Key result
ETB deficiency blunts sympathetic stress responses, promoting vagal dominance and frequent bradyarrhythmias.
Why the study?
While baseline plasma endothelin levels alter blood pressure responses, it remained unclear whether autonomic activity and arrhythmogenesis during acute emotional stress are affected.
Does elevated plasma endothelin (via ETB-deficiency) modulate autonomic responses and arrhythmogenesis during acute emotional stress in rats?
Does elevated plasma endothelin (via ETB-deficiency) modulate autonomic responses and arrhythmogenesis during acute emotional stress in rats?
Chronically elevated plasma endothelin levels blunt sympathetic responses to acute emotional stress in rats, leading to vagal dominance and bradyarrhythmias rather than tachyarrhythmias.
Does not inform clinical stress management; leaves open whether endothelin modulates human autonomic responses and bradyarrhythmias during emotional stress.
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 ETB-deficient rats, the latter displaying elevated plasma endothelin. No differences in heart rate or blood pressure were evident, but sympathetic responses were blunted in ETB-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 ETB-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 ETB-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.
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Mouchtouri et al. (2023) studied Acute emotional stress (n=56). ETB-deficiency (chronically elevated plasma endothelin) vs. Wild-type rats was evaluated on Autonomic responses (sympathetic and vagal indices) and rhythm disturbances to acute emotional stress. Chronically elevated plasma endothelin levels in ETB-deficient rats blunted sympathetic responses to acute emotional stress, resulting in vagal dominance and frequent bradyarrhythmias compared to wild-type rats.
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