Repetition-rate-dependent oxygen consumption modifies cytotoxicity in photodynamic therapy using pulsed light

Satoko Kawauchi, Yuji Morimoto, Hiroshi Asanuma, Hiroyuki Sato, Tsunenori Arai, Shunichi Sato, Isao Sakata, Takeshi Takemura, Susumu Nakajima, Makoto Kikuchi

Research output: Contribution to journalConference articlepeer-review


We studied the repetition-rate dependence of PDT cytotoxicity and relation between PDT cytotoxicity and both oxygen consumption and photobleaching during PDT in vitro. Mice renal carcinoma cells were incubated with second-generation photosensitizer, PAD-S31, and were irradiated with 670-nm nanoseconds pulsed light from YAG-OPO system. Four repetition rates of 30, 15, 5 and 3 Hz were investigated, provided that the incident peak intensity and the total light dose adjusted to 1.2 MW/cm2 and 40 J/cm2, respectively. We found limited cytotoxicity about 40% at 30 and 15 Hz and sufficient cytotoxicity about 80% at 5 and 3 Hz. The oxygen measurement during irradiation revealed that the 5- and 3-Hz irradiation caused slow oxygen consumption, while rapid oxygen consumption followed by a rapid recovery of oxygenation at 30 and 15 Hz. Interestingly, the fluorescence measurement during irradiation also demonstrated that photobleaching discontinued in the same period of oxygen recovery at 30 and 15 Hz. These discontinued oxygen consumptiona and photobleaching at 30 and 15 Hz might have limited effective total fluence and resulted in suppressed cytotoxicity. These results suggest that the PDT efficacy using a pulsed laser significantly depends on the pulse repetition rate probably due to different oxygen consumption process during PDT.

Original languageEnglish
Pages (from-to)125-130
Number of pages6
JournalProceedings of SPIE - The International Society for Optical Engineering
Publication statusPublished - 2003
Externally publishedYes
EventOptical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XII - San Jose, CA, United States
Duration: 2003 Jan 252003 Jan 26


  • Oxygen consumption
  • PAD-S31
  • Photobleaching
  • Photodynamic therapy
  • Repetition rate

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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