Ra. Fielding et al., ACUTE-PHASE RESPONSE IN EXERCISE .3. NEUTROPHIL AND IL-1-BETA ACCUMULATION IN SKELETAL-MUSCLE, The American journal of physiology, 265(1), 1993, pp. 180000166-180000172
Nine untrained men (22-29 yr) performed 45 min of downhill running (16
% incline, 70% of maximum heart rate). Needle biopsies of the vastus l
ateralis were performed before, 45 min after, and 5 days after exercis
e. Immunohistochemical staining of muscle cross sections revealed a 13
5% increase in muscle interleukin-1beta (IL-1beta) immediately after a
nd a 250% increase (P < 0.03) 5 days after exercise. Using a rating sc
ale (0-3) for the presence of neutrophils, light microscopic examinati
on showed a significant accumulation of neutrophils in muscle biopsies
taken 45 min after and 5 days after exercise [before: 0.5 +/- 0.2, 45
min after: 1.5 +/- 0.3 (P < 0.01), and 5 days after: 1.2 +/- 0.2 (P <
0.04)]. In addition, electron microscopic analysis showed an increase
in the percentage of damaged Z-bands relative to total Z-bands [befor
e: 4.8 +/- 3.5%, 45 min after: 32.5 +/- 8.6% (P < 0.05), and 5 days af
ter: 14.1 +/- 3.2%]. Neutrophil accumulation was positively correlated
to intracellular Z-band damage (rho = 0.66, P < 0.001). Immunohistoch
emical staining for IL-1beta was related to neutrophil accumulation in
muscle (rho = 0.38, P < 0.06) and to plasma creatine kinase levels (r
ho = 0.416, P < 0.04). These data indicate that after eccentric exerci
se ultrastructural damage to skeletal muscle is associated with neutro
phil infiltration and muscle IL-1beta accumulation.