Distribution of alpha- and beta-myosin heavy chains in the ventricular fibers of the postnatal developing rat.
Four monoclonal antibodies, two raised against alpha-myosin heavy chain (MHC) and two against beta-MHC, have been used to investigate in situ the fiber distribution of alpha- and beta-MHC in rat cardiac ventricles during postnatal development. Eighteen ventricles from 2-day-old to 1-year-old rats were analyzed. Three fiber populations were determined according to their immunofluorescent labeling: one with only alpha-MHC, one only beta-MHC, and one with mixed alpha- and beta-MHC. Large variations in the proportions of these three fiber populations according to age indicate that: (1) alpha-MHC are expressed in all fibers until the second month; they then disappear in a small endocardial fiber population and in a few apparently conductive fibers around the vessels. (2) beta-MHC are also first expressed in all fibers and then disappear gradually from epicardium to endocardium between the second and fourth weeks, except in the conductive fibers; they reappear during the second month sequentially from endocardium to epicardium; and they are then expressed in almost all fibers, except in a small epicardial fiber population, proportionally larger in the right ventricle than in the left. Immunological characterization of MHC isolated from a 22-day-old-rat ventricle, using anti-beta immunoaffinity chromatography, suggests that MHC of conductive fibers are probably at least partially in an alpha beta heterodimeric form.
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D000375:Aging; D000818:Animals; D000831:Animals, Newborn; D005455:Fluorescent Antibody Technique; D006321:Heart / Q000254:growth & development*; D006352:Heart Ventricles / Q000166:cytology / Q000254:growth & development; D008297:Male; D015879:Myosin Subfragments; D009218:Myosins / Q000032:analysis*; D010446:Peptide Fragments / Q000032:analysis*; D051381:Rats; D011919:Rats, Inbred Strains
D015879:Myosin Subfragments; D010446:Peptide Fragments; D009218:Myosins