Mechanical factors in the initiation of eccentric contraction-induced injury in rat soleus muscle.

摘要: 1. Mechanical factor(s) associated with the initiation of eccentric contraction-induced muscle injury were investigated in isolated rat soleus muscles (n = 180; 42 protocols 4-6 per protocol). Five contractions performed 4 min between contractions. Three levels peak contraction force (100, 125 and 150% pre-injury maximal isometric tetanic tension, P0), length change (0.1, 0.2 0.3 length, L0) lengthening velocity (0.5, 1.0 1.5 L0/s) utilized. Force was varied stimulation frequency (10-150 Hz). The initiated at lengths 0.85 or 0.90 L0. Following fifth contraction, incubated Krebs-Ringer buffer for 60 min. Peak twitch tension (PT), P0, rate development (+ dP/dt), relaxation (-dP/dt), creatine kinase (CK) release measured prior to five 15 intervals during incubation period. Total [Ca2+] after incubation. 2. mean (+/- S.E.M.) initial decline P0 performing most injurious protocol 13.6 +/- 4.8% 6); control immediately following performance elevated 1.2 1.0% 8). These means different probability, p 0.005. Mean [ATP] protocols, respectively, 16.30 1.49 19.84 1.38 mumol/g dry wt (p 0.229). 3. Decrements PT, +dP/dt, -dP/dt related closely forces produced contractions; greater declines +dP/dt also observed higher velocities independent force. Slow greatest longer length. CK all mechanical factors exception velocity. activity 45 into period lengthened highest used (1.5 L0/s). total by 38% over but elevation unrelated any four factors. 4. data support hypothesis that is factors, playing dominant role.(ABSTRACT TRUNCATED AT 400 WORDS)