Journal of Applied Physiology, Vol 75, Issue 5 2180-2187, Copyright © 1993 by American Physiological Society

ARTICLES

Effect of ischemia-reperfusion on diaphragm strength and fatigability

G. Supinski, D. Stofan and A. DiMarco
Department of Medicine, Case Western Reserve University, Cleveland, Ohio 44106.

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)

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