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Testosterone does not shorten action potential duration in Langendorff-perfused rabbit ventricles.
- Source :
-
Heart rhythm [Heart Rhythm] 2022 Nov; Vol. 19 (11), pp. 1864-1871. Date of Electronic Publication: 2022 Jun 15. - Publication Year :
- 2022
-
Abstract
- Background: Women have longer baseline QT intervals than men. Because previous studies showed that testosterone and 5α-dihydrotestosterone shorten the ventricular action potential duration (APD) in animal models, differential testosterone concentrations may account for the sex differences in QT interval.<br />Objective: The purpose of this study was to test the hypothesis that testosterone shortens the APD in Langendorff-perfused rabbit ventricles.<br />Methods: We performed optical mapping studies in hearts with or without testosterone administration. Acute studies included 26 hearts using 2 different protocols, including 17 without and 9 with atrioventricular (AV) block. For chronic studies, we implanted testosterone pellets subcutaneously in 7 female rabbits for 2-3 weeks before optical mapping studies during complete AV block. Six rabbits without pellet implantation served as controls.<br />Results: The hearts in the acute studies were paced with a pacing cycle length (PCL) of 200-300 ms and mapped at baseline and after administration of 1 nM, 10 nM, 100 nM, and 3 μM of testosterone. There was no shortening of APD <subscript>80</subscript> at any PCL. Instead, a lengthening of APD <subscript>80</subscript> was noted at higher concentrations. There were no sex differences in testosterone responses. In chronic studies, heart rates were 136 ± 5 bpm before and 148 ± 9 bpm after (P = .10) while QTc intervals were 314 ± 9 ms before and 317 ± 99 ms after (P = .69) testosterone pellet implantation, respectively. Overall, ventricular APD <subscript>80</subscript> in the pellet group was longer than in the control group at 300- to 700-ms PCL.<br />Conclusion: Testosterone does not shorten ventricular repolarization in rabbit hearts.<br /> (Copyright © 2022 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)
Details
- Language :
- English
- ISSN :
- 1556-3871
- Volume :
- 19
- Issue :
- 11
- Database :
- MEDLINE
- Journal :
- Heart rhythm
- Publication Type :
- Academic Journal
- Accession number :
- 35716858
- Full Text :
- https://doi.org/10.1016/j.hrthm.2022.06.012