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Proceedings Paper

Stimulation of living cells by femtosecond near-infrared laser pulses
Author(s): Shigeki Iwanaga; Nicholas I. Smith; Katsumasa Fujita; Tomoyuki Kaneko; Masahito Oyamada; Tetsuro Takamatsu; Satoshi Kawata; Osamu Nakamura
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Paper Abstract

We have demonstrated that intracellular Ca2+ waves in a living HeLa cell can be induced by femtosecond near-infrared laser pulses. In this paper, we present the results of investigation on the process of the Ca2+ wave generation using pharmacological methods to determine generation mechanisms. A mode-locked Ti:Sapphire laser (780 nm, 80 fs, 82 MHz) was used as a wave-triggering light source. The laser beam was focused into HeLa cells by using a water immersion objective lens (NA 0.9). Ca2+ waves were visualized by using a fluorescent Ca2+ indicator (Fluo-4) and monitored by a fluorescence microscope. Three mechanisms for the Ca2+ wave generation were considered; (1) Ca2+ flow into cells by destruction of the cell membrane, (2) mechanical stress by shock waves associated with the laser absorption, and (3) the leaking of Ca2+ through the destruction of intracellular Ca2+ stores. To investigate the mechanisms, we have performed experiments to determine the dependence of the probability of Ca2+ wave generation with two kinds of extracellular solutions; (a) a Ca2+ free extracellular solution (by use of EGTA), and (b) a solution containing U-73122 to inhibit the response to shockwave-based mechanical effects. From these experimental results, we can conclude the main mechanism of Ca2+ wave generation by laser irradiation is due to the leaking of Ca2+ through the destruction of intracellular Ca2+ stores.

Paper Details

Date Published: 19 June 2003
PDF: 7 pages
Proc. SPIE 4978, Commercial and Biomedical Applications of Ultrafast Lasers III, (19 June 2003); doi: 10.1117/12.478591
Show Author Affiliations
Shigeki Iwanaga, Osaka Univ. (Japan)
Nicholas I. Smith, Osaka Univ. (Japan)
Katsumasa Fujita, Osaka Univ. (Japan)
Tomoyuki Kaneko, Osaka Univ. (Japan)
Masahito Oyamada, Kyoto Prefectural Univ. of Medicine (Japan)
Tetsuro Takamatsu, Kyoto Prefectural Univ. of Medicine (Japan)
Satoshi Kawata, Osaka Univ. (Japan)
Osamu Nakamura, Osaka Univ. (Japan)

Published in SPIE Proceedings Vol. 4978:
Commercial and Biomedical Applications of Ultrafast Lasers III
Joseph Neev; Andreas Ostendorf; Christopher B. Schaffer, Editor(s)

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