Int J Arrhythm.  2017 Jun;18(2):77-84. 10.18501/arrhythmia.2017.012.

Ondansetron Inhibits Voltage-Gated K⁺ Current of Ventricular Myocytes from Pregnant Mouse

• Cui S
• Park H
• Park H
• Mun D
• Kim HE
• Yun N
• Joung B

• KMID: 2387536
• DOI: http://doi.org/10.18501/arrhythmia.2017.012

Abstract

BACKGROUND
The Htr3a antagonist, ondansetron, has been reported to prolong the QT interval and induce Torsades de pointes in the treatment of postoperative nausea and vomiting. To explore the mechanisms underlying these findings, we examined the effects of ondansetron on the mouse cardiac voltage-gated K⁺ (Kv) channel.
METHODS AND RESULTS
Ondansetron increased QT intervals in late pregnant (LP) mice. We measured the Kv channels in freshly isolated left ventricular (LV) myocytes from non-pregnant (NP) and late pregnant (LP) mice, using patch-clamp electrophysiology. Ondansetron blocked Kv current at a dose of 50 µM, and reduced the amplitude of peak current densities in a dose-dependent manner (0, 1, 5, 50 µM), in LP but not in NP mice. In contrast, serotonin and the Htr3 agonist, m-CPBG, increased Kv current densities in NP, but not in LP mice. Interestingly, during pregnancy, serum serotonin levels were markedly increased, suggesting the saturation of the effect of serotonin. Immunostaning data showed that Kv4.3 protein and Htr3a co-localize at the membrane and t-tubule of cardiomyocytes. Moreover, Kv4.3 membrane trafficking was enhanced in response to Htr3a-mediated serotonin stimulation in NP, but not in LP mice. Membrane analysis showed that serotonin enhances Kv4.3 membrane trafficking in NP, but not LP mice.
CONCLUSION
Ondansetron reduced Kv current densities, and reduced the Kv4.3 membrane trafficking in LP mouse ventricular cardiomyocytes. This data suggests that QT prolongation by ondansetron is mediated by the reduction of Kv current densities and Kv4.3 membrane trafficking.

Keyword

Ondansetron; Serotonin Receptor Type 3; Pregnancy; Voltage-Gated K⁺ (Kv) Current; Membrane Trafficking

MeSH Terms

Animals
Electrophysiology
Membranes
Mice*
Muscle Cells*
Myocytes, Cardiac
Ondansetron*
Postoperative Nausea and Vomiting
Pregnancy
Serotonin
Torsades de Pointes
Ondansetron
Serotonin