The effects of systemic hypoxia on colon anastomotic healing

An animal model

Jo Anne P Attard, Manoj J. Raval, Gary R. Martin, Jon Kolb, Marjan Afrouzian, W. Donald Buie, David L. Sigalet

Research output: Contribution to journalArticle

61 Citations (Scopus)

Abstract

PURPOSE: Acute postoperative systemic hypoxia occurs frequently in the clinical setting following intestinal resection, as a result of complications such as pneumonia, pulmonary edema, or the acute respiratory distress syndrome. Although it is well established that oxygen is essential for metabolism in general and intestinal anastomotic healing, the mechanisms by which systemic hypoxia affect this process are not clear. The purpose of this study was to establish an animal model to simulate acute systemic hypoxia and to examine the effects on anastomotic healing. We investigated the hypothesis that systemic hypoxia impairs anastomotic healing in the colon by disrupting revascularization via changes in the expression of two putative angiogenic factors: inducible nitric oxide synthase and vascular endothelial growth factor. METHODS: Phase I: Juvenile male Sprague-Dawley rats underwent carotid artery cannulation. In a controlled environment the FiO2 was incrementally decreased from 21 to 9 percent and the resultant PaO2 measured. Phase II: Animals underwent colonic transection with immediate reanastomosis and were placed in either a normoxic (FiO2 21 percent) or hypoxic (FiO2 11 percent) environment for seven days. Perianastomotic in vivo tissue oxygen saturation was measured before segmental colon resection in each of the animals and at seven days before measurement of anastomotic bursting pressure. Perianastomotic tissue samples were assessed by Western blot assay for the expression of vascular endothelial growth factor and inducible nitric oxide synthase protein. Sections from each tissue sample were taken and evaluated by a pathologist blinded to treatment group for determination of anastomotic healing score. RESULTS: Phase I: Incrementally decreasing the FiO2 resulted in a progressive decrease in PaO2 (r 2 = 0.77). Phase II: Animals maintained in a hypoxic environment had a significant decrease in tissue oxygen saturation (73 ± 9 percent vs. 94 ± 3 percent; P < 0.0001) and anastomotic bursting pressure (118 ± 18 mmHg vs. 207 ± 30 mmHg; P < 0.0001) compared with normoxic controls. Systemic hypoxia induced a significant increase, when compared with normoxic controls, in vascular endothelial growth factor (247.1 ± 9.5 vs. 142.2 ± 10.6; P < 0.0001) and inducible nitric oxide synthase (259.6 ± 21.1 vs. 120.2 ± 10.9; P < 0.0001) protein expression and led to a significant decrease in the overall wound-healing score. CONCLUSION: This study validates a new animal model to study the effects of acute systemic hypoxia on colonic anastomotic healing. In this model, systemic hypoxia directly translated into local tissue hypoxia, and anastomotic healing was impaired. Contrary to our original hypothesis, hypoxia led to a significant increase in vascular endothelial growth factor and inducible nitric oxide synthase protein expression at the colonic anastomotic site. Impairment in anastomotic integrity despite upregulation of these angiogenic factors could be a result of the inability of wounded tissue to respond to vascular endothelial growth factor and inducible nitric oxide synthase or alternatively, hypoxia may adversely affect collagen synthesis and deposition directly.

Original languageEnglish (US)
Pages (from-to)1460-1470
Number of pages11
JournalDiseases of the Colon and Rectum
Volume48
Issue number7
DOIs
StatePublished - Jul 2005
Externally publishedYes

Fingerprint

Colon
Animal Models
Nitric Oxide Synthase Type II
Vascular Endothelial Growth Factor A
Angiogenesis Inducing Agents
Oxygen
Hypoxia
Pressure
Controlled Environment
Proteins
Adult Respiratory Distress Syndrome
Pulmonary Edema
Carotid Arteries
Catheterization
Wound Healing
Sprague Dawley Rats
Pneumonia
Up-Regulation
Collagen
Western Blotting

Keywords

  • Anastomosis
  • Angiogenesis
  • Colon
  • Hypoxia
  • Nitric oxide synthase
  • Surgical
  • Vascular endothelial growth factor
  • Wound healing

