These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Phosphorylation of C-protein, troponin I and phospholamban in isolated rabbit hearts.
    Author: Garvey JL, Kranias EG, Solaro RJ.
    Journal: Biochem J; 1988 Feb 01; 249(3):709-14. PubMed ID: 2895634.
    Abstract:
    Phosphorylation of myofibrillar and sacroplasmic-reticulum (SR) proteins was studied in Langendorff-perfused rabbit hearts subjected to various inotropic interventions. Stimulation of hearts with isoprenaline resulted in the phosphorylation of both troponin I (TnI) and C-protein in myofibrils and phospholamban in SR. Phosphorylation of phospholamban could be reversed by a 15 min perfusion with drug-free buffer, after a 1 minute pulse perfusion with isoprenaline, at which time the mechanical effects of isoprenaline stimulation had also been reversed. However, both TnI and C-protein remained phosphorylated at this time. Moreover, the inhibition of Ca2+ activation of the Mg2+-dependent ATPase (Mg-ATPase) activity associated with myofibrillar phosphorylation persisted in myofibrils prepared from hearts frozen after 15 min of washout of isoprenaline. To assess the contribution of C-protein phosphorylation in the decrease of Ca2+ activation of the myofibrillar Mg-ATPase activity, we reconstituted a regulated actomyosin system in which only C-protein was phosphorylated. In this system, C-protein phosphorylation did not contribute to the decrease in Ca2+ activation of Mg-ATPase activity, indicating that TnI phosphorylation is responsible for the diminished sensitivity of the myofibrils to Ca2+. These observations support the hypothesis that phospholamban phosphorylation plays a more dominant role than TnI or C-protein phosphorylation in the mechanical response of the mammalian heart to beta-adrenergic stimulation.
    [Abstract] [Full Text] [Related] [New Search]