Alterations in colonic arterial and venous plasma neuropeptide concentrations in horses during low-flow ischemia and reperfusion of the large colon.
Abstract: To measure colonic arterial (CA) and colonic venous (CV) plasma neuropeptide concentrations during low-flow ischemia and reperfusion of the large colon in horses. Methods: 10 adult horses. Methods: CA and CV plasma samples collected from anesthetized horses during experimentally induced low-flow colonic ischemia and reperfusion were assayed for vasoactive intestinal polypeptide (VIP), calcitonin gene-related peptide (CGRP), and substance P (SP), using radioimmunoassays. In 6 anesthetized horses, colonic ischemia (20% of baseline (BL]) was maintained for 3 hours, then blood flow was restored and monitored for 3 hours. Hemodynamic variables were monitored continuously and recorded at 30-minute intervals. CA resistance was calculated from colonic blood flow (Q(colon)) and mean CA pressure values at each time. Blood was obtained from CA and CV catheters at 0, 1, 2, 3, 3.25, 3.5, 4, 5, and 6 hours; plasma VIP, CGRP, and SP concentrations were quantified, using radioimmunoassays. In 4 additional horses, VIP and CGRP were measured in CA and CV blood at 0, 0.25, 0.5, 0.75, and 1 hour. Results: Heart rate was significantly increased at 5.5 and 6 hours; other alterations in systemic hemodynamic variables were not significant. Decrease in Q(colon) during ischemia was significant; Q(colon) rebounded to a value significantly greater than BL value within 5 minutes of reperfusion and was maintained above the BL value during 3 hours of reperfusion. Mean CA pressure was significantly decreased during ischemia, but returned to a value not different from the BL value by 3.25 hours. Mean CV pressure remained unchanged from the BL value during ischemia, but increased to a value significantly greater than the BL value by 3.25 hours and remained increased through 6 hours. CA resistance began to decrease during early ischemia and was significantly less than the BL value by 3.25 hours; it remained less than the BL value through 4 hours. Increase in CV VIP concentration was significant by 0.25 hour of ischemia, but decreased to a value not different from BL value by 3.25 hours. Increase in CV CGRP was significant at 3.25 hours, but this variable returned to a value not different from BL value by 3.5 hours. Conclusions: CV VIP concentration increases during low-flow colonic ischemia, and CV and CA CGRP and CA SP concentrations increase during early reperfusion.
Publication Date: 1996-08-01 PubMed ID: 8836375
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This study investigates how the concentrations of certain neuropeptides in the blood change in horses when the large colon experiences periods of reduced blood flow, also known as ischemia, followed by restoring of blood flow or reperfusion. The neuropeptides being studied include Vasoactive Intestinal Peptide (VIP), Calcitonin Gene-related Peptide (CGRP), and Substance P (SP), which are present in the blood flowing to and from the colon.
Research Design and Methodology
- The experiment was conducted on ten adult horses that were anesthetized.
- In six of these horses, colonic ischemia was experimentally induced by reducing blood flow to the large colon to 20 percent of normal (marked as baseline, or BL) and maintained it at this level for three hours. Then the blood flow was restored and monitored for another three hours.
- Different physiological variables including heart rate and colonic arterial pressure were continuously monitored and recorded every 30 minutes.
- Blood samples were collected from both colonic arteries (CA) and colonic veins (CV) at fixed intervals during the ischemia and reperfusion. The plasma extracted from these samples was used to measure concentrations of VIP, CGRP, and SP using a technique called radioimmunoassays.
- In another group of four horses, only the VIP and CGRP levels in blood from CA and CV were measured, at shorter intervals during the first hour of the experiment.
Results and Findings
- Heart rate saw a significant increase at the 5.5 and 6 hour marks of the experiment, but changes in other systemic hemodynamic variables were not statistically significant.
- During the ischemia phase, a significant decrease in blood flow to the colon was observed. When blood flow was restored (reperfusion), it was observed to rebound to an amount significantly more than the baseline value within 5 minutes, and this elevated level was maintained throughout the rest of the reperfusion period of three hours.
- Colonic arterial pressure dropped significantly during ischemia, but it returned to baseline value by 3.25 hours after reperfusion began.
- Colonic venous pressure did not change during the ischemia phase, but it increased significantly past the baseline after 3.25 hours into reperfusion, and stayed elevated for the rest of the experiment.
- Concentrations of VIP in the CV were significantly increased by as early as 0.25 hours into ischemia, but it returned to baseline value by 3.25 hours into reperfusion.
- Levels of CGRP in the CV increased noticeably at 3.25 hours into ischemia, but returned to baseline value by 3.5 hours into reperfusion.
Conclusion
The research showed that during a period of reduced blood flow (ischemia) in the large colon of horses, there is an increase in the concentration of the neuropeptide VIP in the blood from the colonic vein (CV). Later when blood flow is restored (reperfusion), the concentrations of both the CGRP and SP neuropeptides were observed to increase in blood from both colonic artery (CA) and vein. This study provides valuable insights into the impacts of ischemia and reperfusion on the neuropeptide concentrations and could be pivotal for the understanding of equine colic conditions.
Cite This Article
APA
Moore RM, Charalambous AC, Masty J.
(1996).
Alterations in colonic arterial and venous plasma neuropeptide concentrations in horses during low-flow ischemia and reperfusion of the large colon.
Am J Vet Res, 57(8), 1200-1205.
Publication
Researcher Affiliations
- Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge 70803-8410, USA.
MeSH Terms
- Animals
- Arteries
- Blood Pressure
- Calcitonin Gene-Related Peptide / blood
- Cardiac Output
- Colon / blood supply
- Colon / physiopathology
- Heart Rate
- Hemodynamics
- Horses
- Ischemia / blood
- Ischemia / physiopathology
- Muscle, Smooth / blood supply
- Muscle, Smooth / physiopathology
- Neuropeptides / blood
- Radioimmunoassay
- Regional Blood Flow
- Reperfusion
- Substance P / blood
- Time Factors
- Vasoactive Intestinal Peptide / blood
- Veins
Citations
This article has been cited 3 times.- Haywood LMB, Sheahan BJ. A Review of Epithelial Ion Transporters and Their Roles in Equine Infectious Colitis. Vet Sci 2024 Oct 7;11(10).
- Sharifi K, Mostaghni K, Maleki M, Badiei K. Ischaemia/reperfusion injury in experimentally induced abomasal volvulus in sheep. Vet Res Commun 2007 Jul;31(5):575-90.
- 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.
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