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Effects of adenosine pretreatment on detection of free radicals in ischemic and reperfused canine gracilis muscle flaps by use of spin-trapping electron paramagnetic resonance spectroscopy

Brigitte A. Brisson DMV, DVSc1, Craig W. Miller DVM, MVSc2, Guoman Chen PhD3, L. Jill McCutcheon DVM, PhD4, and Edward G. Janzen PhD5
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  • 1 Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada N1G 2W1.
  • | 2 Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada N1G 2W1.
  • | 3 Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada N1G 2W1.
  • | 4 Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada N1G 2W1.
  • | 5 Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada N1G 2W1.

Abstract

Objective—To determine whether adenosine pretreatment attenuates free radical production and muscle damage in ischemic and reperfused canine skeletal muscle.

Animals—9 healthy mixed-breed dogs.

Procedure—Dogs were anesthetized, and both gracilis muscles were isolated, leaving only the major vascular pedicle intact. Saline (0.9% NaCl) solution was injected into the artery supplying the control flap, whereas adenosine (10 mg) was injected into the contralateral artery. Ischemia was induced in both flaps for 4 hours. α-Phenyl-N-tert-butylnitrone was administered IV to each dog 1 hour prior to reperfusion. Following 15 minutes of reperfusion, effluent blood samples from each muscle flap were obtained and processed for spin-trapping electron paramagnetic resonance (EPR) spectroscopy. Muscle biopsy specimens were obtained for histologic evaluation, and dogs were euthanatized.

Results—EPR spectra of strong intensity were obtained from analysis of 5 of 9 paired samples. Signals identified were characteristic of oxygen- and carbon-centered free radical adducts. Signal intensity of spectra from adenosine-treated flaps was significantly less than that of control flaps; mean signal attenuation was 36% in the adenosine-treated group. Histologic evaluation of muscle flaps did not reveal significant differences between groups.

Conclusions and Clinical Relevance—Treatment of canine muscle flaps with adenosine prior to a period of ischemia reduced but did not completely attenuate free radical production after reperfusion. However, adenosine pretreatment did not affect histologic abnormalities. (Am J Vet Res 2002;63:175–180)

Abstract

Objective—To determine whether adenosine pretreatment attenuates free radical production and muscle damage in ischemic and reperfused canine skeletal muscle.

Animals—9 healthy mixed-breed dogs.

Procedure—Dogs were anesthetized, and both gracilis muscles were isolated, leaving only the major vascular pedicle intact. Saline (0.9% NaCl) solution was injected into the artery supplying the control flap, whereas adenosine (10 mg) was injected into the contralateral artery. Ischemia was induced in both flaps for 4 hours. α-Phenyl-N-tert-butylnitrone was administered IV to each dog 1 hour prior to reperfusion. Following 15 minutes of reperfusion, effluent blood samples from each muscle flap were obtained and processed for spin-trapping electron paramagnetic resonance (EPR) spectroscopy. Muscle biopsy specimens were obtained for histologic evaluation, and dogs were euthanatized.

Results—EPR spectra of strong intensity were obtained from analysis of 5 of 9 paired samples. Signals identified were characteristic of oxygen- and carbon-centered free radical adducts. Signal intensity of spectra from adenosine-treated flaps was significantly less than that of control flaps; mean signal attenuation was 36% in the adenosine-treated group. Histologic evaluation of muscle flaps did not reveal significant differences between groups.

Conclusions and Clinical Relevance—Treatment of canine muscle flaps with adenosine prior to a period of ischemia reduced but did not completely attenuate free radical production after reperfusion. However, adenosine pretreatment did not affect histologic abnormalities. (Am J Vet Res 2002;63:175–180)