Fura-2 Imaging of Intracellular Free Calcium Dynamics in Excitable Cells

Intracellular free Ca2+ concentration ([Ca 2+ ] 1) maps were obtained from excitable cells loaded with fura-2, using improved digital image fluorescence microscopy. New procedures allowed to get fast sampling of [Ca 2+ ] 1 maps (25 maps/sec) and real spatial distribution of [Ca 2+ ] 1 changes only. The spatial heterogeneity of [Ca 2+ ] 1 changes in skeletal muscle cells stimulated by KCl depolarisation is interpreted as a non-uniform distribution of functional sarcoplasmic reticulum.