Measurement of intracellular calcium dynamics during muscle contraction

Intracellular calcium concentration ([Ca2+]i) was measured by use of the fluorescence microscopy with a calcium sensitive dye(FURA-2) in isolated muscle cells of a cricket oval duct. These cells spontaneously contracted in the incubating chamber. Intracellular calcium dynamics was evaluated for the fluorescence images simultaneously represented as cell contraction. It is found that the cell shortening during contraction correlated with the [Ca2+]i rise especially in a tip area of the cell. From this result we confirmed that the calcium inflow at the cell tip firstly induced the sequence of the muscle contraction.