechanism that appeared to involve prostaglandin-mediated chloride secretion.

CLINICAL RELEVANCE

Our results suggest that flunixin meglumine given IV to horses at recommended doses could alter putative effects of colonic prostaglandins.