Modulation of Myocardial Stiffness by ß-Adrenergic Stimulation - Its Role in Normal and Failing Heart

• Type: Article in International Scientific Journal
• Date: 2011

Authors

Falcao Pires, I (Author) FMUP; FONTES-SOUSA, AP (Author) Other; LOPES-CONCEIÇÃO, L (Author) Other; BRÁS-SILVA, C (Author) Other; LEITE-MOREIRA, AF (Author) Other

Journal

Title: Physiological Research

Pages: 599-609

ISSN: 0862-8408

Publisher: Akademie Ved Ceske Republiky

Other information

Authenticus ID: P-00S-GFX

DOI: 10.33549/physiolres.932088

Abstract (EN): <jats:p>The acute effects of ß-adrenergic stimulation on myocardial stiffness were evaluated. New-Zealand white rabbits were treated with saline (control group) or doxorubicin to induce heart failure (HF) (DOXO-HF group). Effects of isoprenaline (10-10-10-5 M), a non-selective ß-adrenergic agonist, were tested in papillary muscles from both groups. In the control group, the effects of isoprenaline were also evaluated in the presence of a damaged endocardial endothelium, atenolol (ß1-adrenoceptor antagonist), ICI-118551 (ß2-adrenoceptor antagonist), KT-5720 (PKA inhibitor), L-NNA (NO-synthase inhibitor), or indomethacin (cyclooxygenase inhibitor). Passive length-tension relations were constructed before and after adding isoprenaline (10-5 M). In the control group, isoprenaline increased resting muscle length up to 1.017±0.006 L/Lmax. Correction of resting muscle length to its initial value resulted in a 28.5±3.1 % decrease of resting tension, indicating decreased muscle stiffness, as confirmed by the isoprenaline-induced right-downward shift of the passive length-tension relation. These effects were modulated by ß1- and ß2-adrenoceptors and PKA. In DOXO-HF group, the effect on myocardial stiffness was significantly decreased. We conclude that ß-adrenergic stimulation is a relevant mechanism of acute neurohumoral modulation of the diastolic function. Furthermore, this study clarifies the mechanisms by which myocardial stiffness is decreased.</jats:p>

Language: English

Type (Professor's evaluation): Scientific