Preferential Expression of Ca2+-Stimulable Adenylyl Cyclase III in the Supraventricular Area, including Arrhythmogenic Pulmonary Vein of the Rat Heart

Ectopic excitability in pulmonary veins (PVs) is the major cause of atrial fibrillation. We previously reported that the inositol trisphosphate receptor in rat PV cardiomyocytes cooperates with the Na+-Ca2+ exchanger to provoke ectopic automaticity in response to norepinephrine. Here, we focused on...

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Bibliographic Details
Published in:Biomolecules (Basel, Switzerland) Switzerland), 2022-05, Vol.12 (5), p.724
Main Authors: Okamoto, Yosuke, Aung, Naing Ye, Tanaka, Masahiro, Takeda, Yuji, Takagi, Daichi, Igarashi, Wataru, Ishii, Kuniaki, Yamakawa, Mitsunori, Ono, Kyoichi
Format: Article
Language:English
Subjects:
Adenylate cyclase
adenylyl cyclase
Antibodies
Antigens
arrhythmia
atrial fibrillation
Automation
Body fat
Calcium (intracellular)
Calcium channels (L-type)
Calcium currents
Cardiac arrhythmia
Cardiomyocytes
Excitability
Fibrillation
Glucose
Heart
Immunohistochemistry
Inositol 1,4,5-trisphosphate receptors
Isotypes
Kinases
Myocytes
Na+/Ca2+ exchanger
Norepinephrine
Pacemakers
Proteins
pulmonary vein
supraventricular area
t-tubule
Tubules
Ventricle
Western blotting
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Summary:Ectopic excitability in pulmonary veins (PVs) is the major cause of atrial fibrillation. We previously reported that the inositol trisphosphate receptor in rat PV cardiomyocytes cooperates with the Na+-Ca2+ exchanger to provoke ectopic automaticity in response to norepinephrine. Here, we focused on adenylyl cyclase (AC) as another effector of norepinephrine stimulation. RT-PCR, immunohistochemistry, and Western blotting revealed that the abundant expression of Ca2+-stimulable AC3 was restricted to the supraventricular area, including the PVs. All the other AC isotypes hardly displayed any region-specific expressions. Immunostaining of isolated cardiomyocytes showed an enriched expression of AC3 along the t-tubules in PV myocytes. The cAMP-dependent response of L-type Ca2+ currents in the PV and LA cells is strengthened by the 0.1 mM intracellular Ca2+ condition, unlike in the ventricular cells. The norepinephrine-induced automaticity of PV cardiomyocytes was reversibly suppressed by 100 µM SQ22536, an adenine-like AC inhibitor. These findings suggest that the specific expression of AC3 along t-tubules may contribute to arrhythmogenic automaticity in rat PV cardiomyocytes.
ISSN:2218-273X
2218-273X
DOI:10.3390/biom12050724