A pharmacological study of calcium flux mechanisms in the tannin vacuoles ofMimosa pudica L. motor cells

Summary When treated with various calcium-active agents, the volume changes in the tannin vacuoles of the abaxial (lower) motor cells in the sensitiveMimosa pudica L. correspond to the movement of the primary pulvinus. The calcium pump inhibitors, sodium metavanadate and erythrosin B, significantly inhibited the rate of recovery in both the in vivo and in vitro examinations, while the calcium channel blocker, verapamil, inhibited the closing response. Bay-K 8644 enhanced the in vivo effect and induced the in vitro effect, therefore appearing to be an agonist of the voltage regulated calcium channels in the tannin vacuoles. These observations support the hypothesis that calcium channels in the tannin vacuole membrane underly the thigmonastic response and pumps in the tannin vacuole membrane are involved in the mechanisms underlying recovery.Abbreviations MP mechanical perturbation - Na Vanadate sodium metavanadate