Regulation of muscle cell proliferation by extracts from crushed muscle.
Cell culture studies were conducted to determine whether myotrophic factors were released from mature murine or bovine muscle following a crush injury. Murine crushed muscle extract (mCME) was added to C2 muscle (satellite) cell cultures at concentrations of 0, 50, 100, 200, and 400 micrograms of total protein/mL. Bovine crushed muscle extract (bCME) was added at concentrations of 0, 100, 200, 400, and 500 micrograms/mL. Murine CME and bCME at each concentration caused an increase (P < .01) in [3H]TdR incorporation into muscle cells compared to control cultures. The saturating concentrations (P < .01) of CME in the presence of 2% FBS were approximately 200 and 400 micrograms/mL for murine and bovine extracts, respectively. Murine CME or bCME acted in an additive fashion with independent, saturating concentrations of the insulin-like growth factors (IGF-I and IGF-II), basic fibroblast growth factor (bFGF), and transforming growth factor-beta (TGF-beta) to increase (P < .01) C2 muscle cell proliferation. Subsequently, in separate experiments, mCME or bCME acted additively with a combination of all growth factors to increase (P < .01) cell proliferation. Combining mCME and bCME at saturating levels in one treatment was not (P > .05) additive to that elicited by either CME alone. These results suggest that myotrophic factors are released following injury in mature skeletal muscle, and they are not species-specific.
Haugk
K L
KL
Department of Animal and Veterinary Science, University of Idaho, Moscow 83844, USA.
Roeder
R A
RA
Garber
M J
MJ
Schelling
G T
GT
D000818:Animals; D002417:Cattle; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D017077:Culture Media, Conditioned / Q000032:analysis / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D007335:Insulin-Like Growth Factor II / Q000494:pharmacology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D018482:Muscle, Skeletal / Q000737:chemistry / Q000166:cytology* / Q000378:metabolism; D013936:Thymidine / Q000378:metabolism; D014020:Tissue Extracts / Q000494:pharmacology*; D016212:Transforming Growth Factor beta / Q000494:pharmacology; D014316:Tritium
D017077:Culture Media, Conditioned; D014020:Tissue Extracts; D016212:Transforming Growth Factor beta; D014316:Tritium; D016222:Fibroblast Growth Factor 2; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D013936:Thymidine