Irradiance dependence of the conduction block of an in vitro cardiomyocyte wire

Emiyu Ogawa, Mariko Kurotsu, Tsunenori Arai

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


Background To obtain therapeutic condition precisely by in vitro experiment, we studied the irradiance dependence of the electrical conduction blockage caused by a photodynamic reaction using a high extracellular concentration of talaporfin sodium on a novel in vitro cardiomyocyte electrical conduction wire. Methods The cardiomyocyte wires were constructed on patterned cultivation cover glass, which had cultivation areas 60 μm in width, and a maximum length of 10 mm. The talaporfin sodium concentration was set to 20 μg/mL. The photodynamic reaction with a high extracellular photosensitizer concentration was performed with a short time interval (approximately 15 min) between photosensitizer exposure and irradiation. A 663-nm laser was applied to the cardiomyocyte wire, and the irradiance was varied between 3 and 120 mW/cm2. The cardiomyocyte electrical conduction was evaluated using the cross-correlation function of intracellular Ca2+ probe fluorescence brightness from an upper and lower section outside the laser irradiation area of a wire every 10 s, which lasted up to 600 s. Results The onset of electrical conduction blockage was defined by an 85% decrease in the cross-correlation function, compared with its initial value. The time for the electrical conduction blockage decreased from 600 to 300 s as the irradiance was increased. Also, the probability of electrical conduction blockage was found to increase with increasing irradiance. Conclusions We found a strong dependence on the irradiance for the time and probability of electrical conduction blockage.

Original languageEnglish
Pages (from-to)93-97
Number of pages5
JournalPhotodiagnosis and Photodynamic Therapy
Publication statusPublished - 2017 Sept


  • Cross-correlation function
  • Electrical conduction
  • Interstitial fluid
  • Myocardial cell
  • Photodynamic reaction
  • Talaporfin sodium

ASJC Scopus subject areas

  • Biophysics
  • Oncology
  • Dermatology
  • Pharmacology (medical)


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