Alpha-skeletal actin is associated with increased contractility in the mouse heart.
BALB/c mice express abnormally high levels of alpha-skeletal actin in the heart, which may be related to a duplication in the promoter of the alpha-cardiac actin gene. To evaluate the effects of overexpression of the alpha-skeletal actin isoform on cardiac contractile function, we studied these mice using the isolated perfused work-performing murine heart model and measured actin isoform expression in the same hearts. We quantified myocardial contractility from the maximum rate of contraction (+dP/dt) and time to peak pressure and relaxation from -dP/dt and time to half relaxation of left intraventricular pressure. Dot blots of total RNA hybridized against oligonucleotide sequences specific for either alpha-skeletal or alpha-cardiac actin mRNA showed that increased levels of alpha-skeletal actin RNA correlated significantly with increased contractility of hearts from the BALB/c mice (r = .80, n = 15, P < .001). The present study demonstrates a significant functional correlation between alpha-actin isoform content and cardiac contractile function and also that alpha-skeletal actin may promote an increased contractile function in the heart compared with alpha-cardiac actin.
Hewett
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Cincinnati Sportsmedicine Research and Education Foundation, University of Cincinnati, College of Medicine, Ohio.
Grupp
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IL
Grupp
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Robbins
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J
D000199:Actins / Q000235:genetics / Q000502:physiology*; D000818:Animals; D006332:Cardiomegaly / Q000378:metabolism; D005260:Female; D015870:Gene Expression; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D009200:Myocardial Contraction; D009206:Myocardium / Q000378:metabolism; D009218:Myosins / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis
D000199:Actins; D012333:RNA, Messenger; D009218:Myosins