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Updated: Dec 9, 2025
A Doxorubicin-induced Cardiomyopathy Model in Adult Zebrafish
Published on: June 7, 2018
Doxorubicin Cytotoxicity in Differentiated H9c2 Cardiomyocytes: Evidence for Acute Mitochondrial Superoxide
Muath Helal1, Jane Alcorn1, Brian Bandy2
1College of Pharmacy and Nutrition, University of Saskatchewan, Saskatoon, SK, S7N 5E5, Canada.
Abstract:
Although a mitochondrial redox-cycling superoxide-generating mechanism for the cardiotoxicity of doxorubicin was suggested from experiments with isolated mitochondria, its occurrence and contribution to cytotoxicity in intact cardiomyocytes is not fully established. Therefore, we determined the immediate and delayed effects of doxorubicin on the generation of reactive oxygen species (ROS) and cytotoxicity in differentiated H9c2 cardiomyocytes. Although relatively short incubations (3 or 6 h) with 1 or 5 µM doxorubicin did not acutely decrease cell survival, exposure to 5 µM doxorubicin for 3 h was sufficient to cause a significant delayed decrease in cell survival after an additional 24 h without doxorubicin. Mitochondrial superoxide generation was observed to increase within 30 min of incubation with 5 µM doxorubicin. Increased intracellular ROS generation, decreased mitochondrial metabolic activity, and decreased mitochondrial membrane potential (MMP) were observed after more extended periods (6-12 h). Overall, these observations support that the toxicity of doxorubicin to differentiated cardiomyocytes involves acute mitochondrial superoxide generation with subsequent intracellular ROS generation, mitochondrial dysfunction, and cell death.
Insights
Doxorubicin causes delayed cardiotoxicity in cardiomyocytes by increasing mitochondrial superoxide generation and reactive oxygen species (ROS), leading to cell death. This study confirms the mechanism in intact heart cells.
Area of Science:
- Biochemistry
- Cardiology
- Toxicology
Background:
- Mitochondrial mechanisms of doxorubicin cardiotoxicity are not fully understood in intact cardiomyocytes.
- Previous studies suggested mitochondrial superoxide generation, but in vitro evidence was limited.
Purpose of the Study:
- To investigate the immediate and delayed effects of doxorubicin on reactive oxygen species (ROS) generation and cytotoxicity in differentiated H9c2 cardiomyocytes.
- To elucidate the role of mitochondrial superoxide generation in doxorubicin-induced cardiotoxicity.
Main Methods:
- Differentiated H9c2 cardiomyocytes were exposed to varying concentrations of doxorubicin.
- Measurements included cell survival, mitochondrial superoxide generation, intracellular ROS levels, mitochondrial metabolic activity, and mitochondrial membrane potential (MMP).
Main Results:
- Doxorubicin exposure (5 µM, 3h) induced significant delayed cytotoxicity.
- Mitochondrial superoxide generation increased rapidly (within 30 min).
- Increased intracellular ROS, decreased mitochondrial activity, and reduced MMP were observed at later time points (6-12h).
Conclusions:
- Doxorubicin cardiotoxicity in cardiomyocytes involves acute mitochondrial superoxide generation.
- Subsequent intracellular ROS production and mitochondrial dysfunction contribute to cell death.
- This study validates the mitochondrial ROS mechanism in intact cardiac cells.
