E19K FREE COMMUNICATION/POSTER ECCENTRIC CONTRACTIONS
CHANGES IN CHARACTERISTICS OF SARCOPRASMIC RETICULUM AFTER INJECTION OF BUPIVACAINE INTO RAT TIBIALIS ANTERIOR
The alteration of characteristics in the sarcoplasmic reticulum (SR) of the rat tibialis anterior muscle (TA) was examined after injection of bupivacaine (BPVC) induced muscle damage.
Male Wistar rats (7wk) were randomly divided into two groups: control (n = 9) and BPVC infection (n = 9) groups. BPVC (0.5 ml of 0.5%) was injected into the right TA for BPVC group, then the TA dissected 24 h after injection. Histochemical and biochemical analyses were performed on the TA muscles. Transverse cryostat sections were stained with haematoxylin and eosin. SR Ca2+-ATPase activity in the presence and absence of the Ca2+ ionophore A23187 was measured according to the methods described by Simonides and van Hardeveld (1990).
Twenty-four hours after BPVC injection, there was notable damage observed in the muscle, and the interstitium was infiltrated with mononuclear cells. BPVC injection evoked a 62% decrease in SR Ca2+-ATPase activity, and decreases in the ratio of the presence to absence of ionophore were observed in the BPVC muscle.
These results suggest that BPVC injection caused the dysfunction of the Ca2+-ATPase protein and loss of SR vesicle membrane integrity. These alteration in SR function may contribute to the elevation of intracellular [Ca2+], which accounts for muscle fiber injury occuring after BPVC infection. Supported by Grant-in-Aid for JSPS Research Fellows 13780006©2002The American College of Sports Medicine