Stimulation and inhibition of cardiac myocyte proliferation in vitro.
We have examined the effect of crude cardiac tissue extracts as well as that of several growth factors and triiodothyronin (T3) on DNA synthesis of cardiac myocytes in culture. Extracts from embryonic and adult cardiac tissue stimulated DNA synthesis of myocytes. Atrial myocytes exhibited overall higher degree of stimulation than their ventricular counterparts and extracts from adult atrial tissue had the highest apparent mitogenic activity for atrial myocytes. We have shown that adult heart contains basic fibroblast growth factor (bFGF), especially in the atria. Transforming growth factor beta (TGF beta) and insulin-like growth factors (IGFs) are also accumulated in cardiac tissues. We found that bFGF and the IGFs stimulate myocyte cell proliferation and DNA synthesis. These factors also stimulate cardiac non-muscle proliferation, especially in the presence of serum. TGF beta inhibited proliferation and DNA synthesis and cancelled the effect of bFGF or IGFs on the myocytes. T3 also diminished the bFGF-induced mitogenic stimulation of cardiomyocytes. Our data suggest that these factors may be involved in the regulation of cardiomyocyte proliferation in vivo.
Kardami
E
E
St. Boniface General Hospital Research Centre, Division of Cardiovascular Sciences, University of Manitoba, Winnipeg, Canada.
D000818:Animals; D002417:Cattle; D002452:Cell Count; D002455:Cell Division / Q000187:drug effects / Q000235:genetics; D002645:Chickens; D004247:DNA / Q000096:biosynthesis / Q000187:drug effects; D006133:Growth Substances / Q000494:pharmacology*; D006321:Heart / Q000187:drug effects / Q000254:growth & development; D009206:Myocardium / Q000166:cytology*; D051381:Rats; D011919:Rats, Inbred Strains; D014284:Triiodothyronine / Q000494:pharmacology
D006133:Growth Substances; D014284:Triiodothyronine; D004247:DNA