Effects of dexamethasone on the contractile function of reperfused skeletal muscle

Abstract

This study evaluated the effects of dexamethasone (DXM) on contractile function of reperfused extensor digitalis longus (EDL) muscles following 3-hour ischemia and 24-hour reperfusion. The rats were divided into four groups: normal muscle, ischemia with saline treatment, ischemia/reperfusion with saline treatment, and ischemia/reperfusion with DXM treatment groups. DXM (0.6 mg kg −1 ) or saline (3.0 ml kg −1 ) was administered at 3 hours prior to ischemia. Results showed that although contractile force in all three treated groups was significantly lower than that of normal EDL, the average isometric tetanic contractile force in the DXMtreated group was significantly greater than that in the salinetreated ischemia and ischemia/reperfusion groups. A significant difference was also seen at the peak force and at 5 seconds of the fatigue trains, and with a longer fatigue halftime (FT 1/2 ) in the DXM-treated group than in the other two groups. Histologically, edema, inflammation and necrosis of muscle fiber were less severe in the DXM-treated group than in the saline-treated group. The results indicate that pretreatment with DXM appears to attenuate, but does not completely reverse, the contractile function deficit of ischemic skeletal muscle during the first 24 hours of reperfusion.

Effect of a Nitric Oxide Donor on Microcirculation of Acutely Denervated Skeletal Muscle during Reperfusion

“…5,6 We have validated the protective effect of an exogenous NO donor, s-nitroson-acetylcysteine (SNAC), against I/R injury in an innervated skeletal muscle model. 7,8 Because the tissue is functionally denervated in most clinical cases involving free tissue transfer and replantation, this study was designed to determine further if SNAC provides the same protective effect on denervated skeletal muscle following I/R.…”

Dexamethasone promotes long‐term functional recovery of neuromuscular junction in a murine model of tourniquet‐induced ischaemia–reperfusion

“…Some previous studies demonstrated that one‐time treatment with Dex successfully attenuated acute IR (2.5‐ or 3‐h ischaemia and 24‐h reperfusion) injury of the skeletal muscle including skeletal muscle viability and skeletal muscle contractile dysfunction (Chen et al . , Knight et al . ).…”

“…Summarizing these results, we consider that treatment with Dex through the entire course of the first 7 days is necessary to improve long‐term recovery of IR‐injured NMJ and skeletal muscles, although one‐time treatment with Dex has blunted acute IR injury of the skeletal muscle in other studies (Chen et al . , Knight et al . ).…”

“…Additionally, in the animal model of hindlimb IR injury, treatment with Dex successfully rescued IR‐induced skeletal muscle contractile dysfunction (Chen et al . ), improved skeletal muscle viability (Knight et al . ) and increased animal survival rate in the early stage of reperfusion (Murata et al .…”

Avoiding long‐term muscle damage upon ischaemia–reperfusion

“…Animal models for tourniquet effects were set up and largely reproduced human symptoms, such as deficits in contractile strength and neurological features (Chen et al . , Knight et al . , Mohler et al .…”