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Upregulation of cardiomyocyte ribonucleotide reductase increases intracellular 2 deoxy-ATP, contractility, and relaxation

Korte, F.S., Dai, Jin, Buckley, Kate, Feest, Erik R., Adamek, Nancy, Geeves, Michael A., Murry, Charles E., Regnier, Michael (2011) Upregulation of cardiomyocyte ribonucleotide reductase increases intracellular 2 deoxy-ATP, contractility, and relaxation. Journal of Molecular and Cellular Cardiology, 51 (6). pp. 894-901. ISSN 0022-2828. (doi:10.1016/j.yjmcc.2011.08.026) (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided) (KAR id:29217)

The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided. (Contact us about this Publication)
Official URL
http://dx.doi.org/10.1016/j.yjmcc.2011.08.026

Abstract

We have previously demonstrated that substitution of ATP with 2 deoxy-ATP (dATP) increased the magnitude and rate of force production at all levels of Ca2+-mediated activation in demembranated cardiac muscle. In the current study we hypothesized that cellular [dATP] could be increased by viral-mediated overexpression of the ribonucleotide reductase (Rrm1 and Rrm2) complex, which would increase contractility of adult rat cardiomyocytes. Cell length and ratiometric (Fura2) Ca2+ fluorescence were monitored by video microscopy. At 0.5 Hz stimulation, the extent of shortening was increased ~ 40% and maximal rate of shortening was increased ~ 80% in cardiomyocytes overexpressing Rrm1 + Rrm2 as compared to non-transduced cardiomyocytes. The maximal rate of relaxation was also increased ~ 150% with Rrm1 + Rrm2 overexpression, resulting in decreased time to 50% relaxation over non-transduced cardiomyocytes. These differences were even more dramatic when compared to cardiomyocytes expressing GFP-only. Interestingly, Rrm1 + Rrm2 overexpression had no effect on minimal or maximal intracellular [Ca2+], indicating increased contractility is primarily due to increased myofilament activity without altering Ca2+ release from the sarcoplasmic reticulum. Additionally, functional potentiation was maintained with Rrm1 + Rrm2 overexpression as stimulation frequency was increased (1 Hz and 2 Hz). HPLC analysis indicated cellular [dATP] was increased by approximately 10-fold following transduction, becoming ~ 1.5% of the adenine nucleotide pool. Furthermore, 2% dATP was sufficient to significantly increase crossbridge binding and contractile force during sub-maximal Ca2+ activation in demembranated cardiac muscle. These experiments demonstrate the feasibility of directly targeting the actin–myosin chemomechanical crossbridge cycle to enhance cardiac contractility and relaxation without affecting minimal or maximal Ca2+. This article is part of a Special issue entitled "Possible Editorial".

Item Type: Article
DOI/Identification number: 10.1016/j.yjmcc.2011.08.026
Uncontrolled keywords: ? dATP enhances myocardial contraction via increased crossbridge binding and kinetics. ? [dATP] can be increased > 10-fold via ribonucleotide reductase (Rrm) overxpression. ? Rrm overexpression increased intact cardiomyocyte contractility and relaxation. ? Rrm overexpression had no effect on Ca2+ transient magnitude. ? Myofilament targeted gene manipulations can improve cardiac function.
Subjects: Q Science
Divisions: Faculties > Sciences > School of Biosciences
Depositing User: Susan Davies
Date Deposited: 27 Mar 2012 15:47 UTC
Last Modified: 23 Jan 2020 04:05 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/29217 (The current URI for this page, for reference purposes)
Geeves, Michael A.: https://orcid.org/0000-0002-9364-8898
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