# In vivo visualization of cardiac extracellular adenosine dynamics and its pharmacological modulation in zebrafish heart failure models

## TL;DR

This study uses a zebrafish model to visualize and modulate extracellular adenosine dynamics in heart failure, identifying a new therapeutic target.

## Contribution

The study provides in vivo evidence linking extracellular ATP/Ado signaling to heart failure and introduces VNUT as a novel therapeutic target.

## Key findings

- Zebrafish with heart failure showed increased extracellular cardiac adenosine, indicating elevated ATP release.
- Pharmacological inhibition of VNUT reduced extracellular ATP/Ado levels and improved cardiac dysfunction.
- Combining VNUT inhibitors with purinergic modulators had additive therapeutic effects in heart failure models.

## Abstract

Heart failure (HF) remains a major clinical challenge with poor prognosis despite extensive research and established treatments. Extracellular ATP and adenosine (Ado), as damage-associated molecular patterns (DAMPs), contribute to HF pathogenesis through pro-inflammatory effects. However, in vivo evidence of ATP/Ado dynamics in failing hearts remains elusive. In this study, we investigated the spatiotemporal dynamics of extracellular Ado in a zebrafish HF model using a genetically encoded heart-specific extracellular Ado sensor (GRABAdo). Terfenadine-induced HF zebrafish showed increased extracellular cardiac Ado, indirectly reflecting elevated extracellular ATP release. These findings demonstrate a strong correlation between extracellular ATP/Ado dynamics and HF progression. Furthermore, pharmacological inhibition of vesicular nucleotide transporter (VNUT), a key regulator of ATP vesicle exocytosis, reduced extracellular ATP/Ado levels and ameliorated cardiac dysfunction in the HF model. Co-treatment with a VNUT inhibitor and purinergic modulators showed additive therapeutic effects. Thus, this study aimed to provide in vivo evidence linking extracellular ATP/Ado signaling to HF pathophysiology and highlight VNUT as a novel therapeutic target for HF. Given the multifactorial nature of HF and the limited success of current anti-inflammatory strategies, targeting purinergic signaling through VNUT inhibition offers a promising approach for managing inflammatory mechanisms in HF.