Hemin enhances differentiation and maturation of cultured regenerated skeletal myotubes.
Satellite cells, isolated from marcaine-damaged rat skeletal muscle, differentiate in culture to form contracting, cross-striated myotubes. Addition of 20 microM hemin (ferriprotoporphyrin IX chloride) to the culture medium resulted in increases in the number, size, and alignment of myotubes; in the number of myotubes that exhibited cross-striations; and in the strength and frequency of myotube contractions. Hemin increased satellite cell fusion by 27%, but decreased cell proliferative rate by 30%. Hemin increased the specific activity of creatine kinase (CK), a sensitive indicator of muscle differentiation, by 157%. Separation of CK isoenzymes by agarose gel electrophoresis showed that hemin increased only the muscle-specific CK isoenzymes (MM-CK and MB-CK). Thus, hemin seems to duplicate some of the effects of innervation on cultured myotubes by increasing contraction frequency and strength, appearance of cross-striations, and muscle-specific isoenzymes. In contrast, 3-amino-1,2,4-triazole, an inhibitor of heme biosynthesis, decreased the number of cross-striated myotubes, the strength and frequency of myotube contractions, and CK activity. These inhibitory effects were reversed by hemin. Collectively, these results demonstrate a physiologically significant role for heme in myotube maturation.
Funanage
V L
VL
Research Department, Alfred I. duPont Institute, Wilmington, Delaware 19899.
Schroedl
N A
NA
Moses
P A
PA
Smith
S M
SM
Kirwin
J J
JJ
Hartzell
C R
CR
D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D002459:Cell Fusion / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D003402:Creatine Kinase / Q000378:metabolism / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D006418:Heme / Q000031:analogs & derivatives*; D006427:Hemin / Q000494:pharmacology* / Q000502:physiology; D007501:Iron / Q000494:pharmacology; D007527:Isoenzymes; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009132:Muscles / Q000166:cytology* / Q000378:metabolism / Q000502:physiology; D051381:Rats; D012038:Regeneration / Q000187:drug effects / Q000502:physiology*; D014168:Transferrin / Q000494:pharmacology
D007527:Isoenzymes; D014168:Transferrin; D006418:Heme; D006427:Hemin; D007501:Iron; D003402:Creatine Kinase