ASJC Scopus subject areas

  • Gastroenterology

Cite this

Attard, J. A. P., Raval, M. J., Martin, G. R., Kolb, J., Afrouzian, M., Buie, W. D., & Sigalet, D. L. (2005). The effects of systemic hypoxia on colon anastomotic healing: An animal model. Diseases of the Colon and Rectum, 48(7), 1460-1470. https://doi.org/10.1007/s10350-005-0047-3

The effects of systemic hypoxia on colon anastomotic healing : An animal model. / Attard, Jo Anne P; Raval, Manoj J.; Martin, Gary R.; Kolb, Jon; Afrouzian, Marjan; Buie, W. Donald; Sigalet, David L.

In: Diseases of the Colon and Rectum, Vol. 48, No. 7, 07.2005, p. 1460-1470.

Research output: Contribution to journalArticle

Attard, JAP, Raval, MJ, Martin, GR, Kolb, J, Afrouzian, M, Buie, WD & Sigalet, DL 2005, 'The effects of systemic hypoxia on colon anastomotic healing: An animal model', Diseases of the Colon and Rectum, vol. 48, no. 7, pp. 1460-1470. https://doi.org/10.1007/s10350-005-0047-3
Attard, Jo Anne P ; Raval, Manoj J. ; Martin, Gary R. ; Kolb, Jon ; Afrouzian, Marjan ; Buie, W. Donald ; Sigalet, David L. / The effects of systemic hypoxia on colon anastomotic healing : An animal model. In: Diseases of the Colon and Rectum. 2005 ; Vol. 48, No. 7. pp. 1460-1470.
@article{9795d38a92554be581507ef79362c0a6,
title = "The effects of systemic hypoxia on colon anastomotic healing: An animal model",
abstract = "PURPOSE: Acute postoperative systemic hypoxia occurs frequently in the clinical setting following intestinal resection, as a result of complications such as pneumonia, pulmonary edema, or the acute respiratory distress syndrome. Although it is well established that oxygen is essential for metabolism in general and intestinal anastomotic healing, the mechanisms by which systemic hypoxia affect this process are not clear. The purpose of this study was to establish an animal model to simulate acute systemic hypoxia and to examine the effects on anastomotic healing. We investigated the hypothesis that systemic hypoxia impairs anastomotic healing in the colon by disrupting revascularization via changes in the expression of two putative angiogenic factors: inducible nitric oxide synthase and vascular endothelial growth factor. METHODS: Phase I: Juvenile male Sprague-Dawley rats underwent carotid artery cannulation. In a controlled environment the FiO2 was incrementally decreased from 21 to 9 percent and the resultant PaO2 measured. Phase II: Animals underwent colonic transection with immediate reanastomosis and were placed in either a normoxic (FiO2 21 percent) or hypoxic (FiO2 11 percent) environment for seven days. Perianastomotic in vivo tissue oxygen saturation was measured before segmental colon resection in each of the animals and at seven days before measurement of anastomotic bursting pressure. Perianastomotic tissue samples were assessed by Western blot assay for the expression of vascular endothelial growth factor and inducible nitric oxide synthase protein. Sections from each tissue sample were taken and evaluated by a pathologist blinded to treatment group for determination of anastomotic healing score. RESULTS: Phase I: Incrementally decreasing the FiO2 resulted in a progressive decrease in PaO2 (r 2 = 0.77). Phase II: Animals maintained in a hypoxic environment had a significant decrease in tissue oxygen saturation (73 ± 9 percent vs. 94 ± 3 percent; P < 0.0001) and anastomotic bursting pressure (118 ± 18 mmHg vs. 207 ± 30 mmHg; P < 0.0001) compared with normoxic controls. Systemic hypoxia induced a significant increase, when compared with normoxic controls, in vascular endothelial growth factor (247.1 ± 9.5 vs. 142.2 ± 10.6; P < 0.0001) and inducible nitric oxide synthase (259.6 ± 21.1 vs. 120.2 ± 10.9; P < 0.0001) protein expression and led to a significant decrease in the overall wound-healing score. CONCLUSION: This study validates a new animal model to study the effects of acute systemic hypoxia on colonic anastomotic healing. In this model, systemic hypoxia directly translated into local tissue hypoxia, and anastomotic healing was impaired. Contrary to our original hypothesis, hypoxia led to a significant increase in vascular endothelial growth factor and inducible nitric oxide synthase protein expression at the colonic anastomotic site. Impairment in anastomotic integrity despite upregulation of these angiogenic factors could be a result of the inability of wounded tissue to respond to vascular endothelial growth factor and inducible nitric oxide synthase or alternatively, hypoxia may adversely affect collagen synthesis and deposition directly.",
keywords = "Anastomosis, Angiogenesis, Colon, Hypoxia, Nitric oxide synthase, Surgical, Vascular endothelial growth factor, Wound healing",
author = "Attard, {Jo Anne P} and Raval, {Manoj J.} and Martin, {Gary R.} and Jon Kolb and Marjan Afrouzian and Buie, {W. Donald} and Sigalet, {David L.}",
year = "2005",
month = "7",
doi = "10.1007/s10350-005-0047-3",
language = "English (US)",
volume = "48",
pages = "1460--1470",
journal = "Diseases of the Colon and Rectum",
issn = "0012-3706",
publisher = "Lippincott Williams and Wilkins",
number = "7",

