Sarcoplasmic reticulum vesicles embedded in agarose gel exhibit propagating calcium waves

In different cell types, activation of signal transduction pathways leads t o the generation of calcium oscillations and/ or wa,es, Due to this importa nt impact for cellular function, calcium ma,;es are the subject of intensiv e investigations. To study interactions of cell organdies with no influence of the cell membrane, sarcoplasmic reticulum (SR) vesicles and well-couple d mitochondria were reconstituted. For the first time, we demonstrate the g eneration and propagation of calcium waves in a suspension of sarcoplasmic reticulum vesicles, embedded in an agarose gel. The propagation dynamics re semble those of calcium wa, fs in living cells. Moreover, the addition of w ell-coupled mitochondria leads to more pronounced and significantly faster propagating waves, demonstrating the importance of the mitochondrial Ca2+ t ransport. The experimental and simulation results indicate the resemblance of the in vitro system to an excitable medium. (C) 1999 Federation of Europ ean Biochemical Societies.