title: Induction of hypertrophic responsiveness to isoproterenol by TGF-beta in adult rat cardiomyocytes.
abstract: In a previous publication we reported that hypertrophic responsiveness to beta-adrenoceptor stimulation can be induced in isolated cardiomyocytes when these are cultured for 6 days in presence of fetal calf serum (FCS; Pinson et al., J. Mol. Cell. Cardiol.. 25: 477-490, 1993). The role of transforming growth factor-beta (TGF-beta) in this induction process has now been investigated. Isolated cardiomyocytes from adult rats were cultured for 6 days in presence of 20% FCS. It was found that induction of hypertrophic responsiveness to beta-adrenoceptor stimulation was abolished when a neutralizing anti-TGF-beta 1 antibody was added to FCS-containing culture medium. In culture media with FCS contents (5%) too low to induce hypertrophic responsiveness to beta-adrenoceptor stimulation, addition of 1 ng/ml TGF-beta 1,2 induces this responsiveness. It was demonstrated that cardiomyocytes already release TGF-beta into culture media on day 1 of culture and that they continue to do so in presence of FCS supplements of > 5%. The results demonstrate that hypertrophic responsiveness to beta-adrenoceptor stimulation is induced in cardiomyocytes by an autocrine mechanism involving TGF-beta 1 as mediator.
mesh_terms: D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000818:Animals; D006332:Cardiomegaly / Q000139:chemically induced* / Q000473:pathology*; D002417:Cattle; D002478:Cells, Cultured; D003470:Culture Media; D007545:Isoproterenol / Q000494:pharmacology*; D008297:Male; D009206:Myocardium / Q000473:pathology*; D051381:Rats; D013997:Time Factors; D016212:Transforming Growth Factor beta / Q000502:physiology*
chemical_list: D000318:Adrenergic beta-Agonists; D003470:Culture Media; D016212:Transforming Growth Factor beta; D007545:Isoproterenol