Zebrafish heart as a model to study the integrative autonomic control of pacemaker function

Area of Science:

• Cardiovascular Physiology
• Neuroscience
• Comparative Biology

Background:

• Understanding neural control of heart rate is crucial for cardiac chronotropy.
• Mammalian models present challenges for integrative neurocardiac studies due to embedded neurons.
• Identifying neuronal populations controlling pacemaker cells remains a fundamental challenge.

Purpose of the Study:

• To establish the isolated, innervated zebrafish heart as a novel model for studying autonomic control of heart rate.
• To investigate the effects of vagosympathetic nerve stimulation on cardiac function in zebrafish.
• To characterize the role of sinoatrial and atrioventricular pacemakers in zebrafish cardiac control.

Main Methods:

• Isolated, innervated zebrafish heart preparation.
• Vagosympathetic nerve trunk stimulation and pharmacological agent application.
• Optical mapping of cardiac electrical activity.

Main Results:

• Vagosympathetic nerve stimulation evoked dose-dependent bradycardia and tachycardia.
• Cholinergic and adrenergic agents mimicked the effects of nerve stimulation.
• Optical mapping identified sinoatrial and atrioventricular pacemakers, with nerve stimulation shifting excitation origin.
• Pacemaker cells expressed adrenergic β2 and cholinergic muscarinic type 2 receptors.

Conclusions:

• The zebrafish heart preparation exhibits key features of vertebrate cardiac control.
• This model is suitable for integrative studies of autonomic control of heart rate.
• Zebrafish provide a valuable platform for investigating neurocardiac physiology.