Characterization of the hemodynamic and metabolic alterations in the large colon of horses during low-flow ischemia and reperfusion.
Abstract: Effects of low-flow ischemia and reperfusion of the large colon on systemic and colonic hemodynamic and metabolic variables were determined in horses. Twenty-four adult horses were randomly allocated to 3 groups: sham-operated (n = 6), 6 hours of ischemia (n = 9), and 3 hours of ischemia and 3 hours of reperfusion (n = 9). Low-flow ischemia was induced in groups 2 and 3 by reducing colonic arterial blood flow to 20% of baseline. Heart rate, arterial blood pressures, cardiac index, pulmonary artery pressure, right atrial pressure, and colonic blood flow were monitored. Arterial, mixed-venous, and colonic venous blood gas and oximetry analyses; PCV; and blood lactate and pyruvate and plasma total protein concentrations were measured. Data were recorded, and blood samples were collected at baseline and at 30-minute intervals for 6 hours; additionally, data were collected at 185, 190, and 195 minutes (corresponding to 5, 10, and 15 minutes of reperfusion in group-3 horses). There were no differences among groups at baseline or across time for any systemic hemodynamic or metabolic variable. Colonic blood flow did not change across time in group-1 horses. Colonic blood flow significantly (P < 0.05) decreased to 20% of baseline at induction of ischemia in horses of groups 2 and 3 and remained significantly decreased throughout the ischemic period in horses of groups 2 (6 hours) and 3 (3 hours). Colonic blood flow significantly (P < 0.05) increased above baseline by 5 minutes of reperfusion in group-3 horses. Colonic oxygen delivery and oxygen consumption, and colonic venous pH, PO2, percentage saturation of hemoglobin, and oxygen content were significantly (P < 0.05) decreased within 30 minutes after induction of ischemia in horses of groups 2 and 3; colonic venous PCO2, colonic oxygen extraction ratio, and lactate and pyruvate concentrations were significantly (P < 0.05) increased by 30 minutes of ischemia. These alterations continued throughout ischemia, but within 5 minutes of reperfusion in group-3 horses, these variables either returned to baseline (pH, PCO2, lactate, pyruvate), significantly (P < 0.05) increased above baseline (PO2, oxygen content, % saturation of hemoglobin), or significantly (P < 0.05) decreased below baseline (colonic oxygen extraction ratio). Colonic oxygen consumption remained decreased during reperfusion in group-3 horses. Colonic mucosal ischemia-reperfusion injury observed in this model of ischemia was associated with local colonic hemodynamic and metabolic alterations in the presence of systemic hemodynamic and metabolic stability.(ABSTRACT TRUNCATED AT 400 WORDS)
Publication Date: 1994-10-01 PubMed ID: 7998703
The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Clinical Trial
- Journal Article
- Randomized Controlled Trial
- Research Support
- Non-U.S. Gov't
Summary
This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.
This research studies how reduced blood flow (low-flow ischemia) and the restoration of blood flow (reperfusion) to the large colon of horses impact both systemic and colonic hemodynamic (blood flow) and metabolic processes. The study was conducted on 24 horses that were apportioned into three different groups, and metabolic parameters, such as heart rate, arterial blood pressures, and blood lactate were measured.
Methodology and Group Allocation
- The experiment was carried out on 24 adult horses that were divided into three different groups.
- The first group underwent a sham-operation, which is a procedure that mimics an operation but doesn’t include the therapeutic element. This group served as a control group.
- The second group underwent 6 hours of low-flow ischemia, which is an insufficiency of blood supply to the large colon.
- The third group experienced 3 hours of low-flow ischemia followed by 3 hours of reperfusion, the restoration of blood flow after ischemia.
- The condition of low-flow ischemia was simulated in both the second and third groups by reducing the arterial blood flow to the colon to only 20% of the normal, baseline flow.
Collection of Data
- Multiple systemic and colonic parameters were monitored, including heart rate, arterial blood pressures, cardiac index, pulmonary artery pressure, right atrial pressure, and colonic blood flow. Blood samples were collected frequently to monitor these.
- Tests performed on these samples included blood gas and oximetry analyses, packed cell volume (PCV), and measurements of blood lactate and pyruvate, and plasma total protein concentrations.
- Changes in these variables were recorded during and after ischemia and reperfusion in the respective groups.
Findings and Outcomes
- No significant changes were observed in the overall systemic hemodynamic or metabolic variables amongst the groups.
- In both low-flow ischemia groups, significant decreases (to 20% of baseline) in colonic blood flow were observed, consistent with the experiment design. This reduction persisted through the duration of the ischemic period.
- During reperfusion in the third group, the colonic blood flow significantly increased above the baseline within 5 minutes.
- Significant alterations were observed in colonic oxygen delivery and consumption, pH levels, oxygen content, and lactate and pyruvate concentrations during ischemia. Most of these variables either returned to their baseline or significantly changed within 5 minutes of reperfusion.
- However, colonic oxygen consumption remained lower than normal during reperfusion, indicating some persisting effects of ischemia.
- The investigation concludes that colonic ischemia-reperfusion injury sustained in this study exhibits local colonic hemodynamic and metabolic changes, despite systemic stability.
Cite This Article
APA
Moore RM, Muir WW, Bertone AL, Beard WL.
(1994).
Characterization of the hemodynamic and metabolic alterations in the large colon of horses during low-flow ischemia and reperfusion.
Am J Vet Res, 55(10), 1444-1453.
Publication
Researcher Affiliations
- Department of Veterinary Clinical Sciences, Ohio State University, Columbus 43210-1089.
MeSH Terms
- Animals
- Colitis, Ischemic / veterinary
- Colon / blood supply
- Colon / metabolism
- Female
- Hemodynamics
- Horse Diseases / metabolism
- Horse Diseases / physiopathology
- Horses
- Ischemia / metabolism
- Ischemia / physiopathology
- Ischemia / veterinary
- Male
- Reperfusion Injury / metabolism
- Reperfusion Injury / physiopathology
- Reperfusion Injury / veterinary
Citations
This article has been cited 2 times.- Moore RM, Sedrish SA, Holmes EP, Koch CE, Venugopal CS. Role of endothelium and nitric oxide in modulating in vitro responses of colonic arterial and venous rings to vasodilatory neuropeptides in horses. Can J Vet Res 2005 Apr;69(2):116-22.
- Moore RM, Muir WW, Rush BR. Systemic and colonic venous plasma biochemical alterations in horses during low-flow ischemia and reperfusion of the large colon. Can J Vet Res 1998 Jan;62(1):14-20.
Use Nutrition Calculator
Check if your horse's diet meets their nutrition requirements with our easy-to-use tool Check your horse's diet with our easy-to-use tool
Talk to a Nutritionist
Discuss your horse's feeding plan with our experts over a free phone consultation Discuss your horse's diet over a phone consultation
Submit Diet Evaluation
Get a customized feeding plan for your horse formulated by our equine nutritionists Get a custom feeding plan formulated by our nutritionists
