Inositol trisphosphate stimulates the release of calcium from intact vacuoles isolated from Acer cells

On addition of inositol trisphosphate, intact vacuoles isolated from Acer pseudoplatanus cell suspension cultures release part of their calcium content. The process was specific, dose-dependent (IC₅₀ = 0.2μM) and was inhibited by an intracellular calcium antagonist. The calcium efflux elicited by inositol trisphosphate increased with the age of the cell suspension cultures, the maximum effect being obtained when the cultures reached the stationary phase. It is suggested that vacuoles play a role as an endocellular calcium store that is responsive to inositol trisphosphate in plants.