Use of an extracorporeal circuit to evaluate effects of ischemia and reperfusion of the equine large colon

Objective—To determine efficacy of an extracorporeal circuit to maintain a segment of equine large colon for 3.5 hours and to evaluate the effect of low arterial flow on histologic and metabolic variables. Sample Population—Segments of large colon from 15 healthy adult horses. Procedure—The pelvic flexure was surgically removed and maintained in an isolated circuit. In the control group, tissue was evaluated for 3.5 hours, whereas in the low-flow group, arterial flow was reduced to 20% of baseline for 40 minutes followed by 2 hours of reperfusion. Various metabolic and hemodynamic variables were evaluated at 30-minute intervals. Effects of nitric oxide (NO) and L-N-nitro-arginine- methyl-ester (L-NAME) on contractile activity were determined, and histomorphologic evaluation was performed at the completion of the study. Results—Low-flow ischemia with reperfusion caused significant histomorphologic differences, compared with the control group. In the low-flow group, significant differences included reductio...