title: Microscopic heat pulse-induced calcium dynamics in single WI-38 fibroblasts.
abstract: Temperature-sensitive Ca(2+) dynamics occur primarily through transient receptor potential channels, but also by means of Ca(2+) channels and pumps on the endoplasmic reticulum membrane. As such, cytoplasmic Ca(2+) concentration ([Ca(2+)]cyt) is re-equilibrated by changes in ambient temperature. The present study investigated the effects of heat pulses (heating duration: 2 s or 150 s) on [Ca(2+)]cyt in single WI-38 fibroblasts, which are considered as normal cells. We found that Ca(2+) burst occurred immediately after short (2 s) heat pulse, which is similar to our previous report on HeLa cells, but with less thermosensitivity. The heat pulses originated from a focused 1455-nm infrared laser light were applied in the vicinity of cells under the optical microscope. Ca(2+) bursts induced by the heat pulse were suppressed by treating cells with inhibitors for sarco/endoplasmic reticulum Ca(2+) ATPase (SERCA) or inositol trisphosphate receptor (IP3R). Long (150 s) heat pulses also induced Ca(2+) bursts after the onset of heating and immediately after re-cooling. Cells were more thermosensitive at physiological (37°C) than at room (25°C) temperature; however, at 37°C, cells were responsive at a higher temperature (ambient temperature+heat pulse). These results strongly suggest that the heat pulse-induced Ca(2+) burst is caused by a transient imbalance in Ca(2+) flow between SERCA and IP3R, and offer a potential new method for thermally controlling Ca(2+)-regulated cellular functions.
authors: Department of Pure and Applied Physics, Graduate School of Advanced Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan; Institute of Medical Biology, Agency for Science Technology & Research (ASTAR), 8A Biomedical Grove, #06-06 Immunos, Singapore 138648, Singapore.
authors: Hideki
authors: H
authors: Itoh
authors: Department of Physics, Faculty of Advanced Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan.
authors: Kotaro
authors: K
authors: Oyama
authors: Waseda Bioscience Research Institute in Singapore (WABIOS), 11 Biopolis Way, #05-02 Helios, Singapore 138667, Singapore; Organization for University Research Initiatives, Waseda University, 513 Waseda Tsurumaki-cho, Shinjuku-ku, Tokyo 162-0041, Japan.
authors: Madoka
authors: M
authors: Suzuki
authors: Department of Pure and Applied Physics, Graduate School of Advanced Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan; Department of Physics, Faculty of Advanced Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan; Waseda Bioscience Research Institute in Singapore (WABIOS), 11 Biopolis Way, #05-02 Helios, Singapore 138667, Singapore; Organization for University Research Initiatives, Waseda University, 513 Waseda Tsurumaki-cho, Shinjuku-ku, Tokyo 162-0041, Japan.
authors: Shin'ichi
authors: S
authors: Ishiwata
keywords: ER; IR laser; calcium imaging; temperature change; thermometer sheet