}

TY - JOUR

T1 - The effects of systemic hypoxia on colon anastomotic healing

T2 - An animal model

AU - Attard, Jo Anne P

AU - Raval, Manoj J.

AU - Martin, Gary R.

AU - Kolb, Jon

AU - Afrouzian, Marjan

AU - Buie, W. Donald

AU - Sigalet, David L.

PY - 2005/7

Y1 - 2005/7

N2 - PURPOSE: Acute postoperative systemic hypoxia occurs frequently in the clinical setting following intestinal resection, as a result of complications such as pneumonia, pulmonary edema, or the acute respiratory distress syndrome. Although it is well established that oxygen is essential for metabolism in general and intestinal anastomotic healing, the mechanisms by which systemic hypoxia affect this process are not clear. The purpose of this study was to establish an animal model to simulate acute systemic hypoxia and to examine the effects on anastomotic healing. We investigated the hypothesis that systemic hypoxia impairs anastomotic healing in the colon by disrupting revascularization via changes in the expression of two putative angiogenic factors: inducible nitric oxide synthase and vascular endothelial growth factor. METHODS: Phase I: Juvenile male Sprague-Dawley rats underwent carotid artery cannulation. In a controlled environment the FiO2 was incrementally decreased from 21 to 9 percent and the resultant PaO2 measured. Phase II: Animals underwent colonic transection with immediate reanastomosis and were placed in either a normoxic (FiO2 21 percent) or hypoxic (FiO2 11 percent) environment for seven days. Perianastomotic in vivo tissue oxygen saturation was measured before segmental colon resection in each of the animals and at seven days before measurement of anastomotic bursting pressure. Perianastomotic tissue samples were assessed by Western blot assay for the expression of vascular endothelial growth factor and inducible nitric oxide synthase protein. Sections from each tissue sample were taken and evaluated by a pathologist blinded to treatment group for determination of anastomotic healing score. RESULTS: Phase I: Incrementally decreasing the FiO2 resulted in a progressive decrease in PaO2 (r 2 = 0.77). Phase II: Animals maintained in a hypoxic environment had a significant decrease in tissue oxygen saturation (73 ± 9 percent vs. 94 ± 3 percent; P < 0.0001) and anastomotic bursting pressure (118 ± 18 mmHg vs. 207 ± 30 mmHg; P < 0.0001) compared with normoxic controls. Systemic hypoxia induced a significant increase, when compared with normoxic controls, in vascular endothelial growth factor (247.1 ± 9.5 vs. 142.2 ± 10.6; P < 0.0001) and inducible nitric oxide synthase (259.6 ± 21.1 vs. 120.2 ± 10.9; P < 0.0001) protein expression and led to a significant decrease in the overall wound-healing score. CONCLUSION: This study validates a new animal model to study the effects of acute systemic hypoxia on colonic anastomotic healing. In this model, systemic hypoxia directly translated into local tissue hypoxia, and anastomotic healing was impaired. Contrary to our original hypothesis, hypoxia led to a significant increase in vascular endothelial growth factor and inducible nitric oxide synthase protein expression at the colonic anastomotic site. Impairment in anastomotic integrity despite upregulation of these angiogenic factors could be a result of the inability of wounded tissue to respond to vascular endothelial growth factor and inducible nitric oxide synthase or alternatively, hypoxia may adversely affect collagen synthesis and deposition directly.

