Mitochondrial Dysfunction Contributes to Decompensation in a Zebrafish Model of Isoproterenol-Induced Heart Failure

Area of Science:

• Cardiovascular Biology
• Mitochondrial Physiology
• Zebrafish Models

Background:

• Heart failure is characterized by impaired cardiac function due to structural or functional heart defects.
• Mitochondrial dysfunction is a key factor contributing to contractile impairment in heart failure.
• Understanding the progression of heart failure is crucial for developing effective treatments.

Purpose of the Study:

• To investigate the relationship between calcium dynamics, cardiac mechanical performance, and mitochondrial ATP production during heart failure progression.
• To utilize a zebrafish model to study the effects of chronic isoproterenol stimulation on cardiac function and mitochondrial health.
• To identify molecular changes associated with heart failure development and decompensation.

Main Methods:

• Induction of heart failure in zebrafish larvae using chronic isoproterenol exposure (100 μM from 3 to 14 days postfertilization).
• In vivo assessment of cardiac calcium transients, contractility, and mitochondrial ATP levels using fluorescent biosensors in transgenic zebrafish.
• Transcriptomic analysis (RNA sequencing) of hearts at 14 days postfertilization to identify gene expression changes.

Main Results:

• Early isoproterenol treatment (7 dpf) caused ventricular dilation, reduced calcium levels, and decreased contractility, but maintained cardiac output.
• Extended treatment (14 dpf) led to decompensated heart failure with significantly reduced cardiac output and a marked drop in mitochondrial ATP levels.
• Transcriptomic analysis revealed downregulation of mitochondrial energy metabolism and transfer pathways at the decompensated stage.

Conclusions:

• Zebrafish larvae exposed to isoproterenol exhibit progressive heart dysfunction mirroring human heart failure.
• Cardiac decompensation is closely linked to a collapse in mitochondrial ATP production.
• The study underscores the critical role of mitochondrial energy metabolism in maintaining cardiac function during heart failure.