| Autor: |
Mouchtouri ET; Department of Cardiology, Medical School, University of Ioannina, 45500 Ioannina, Greece.; Cardiovascular Research Institute, 45500 Ioannina, Greece., Konstantinou T; Department of Cardiology, Medical School, University of Ioannina, 45500 Ioannina, Greece.; Cardiovascular Research Institute, 45500 Ioannina, Greece., Lekkas P; Cardiovascular Research Institute, 45500 Ioannina, Greece., Lianopoulou A; School of Applied Biology and Biotechnology, Agricultural University of Athens, 10447 Athens, Greece., Kotsaridou Z; School of Applied Biology and Biotechnology, Agricultural University of Athens, 10447 Athens, Greece., Mourouzis I; Department of Pharmacology, National and Kapodistrian University of Athens, 11527 Athens, Greece., Pantos C; Department of Pharmacology, National and Kapodistrian University of Athens, 11527 Athens, Greece., Kolettis TM; Department of Cardiology, Medical School, University of Ioannina, 45500 Ioannina, Greece.; Cardiovascular Research Institute, 45500 Ioannina, Greece. |
| Abstrakt: |
The ubiquitous peptide endothelin is currently under investigation as a modulatory factor of autonomic responses to acute emotional stress. Baseline plasma levels of endothelin alter blood pressure responses, but it remains unclear whether autonomic activity and arrhythmogenesis (i.e., brady- or tachyarrhythmias) are affected. We recorded sympathetic and vagal indices (derived from heart rate variability analysis), rhythm disturbances, voluntary motion, and systolic blood pressure after acute emotional stress in conscious rats with implanted telemetry devices. Two strains were compared, namely wild-type and ET B -deficient rats, the latter displaying elevated plasma endothelin. No differences in heart rate or blood pressure were evident, but sympathetic responses were blunted in ET B -deficient rats, contrasting prompt activation in wild-type rats. Vagal withdrawal was observed in both strains at the onset of stress, but vagal activity was subsequently restored in ET B -deficient rats, accompanied by low voluntary motion during recovery. Reflecting such distinct autonomic patterns, frequent premature ventricular contractions were recorded in wild-type rats, as opposed to sinus pauses in ET B -deficient rats. Thus, chronically elevated plasma endothelin levels blunt autonomic responses to acute emotional stress, resulting in vagal dominance and bradyarrhythmias. Our study provides further insights into the pathophysiology of stress-induced tachyarrhythmias and syncope. |
