Study of intracellular calcium movement by time resolved image processing method.

点击翻译按钮获取中文摘要

Muscle contraction is known to be triggered by an increase of intracellular calcium ion concentration. The aim of the project was to observe whether calcium concentration increases homogeneously in a single skeleral muscle fiber using video-intensified microscopy system and image processor. Bioluminescent photoprotein, aequorin, was used as a calcium indicator, and phtomultiplier signal and image of aequorin luminescence were simultaneously recorded. 1. Aequorin was injected into a single skeletal muscle fiber and twitch was initiated. Luminescent spots were observed in the area where aequorin was injected. If several images of twitches were added, no substantial difference of brightness was observed in the aequorin injected area. 2. In tetanized skeletal muscle fibers (40 Hz, 1 sec), tension was sustained and no significant difference of brightness was recognized after adding several images in the aequorin injected area. Similar result was obtained when the sarcomere was changed form 2.4<micrn>m to 3.6<micrn>m. Caffeine known to release calcium from sarcoplasmic reticulum caused contracture, and luminescent spots which appeared in the surface of the preparation spreaded into the center of the fiber. Finally, the aequorin loaded area became bright homogeneously. These results indicate that physiological activation dose not cause inhomogeneity of intracellular calcium concentration under the limitation of microscopic and video resolution and that caffeine which diffuses into the fiber causes inhomogeneous calcium ion release. Further study is required to clarify the condition which causes inhomogeneous activation and its significance