Influence of mechanical activity, adrenergic stimulation, and calcium on the expression of myosin heavy chains in cultivated neonatal cardiomyocytes
✍ Scribed by Hans Peter Luther; Simone Hille; Hannelore Haase; Ingo Morano
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 106 KB
- Volume
- 64
- Category
- Article
- ISSN
- 0730-2312
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✦ Synopsis
It is generally accepted that mechanical stress of cardiomyocytes increases RNA and protein synthesis of myosin heavy chain (MHC) quantitatively but it is still a matter of debate whether MHC gene expression is also changed qualitatively. We investigated expression of MHC genes of spontaneously contracting neonatal cardiomyocytes experimentally arrested by permanent depolarization [potassium chloride (KCl)] as well as by electromechanical uncoupling [2,3 butanedione monoxime (BDM)]. Relative distribution of MHC mRNA isoforms (a and b) was studied by quantitative polymerase chain reaction. Expression of MHC isoenzymes was the same in contracting (34.5% b-MHC) and arrested (40.5% and 33.0% b-MHC in KCl and BDM, respectively) cardiomyocytes. However, treatment with phenylephrine for the same period increased significantly b-MHC expression to 55%. We conclude that hormonal factors rather than Ca 21 or mechanical stress regulate qualitatively MHC gene expression.