title: Myosin isoforms in neonatal rat extensor digitorum longus, diaphragm, and soleus muscles.
abstract: The postnatal elimination of embryonic and neonatal myosin isoforms in the rat extensor digitorum longus, diaphragm, and soleus muscles was compared using electrophoresis and immunohistochemical techniques. Electrophoresis of native myosin showed that neonatal bands were present in all three muscles on day 4 but were absent from the day 21 extensor digitorum longus muscle that exhibited its adult electrophoretic pattern. Mature electrophoretic banding patterns were present on days 60 and 125 in the diaphragm and soleus muscles, respectively. Immunohistochemical analysis indicated that embryonic myosin heavy chain was present in all day 4 samples but absent by day 21. Quantitative evaluation determined that the rate of elimination of neonatal myosin heavy chain (MHCneo) was faster in the extensor digitorum longus muscle than in the diaphragm, with the soleus muscle having the slowest rate of elimination of this isoform. Embryonic myosin light chain was detected by two-dimensional electrophoresis through day 8 in each of the muscles. These data indicate that postnatal elimination of MHCneo is tissue specific and time dependent but not governed by either activity level or rostral-caudal position.
authors.affiliation: Department of Neurobiology, University of Pittsburgh, School of Medicine, Pennsylvania 15261.
authors.forename: W A
authors.initials: WA
authors.lastname: LaFramboise
authors.forename: M J
authors.initials: MJ
authors.lastname: Daood
authors.forename: R D
authors.initials: RD
authors.lastname: Guthrie
authors.forename: G S
authors.initials: GS
authors.lastname: Butler-Browne
authors.forename: R G
authors.initials: RG
authors.lastname: Whalen
authors.forename: M
authors.initials: M
authors.lastname: Ontell
mesh_terms: D000375:Aging; D000818:Animals; D000831:Animals, Newborn; D003964:Diaphragm; D015180:Electrophoresis, Gel, Two-Dimensional; D004591:Electrophoresis, Polyacrylamide Gel; D005333:Fetus; D007150:Immunohistochemistry; D024510:Muscle Development; D009132:Muscles / Q000166:cytology / Q000196:embryology; D015879:Myosin Subfragments / Q000032:analysis*; D009928:Organ Specificity; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D015879:Myosin Subfragments