Effect of high-molecular weight dextran macromolecules on low-flow ischemia and reperfusion of the large colon in horses.
OBJECTIVE
To evaluate the effect of high-molecular weight (MW) dextran macromolecules on low-flow ischemia and reperfusion of the large colon in horses.


METHODS
Horses subjected to low-flow ischemia and reperfusion of the large colon were treated with either 0.9 NaCl (group 1, n = 6) or high-MW dextran (group 2, n = 6) solutions.


METHODS
12 adults horses.


METHODS
Horses were subjected to 3 hours' low-flow ischemia followed by 3 hours' reperfusion. A dose of either 0.9% NaCl or a 6% solution of high-MW (250,000) dextran (10 ml/kg of body weight) was administered i.v., 30 minutes prior to reperfusion. Hemodynamic variables were recorded at 30-minute intervals. Systemic arterial and colonic venous blood were collected for determination of PCV, plasma total protein, and whole blood lactate concentrations, and for blood gas and oximetry analyses. Histologic examination of large-colon biopsy specimens was performed.


RESULTS
Mean arterial pressure was greater in group-2 horses, compared with group-1 horses, from 3 to 3.25 hours, but there were no significant differences between groups for any of the other hemodynamic variables. Compared with baseline values, colonic blood flow was significantly lower from 0.5 to 3 hours and was significantly greater from 3.25 to 6 hours. Arterial and colonic venous PCV were significantly lower than baseline values from 3 to 3.25 hours, and at 3 hours, respectively, in group-2 horses. These values were significantly lower in group-2 horses, from 3 to 6 and 3 to 5 hours, respectively. There was significant mucosal necrosis, hemorrhage, edema, and neutrophil infiltration in horses of both groups; however, there were no significant differences between the 2 groups.


CONCLUSIONS
High-MW dextran did not protect the colonic mucosa from low-flow ischemia and reperfusion; there were no deleterious effects on colonic mucosa or on systemic hemodynamic or metabolic variables.


CONCLUSIONS
Reperfusion with high-MW dextran solution probably would not protect the large colon from ischemia-reperfusion injury associated with large-colon volvulus.
Moore
R M
RM
Department of Veterinary Clinical Sciences, Ohio State University, Columbus 43210-1089, USA.
Bertone
A L
AL
Muir
W W
WW
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001798:Blood Proteins / Q000378:metabolism; D003106:Colon / Q000098:blood supply*; D003911:Dextrans / Q000494:pharmacology*; D006736:Horses; D006863:Hydrogen-Ion Concentration; D007413:Intestinal Mucosa / Q000098:blood supply* / Q000473:pathology; D007511:Ischemia / Q000097:blood / Q000503:physiopathology*; D009130:Muscle, Smooth / Q000098:blood supply; D010092:Oximetry; D010100:Oxygen / Q000097:blood; D010108:Oxyhemoglobins / Q000378:metabolism; D012039:Regional Blood Flow / Q000187:drug effects; D015424:Reperfusion; D013997:Time Factors
D001798:Blood Proteins; D003911:Dextrans; D010108:Oxyhemoglobins; D010100:Oxygen