Effect of ischemia-reperfusion on diaphragm strength and fatigability.
Although episodes of prolonged limb skeletal muscle ischemia followed by periods of reperfusion and reoxygenation are known to elicit free radical-mediated injury, the susceptibility of the diaphragm to this form of injury is not known. The purpose of the present study was to determine the effects of a period of severe partial ischemia, followed by reperfusion, on diaphragm contractile function. We also examined the effect of administration of a free radical scavenger, dimethyl sulfoxide (DMSO), on the diaphragmatic response to ischemia-reperfusion. Experiments were performed on three groups of anesthetized dogs in which a vascularly isolated strip of diaphragm was dissected in situ: 1) a control group in which the diaphragm was perfused at the ambient systemic pressure, 2) a group in which the diaphragm was made ischemic for 3 h and reperfused for 1 h, and 3) a group given DMSO before periods of ischemia and reperfusion. In all groups, we measured diaphragm strip strength and fatigability; we also assessed diaphragm blood flow at several levels of contractile activity. Periods of ischemia, followed by reperfusion, were found to produce a downward shift of the diaphragm force-frequency relationship and also to markedly increase diaphragm fatigability. Diaphragm blood flow at rest and at low levels of contractile activity was unaffected by ischemia-reperfusion, but the flow achieved during fatiguing contractions was appreciably lower than that in nonischemic control animals. DMSO administration protected the diaphragm from the effects of ischemia-reperfusion, preventing alterations in fatigability and strength. Diaphragm flow in DMSO-treated animals was similar to that in controls.(ABSTRACT TRUNCATED AT 250 WORDS)
Supinski
G
G
Department of Medicine, Case Western Reserve University, Cleveland, Ohio 44106.
Stofan
D
D
DiMarco
A
A
D000818:Animals; D003964:Diaphragm / Q000098:blood supply / Q000503:physiopathology*; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D004285:Dogs; D005260:Female; D066298:In Vitro Techniques; D007511:Ischemia / Q000503:physiopathology*; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D012039:Regional Blood Flow / Q000502:physiology; D015427:Reperfusion Injury / Q000503:physiopathology*
D004121:Dimethyl Sulfoxide