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Published on: April 21, 2014
Sex difference in the repolarization currents of rabbit ventricular cells
Yanfei Ruan1, Nian Liu, Qiang Zhou
1Department of Cardiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
Summary
Female rabbits exhibit longer QT intervals and increased drug-associated torsade de pointes risk due to lower IK,tail currents in ventricular myocytes, impacting cardiac repolarization.
Area of Science:
- Cardiology
- Electrophysiology
- Molecular and Cellular Biology
Background:
- Female rabbits show a higher incidence of drug-induced torsade de pointes and longer QT intervals compared to males.
- Understanding the underlying electrophysiological differences is crucial for cardiac safety assessments.
Purpose of the Study:
- To investigate sex-based differences in rabbit ventricular myocytes.
- To elucidate the ionic mechanisms contributing to longer QT intervals and torsade de pointes susceptibility in female rabbits.
Main Methods:
- Whole-cell patch-clamp technique applied to left ventricular myocytes from male and female rabbits.
- Recorded action potential duration (APD) and ionic currents including Ito, IK,tail, IK1, and ICa,L.
- Compared membrane capacitance, APD90, and individual ionic current densities between sexes.
Main Results:
- Action potential duration at 90% repolarization (APD90) was significantly longer in female rabbits (560.4 ms) than in male rabbits (489.0 ms).
- A significant reduction in IK,tail current density was observed in female rabbit myocytes (0.71 pA/pF) compared to males (0.84 pA/pF).
- No significant differences were found in Ito, IK1, or ICa,L current densities between male and female rabbit myocytes.
Conclusions:
- Lower IK,tail current in female rabbit ventricular myocytes is a key electrophysiological difference.
- This reduced current likely contributes to prolonged cardiac repolarization and increased risk of torsade de pointes in female rabbits.
- Findings highlight sex-specific mechanisms in cardiac electrophysiology and drug-induced arrhythmias.
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