SV channels dominate the vacuolar Ca2+ release during intracellular signaling.

Vacuoles have long been suggested to mediate a rise in the cytosolic free Ca(2+) during environmental signal transduction. This study addresses the issue of the control of vacuolar calcium release by some of the known signaling molecules such as IP(3), cADPR, ABA, ATP, cAMP, cGMP, H(2)O(2) and CaM. Over 30 concentrations and/or combinations of these signaling compounds were studied in a series of electrophysiological experiments involving non-invasive ion flux measurements (the MIFE) and patch-clamp techniques. Our results suggest that calcium, calmodulin and nucleotides cause calcium release via SV channels.