The effects of tumor necrosis factor-alpha on systolic and diastolic function in rat ventricular myocytes
Greensmith, DJ and Nirmalan, M 2013, 'The effects of tumor necrosis factor-alpha on systolic and diastolic function in rat ventricular myocytes' , Physiological reports, 1 (4) , e00093.
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The proinflammatory cytokine tumor necrosis factor-alpha (TNF-α) is associated with myocardial dysfunction observed in sepsis and septic shock. There are two fundamental components to this dysfunction. (1) systolic dysfunction; and (2) diastolic dysfunction. The aim of these experiments was to determine if any aspect of whole-heart dysfunction could be explained by alterations to global intracellular calcium ([Ca(2+)]i), contractility, and [Ca(2+)]i handling, by TNF-α, at the level of the individual rat myocyte. We took an integrative approach to simultaneously measure [Ca(2+)]i, contractility and sarcolemmal Ca fluxes using the Ca indicator fluo-3, video edge detection, and the perforated patch technique, respectively. All experiments were performed at 37°C. The effects of 50 ng/mL TNF-α were immediate and sustained. The amplitude of systolic [Ca(2+)]i was reduced by 31% and systolic shortening by 19%. Diastolic [Ca(2+)]i, myocyte length and relaxation rate were not affected, nor were the activity of the [Ca(2+)]i removal mechanisms. The reduction in systolic [Ca(2+)]i was associated with a 14% reduction in sarcoplasmic reticulum (SR) content and a 11% decrease in peak L-type Ca current (IC a-L). Ca influx was decreased by 7% associated with a more rapid IC a-L inactivation. These data show that at the level of the myocyte, TNF-α reduces SR Ca which underlies a reduction in systolic [Ca(2+)]i and thence shortening. Although these findings correlate well with aspects of systolic myocardial dysfunction seen in sepsis, in this model, acutely, TNF-α does not appear to provide a cellular mechanism for sepsis-related diastolic myocardial dysfunction.
|Themes:||Health and Wellbeing
Subjects outside of the University Themes
|Schools:||Schools > School of Environment and Life Sciences > Biomedical Research Centre|
|Journal or Publication Title:||Physiological reports|
|Funders:||Manchester University Strategic Studentship Scheme|
|Depositing User:||D Greensmith|
|Date Deposited:||10 Feb 2015 20:42|
|Last Modified:||10 Feb 2015 20:42|
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