Journal of Pharmacological Sciences (Jan 2009)

Involvement of the Na+/Ca2+ Exchanger in the Automaticity of Guinea-Pig Pulmonary Vein Myocardium as Revealed by SEA0400

  • Iyuki Namekata,
  • Yayoi Tsuneoka,
  • Akira Takahara,
  • Hideaki Shimada,
  • Takahiko Sugimoto,
  • Kiyoshi Takeda,
  • Midori Nagaharu,
  • Koki Shigenobu,
  • Toru Kawanishi,
  • Hikaru Tanaka

Journal volume & issue
Vol. 110, no. 1
pp. 111 – 116

Abstract

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Abstract.: We examined the involvement of the Na+/Ca2+ 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 Ca2+ 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 Ca2+ transients, which were inhibited by SEA0400, as well as ryanodine. These results provide pharmacological evidence that the Na+/Ca2+ exchanger underlies the automaticity of the pulmonary vein myocardium. Keywords:: pulmonary vein myocardium, Na+/Ca2+ exchanger, automaticity