Involvement of the Na(+)/Ca(2+) exchanger in the automaticity of guinea-pig pulmonary vein myocardium as revealed by SEA0400.
We examined the involvement of the Na(+)/Ca(2+) exchanger in the automaticity of the pulmonary vein myocardium with a specific inhibitor, SEA0400. Action potentials were recorded from the myocardial layer of isolated guinea-pig pulmonary vein preparations, and Ca(2+) transients were recorded from the cardiomyocytes. Spontaneous electrical activity was observed in 17.7% of the preparations, which was inhibited by either SEA0400 or ryanodine. In quiescent preparations, ouabain induced electrical activity and spontaneous Ca(2+) transients, which were inhibited by SEA0400, as well as ryanodine. These results provide pharmacological evidence that the Na(+)/Ca(2+) exchanger underlies the automaticity of the pulmonary vein myocardium.
Namekata
Iyuki
I
Department of Pharmacology, Toho University Faculty of Pharmaceutical Sciences, Japan. iyuki@phar.toho-u.ac.jp
Tsuneoka
Yayoi
Y
Takahara
Akira
A
Shimada
Hideaki
H
Sugimoto
Takahiko
T
Takeda
Kiyoshi
K
Nagaharu
Midori
M
Shigenobu
Koki
K
Kawanishi
Toru
T
Tanaka
Hikaru
H
D000200:Action Potentials / Q000187:drug effects; D000814:Aniline Compounds; D000818:Animals; D002316:Cardiotonic Agents / Q000494:pharmacology; D005260:Female; D006168:Guinea Pigs; D006321:Heart / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D008297:Male; D018613:Microscopy, Confocal; D010042:Ouabain / Q000494:pharmacology; D010647:Phenyl Ethers; D011667:Pulmonary Veins / Q000187:drug effects / Q000502:physiology*; D012433:Ryanodine / Q000494:pharmacology; D019831:Sodium-Calcium Exchanger / Q000037:antagonists & inhibitors* / Q000502:physiology*
D000814:Aniline Compounds; D002316:Cardiotonic Agents; D010647:Phenyl Ethers; C430918:SEA 0400; D019831:Sodium-Calcium Exchanger; D012433:Ryanodine; D010042:Ouabain