AB - PURPOSE: Acute postoperative systemic hypoxia occurs frequently in the clinical setting following intestinal resection, as a result of complications such as pneumonia, pulmonary edema, or the acute respiratory distress syndrome. Although it is well established that oxygen is essential for metabolism in general and intestinal anastomotic healing, the mechanisms by which systemic hypoxia affect this process are not clear. The purpose of this study was to establish an animal model to simulate acute systemic hypoxia and to examine the effects on anastomotic healing. We investigated the hypothesis that systemic hypoxia impairs anastomotic healing in the colon by disrupting revascularization via changes in the expression of two putative angiogenic factors: inducible nitric oxide synthase and vascular endothelial growth factor. METHODS: Phase I: Juvenile male Sprague-Dawley rats underwent carotid artery cannulation. In a controlled environment the FiO2 was incrementally decreased from 21 to 9 percent and the resultant PaO2 measured. Phase II: Animals underwent colonic transection with immediate reanastomosis and were placed in either a normoxic (FiO2 21 percent) or hypoxic (FiO2 11 percent) environment for seven days. Perianastomotic in vivo tissue oxygen saturation was measured before segmental colon resection in each of the animals and at seven days before measurement of anastomotic bursting pressure. Perianastomotic tissue samples were assessed by Western blot assay for the expression of vascular endothelial growth factor and inducible nitric oxide synthase protein. Sections from each tissue sample were taken and evaluated by a pathologist blinded to treatment group for determination of anastomotic healing score. RESULTS: Phase I: Incrementally decreasing the FiO2 resulted in a progressive decrease in PaO2 (r 2 = 0.77). Phase II: Animals maintained in a hypoxic environment had a significant decrease in tissue oxygen saturation (73 ± 9 percent vs. 94 ± 3 percent; P < 0.0001) and anastomotic bursting pressure (118 ± 18 mmHg vs. 207 ± 30 mmHg; P < 0.0001) compared with normoxic controls. Systemic hypoxia induced a significant increase, when compared with normoxic controls, in vascular endothelial growth factor (247.1 ± 9.5 vs. 142.2 ± 10.6; P < 0.0001) and inducible nitric oxide synthase (259.6 ± 21.1 vs. 120.2 ± 10.9; P < 0.0001) protein expression and led to a significant decrease in the overall wound-healing score. CONCLUSION: This study validates a new animal model to study the effects of acute systemic hypoxia on colonic anastomotic healing. In this model, systemic hypoxia directly translated into local tissue hypoxia, and anastomotic healing was impaired. Contrary to our original hypothesis, hypoxia led to a significant increase in vascular endothelial growth factor and inducible nitric oxide synthase protein expression at the colonic anastomotic site. Impairment in anastomotic integrity despite upregulation of these angiogenic factors could be a result of the inability of wounded tissue to respond to vascular endothelial growth factor and inducible nitric oxide synthase or alternatively, hypoxia may adversely affect collagen synthesis and deposition directly.

KW - Anastomosis

KW - Angiogenesis

KW - Colon

KW - Hypoxia

KW - Nitric oxide synthase

KW - Surgical

KW - Vascular endothelial growth factor

KW - Wound healing

UR - http://www.scopus.com/inward/record.url?scp=21644440907&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=21644440907&partnerID=8YFLogxK

U2 - 10.1007/s10350-005-0047-3

DO - 10.1007/s10350-005-0047-3

M3 - Article

VL - 48

SP - 1460

EP - 1470

JO - Diseases of the Colon and Rectum

JF - Diseases of the Colon and Rectum

SN - 0012-3706

IS - 7

ER -