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.


METHODS
Segments of large colon from 15 healthy adult horses.


METHODS
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 reduction in PaCO2, reduction in bicarbonate concentrations, increase in PaO2, and an increase in base deficit in arterial and venous blood samples. Other significant differences included increases in PCV, protein concentration, total WBC count, and albumin clearance for the low-flow group. Differences were not detected in inhibitory activity of the low-flow group relative to the control tissue with or without addition of NO and L-NAME.


CONCLUSIONS
The extracorporeal circuit maintained a segment of equine intestine for 3.5 hours and can be used to simulate ischemic injury. The extracorporeal circuit provides the potential to investigate pharmaceutic agents that can minimize intestinal injury.
Van Hoogmoed
L M
LM
Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis 95616, USA.
Snyder
J R
JR
Nieto
J E
JE
Vatistas
N J
NJ
Harmon
F A
FA
D000818:Animals; D001784:Blood Gas Analysis / Q000662:veterinary; D002245:Carbon Dioxide / Q000097:blood; D003106:Colon / Q000098:blood supply*; D005112:Extracorporeal Circulation / Q000662:veterinary*; D005260:Female; D006734:Horse Diseases / Q000503:physiopathology*; D006736:Horses; D007413:Intestinal Mucosa / Q000378:metabolism; D007511:Ischemia / Q000503:physiopathology / Q000662:veterinary*; D007958:Leukocyte Count; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000494:pharmacology; D010100:Oxygen / Q000097:blood; D015427:Reperfusion Injury / Q000662:veterinary*
D002245:Carbon Dioxide; D009569:Nitric Oxide; D010100:Oxygen; D019331:NG-Nitroarginine Methyl Ester