| Title: | Pharmacological nNOS inhibition modified small-conductance Ca2+-activated K plus channel without altering Ca2+dynamics |
| Authors: | Koya, Taro Browse this author |
| Watanabe, Masaya Browse this author →KAKEN DB |
| Natsui, Hiroyuki Browse this author |
| Kadosaka, Takahide Browse this author |
| Koizumi, Takuya Browse this author |
| Nakao, Motoki Browse this author |
| Hagiwara, Hikaru Browse this author |
| Kamada, Rui Browse this author |
| Temma, Taro Browse this author |
| Anzai, Toshihisa Browse this author →KAKEN DB |
| Keywords: | atrial fibrillation |
| neuronal nitric oxide synthase |
| small-conductance Ca2+-activated K plus channel |
| Issue Date: | 1-Nov-2022 |
| Publisher: | American Physiological Society |
| Journal Title: | American journal of physiology. Heart and circulatory physiology |
| Volume: | 323 |
| Issue: | 5 |
| Start Page: | H869 |
| End Page: | H878 |
| Publisher DOI: | 10.1152/ajpheart.00252.2022 |
| Abstract: | Atrial fibrillation (AF) is associated with electrical remodeling processes that promote a substrate for the maintenance of AF. Although the small-conductance Ca2+-activated K+ (SK) channel is a key factor in atrial electrical remodeling, the mechanism of its activation remains unclear. Regional nitric oxide (NO) production by neuronal nitric oxide synthase (nNOS) is involved in atrial electrical remodel-ing. In this study, atrial tachyarrhythmia (ATA) induction and optical mapping were performed on perfused rat hearts. nNOS is pharma-cologically inhibited by S-methylthiocitrulline (SMTC). The influence of the SK channel was examined using a specific channel inhibitor, apamin (APA). Parameters such as action potential duration (APD), conduction velocity, and calcium transient (CaT) were evaluated using voltage and calcium optical mapping. The dominant frequency was examined in the analysis of AF dynamics. SMTC (100 nM) increased the inducibility of ATA and apamin (100 nM) mitigated nNOS inhibition-induced arrhythmogenicity. SMTC caused abbrevia-tions and enhanced the spatial dispersion of APD, which was reversed by apamin. By contrast, conduction velocity and other parame-ters associated with CaT were not affected by SMTC or apamin administration. Apamin reduced the frequency of SMTC-induced ATA. In summary, nNOS inhibition abbreviates APD by modifying the SK channels. A specific SK channel blocker, apamin, mitigated APD abbreviation without alteration of CaT, implying an underlying mechanism of posttranslational modification of SK channels. NEW & NOTEWORTHY We demonstrated that pharmacological nNOS inhibition increased the atrial arrhythmia inducibility and a specific small-conductance Ca2 +-activated K+ channel blocker, apamin, reversed the enhanced atrial arrhythmia inducibility. Apamin mitigated APD abbreviation without alteration of Ca2+ transient, implying an underlying mechanism of posttranslational modification of SK channels. |
| Type: | article |
| URI: | http://hdl.handle.net/2115/90688 |
| Appears in Collections: | 北海道大学病院 (Hokkaido University Hospital) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)
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