Reversible inhibition of cytoplasmic streaming by intracellular Ca2+ in tonoplast-free cells ofChara australis

The effect of the intracellular concentration of Ca2+ on the cytoplasmic streaming of tonoplast-free cells ofChara australis was studied by intracellular perfusion. The perfusion media contained 1 mM Mg · ATP. Both cell ends were cut and left open. Media of different Ca2+ concentrations were perfused through the cell and the rate of the cytoplasmic streaming just after perfusion was measured. The critical concentration of Ca2+ for inhibiting the streaming was 5 × 10−4M, which was substantially higher than that found earlier byWilliamson (1975) andHayamaet al. (1979). Recovery from the inhibition occurred, though not completely, by removing Ca2+.