Influence of postischemic administration of oxyradical antagonists on ischemic injury to rabbit skeletal muscle

Abstract

The aim of this study was to determine whether the administration of free radical antagonists, immediately before and during the early minutes of reperfusion, improves muscle survival 24 hr after a period of ischemia. Rabbit rectus femoris muscles were isolated, made ischemic for 3 1/2 hr and treated with either desferrioxamine (DFX), an Fe3+ chelator, superoxide dismutase and catalase (SOD & CAT), which quench superoxide and hydrogen peroxide, or allopurinol, an inhibitor of xanthine oxidase (XO). After 24 hr reperfusion, muscle viability (+/-s.e.m.), measured by the nitro blue tetrazolium (NBT) vital staining technique, was 41.6 +/- 11.3% for saline-treated ischemic controls, 30.6 +/- 7.6% for DFX-treated, 46.7 +/- 10.3% for SOD & CAT-treated, and 43.3 +/- 9.5% for allopurinol-treated muscles. None of the treated groups differed significantly from the ischemic control group. Tissue myeloperoxidase, ATP and reduced glutathione levels, and plasma lactate dehydrogenase (LDH) and aspartate transaminase (AST) levels were increased by ischemia and reperfusion in all groups, but the changes did not differ between the treatment groups. Levels of XO in the rabbit muscle were determined and found to be very low in both normal and postischemic muscle. As XO is the target enzyme of allopurinol, its absence provides a basis for the lack of effect of this agent. However, it is not clear why DFX and SOD & CAT had no protective effect.

Multimodal Strategies for Resuscitating Injured Cells

“…Loss of cell membrane integrity has been documented under many conditions besides thermal trauma as well: in frostbite injuries,10 in free‐radical mediated radiation injury,11 in barometric trauma,2,12 and in electric shock,13,14 and mechanical shear or crush forces 3,15,16. Ischemia‐reperfusion injury, which is mediated by the toxic effects of reactive oxygen species (ROS), is a common cause of membrane disruption and is an important factor in many common medical problems 11,17…”

“…Examples include protein melting (thermal denaturation) in response to higher than physiologic temperature exposure,14,23 electroconformational denaturation of ion channels and lipid bilayer electroporation following exposure to large transmembrane electrical potentials,24 and freeze‐induced protein damage 10. Loss of protein architecture can also result from exposure to reactive chemical agents such as what commonly occurs as a result of excessive intracellular generation of reactive oxygen species (ROS) 11,17. Reactive chemical injuries have in common the ability to alter the primary structure of macromolecules.…”

“…In addition, it has been shown that extracellular magnesium protects cells against energy‐dependent cell damage 55. Administration of exogenous ATP‐MgCl 2 has been shown to be beneficial for the survival of experimental animals subjected to hemorrhagic shock56,57 and ischemia 17. Moreover, ATP‐MgCl 2 has been found to improve mitochondrial function following shock and ischemia 58…”

“…3,15,16 Ischemia-reperfusion injury, which is mediated by the toxic effects of reactive oxygen species (ROS), is a common cause of membrane disruption and is an important factor in many common medical problems. 11,17 Although the effect remains the same-a defect in the cell membrane-injuries to cellular membranes can occur in many different ways. ROS mediated wounding of the cell membrane through peroxidation of phospholipids and the oxidative deamination of membrane proteins.…”

“…10 Loss of protein architecture can also result from exposure to reactive chemical agents such as what commonly occurs as a result of excessive intracellular generation of reactive oxygen species (ROS). 11,17 Reactive chemical injuries have in common the ability to alter the primary structure of macromolecules. In comparison to thermal burn and electrical injury, the major damaging effect on cells from ionizing radiation injury are initiated at the primary protein structure level.…”