Enhanced procollagen processing in skeletal muscle after a single bout of eccentric loading in humans.
Increases in procollagen processing within skeletal muscle have previously been reported in small animal models only. While indirect measurements in humans have suggested an increase procollagen processing, no intra-skeletal muscle measurements have confirmed these findings. In this study, eight young healthy male subjects performed a single bout of unaccustomed high intensity eccentric exercise on one leg, with the contralateral leg being the control. A significant increase in the muscle interstitial concentration of the N-terminal propeptide of procollagen type I (PINP) was observed (day 0: 1.96 +/- 0.44 ng ml(-1), day 2: 1.94 +/- 0.32 ng ml(-1), day 4: 3.90 +/- 1.03 ng ml(-1), day 8: 7.23 +/- 2.34 ng ml(-1)*, *P < 0.05 vs. basal and control) with no change being noted in the control leg. By day 2 post-exercise, an increase in the histological immunoreactivity of PINP and the N-terminal propeptide of procollagen type III (PIIINP) was also shown in the exercising leg only. Further, from day 2 post-exercise, immunoreactivity for tenascin C and reactive macrophages (CD68+ cells) was seen within the perimysial and endomysial connective tissue of the exercising leg only, indicating a high mechanical load and inflammation. This study shows that following a single bout of high intensity eccentric exercise there is an increase in procollagen processing within skeletal muscle in humans.
Crameri
Regina M
RM
Sports Medicine Research Unit, Bispebjerg Hospital, DK-2400, Copenhagen NV, Denmark. rcrameri@alcor.concordia.ca
Langberg
Henning
H
Teisner
Børge
B
Magnusson
Peter
P
Schrøder
Henrik Daa
HD
Olesen
Jens L
JL
Jensen
Charlotte H
CH
Koskinen
Satu
S
Suetta
Charlotte
C
Kjaer
Michael
M
D000328:Adult; D015444:Exercise / Q000502:physiology*; D016326:Extracellular Matrix Proteins / Q000378:metabolism; D006801:Humans; D007866:Leg; D008264:Macrophages / Q000166:cytology; D008297:Male; D009000:Monocytes / Q000166:cytology; D018482:Muscle, Skeletal / Q000166:cytology / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism; D011347:Procollagen / Q000378:metabolism*; D019063:Tenascin / Q000378:metabolism
D016326:Extracellular Matrix Proteins; D010446:Peptide Fragments; D011347:Procollagen; D019063:Tenascin; C047202:procollagen Type I N-terminal peptide; C041876:procollagen Type III-N-terminal peptide