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Testosterone does not shorten action potential duration in Langendorff-perfused rabbit ventricles
Akira Ueoka1, Yen-Ling Sung1, Xiao Liu1
1Department of Cardiology, Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California.
Heart Rhythm
|June 18, 2022
Summary
Testosterone does not shorten ventricular repolarization in rabbit hearts, contrary to previous animal model findings. This study found testosterone may lengthen action potential duration at higher concentrations.
Area of Science:
- Cardiovascular Physiology
- Endocrinology
Background:
- Women exhibit longer QT intervals than men, potentially due to hormonal differences.
- Previous animal studies suggest testosterone shortens ventricular action potential duration (APD).
Purpose of the Study:
- To investigate if testosterone shortens APD in Langendorff-perfused rabbit ventricles.
- To test the hypothesis that testosterone influences ventricular repolarization.
Main Methods:
- Optical mapping of rabbit hearts with and without testosterone administration.
- Acute studies involved varying testosterone concentrations (1 nM to 3 μM).
- Chronic studies used testosterone pellets in female rabbits for 2-3 weeks.
Main Results:
- Testosterone did not shorten APD80 at any pacing cycle length in acute studies.
- Higher testosterone concentrations were associated with APD80 lengthening.
- Chronic testosterone pellet implantation did not alter QTc intervals and showed longer ventricular APD80 compared to controls.
Conclusions:
- Testosterone does not shorten ventricular repolarization in rabbit hearts.
- The findings do not support testosterone as a cause for sex differences in QT intervals based on APD shortening.
