Stimulation of living cells by femtosecond near-infrared laser pulses

Shigeki Iwanaga; Nicholas I. Smith; Katsumasa Fujita; Tomoyuki Kaneko; Masahito Oyamada; Tetsuro Takamatsu; Satoshi Kawata; Osamu Nakamura

doi:10.1117/12.478591

19 June 2003 Stimulation of living cells by femtosecond near-infrared laser pulses

Shigeki Iwanaga, Nicholas I. Smith, Katsumasa Fujita, Tomoyuki Kaneko, Masahito Oyamada, Tetsuro Takamatsu, Satoshi Kawata, Osamu Nakamura

Author Affiliations +

Proceedings Volume 4978, Commercial and Biomedical Applications of Ultrafast Lasers III; (2003) https://doi.org/10.1117/12.478591
Event: High-Power Lasers and Applications, 2003, San Jose, CA, United States

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.

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Shigeki Iwanaga, Nicholas I. Smith, Katsumasa Fujita, Tomoyuki Kaneko, Masahito Oyamada, Tetsuro Takamatsu, Satoshi Kawata, and Osamu Nakamura "Stimulation of living cells by femtosecond near-infrared laser pulses", Proc. SPIE 4978, Commercial and Biomedical Applications of Ultrafast Lasers III, (19 June 2003); https://doi.org/10.1117/12.478591

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