Intracellular Microinjection of Anticalmodulin Drugs Does not Inhibit the Cortical Reaction Induced by Fertilization, Ionophore A 23187 or Injection of Calcium Buffers in Sea Urchin Eggs

The drugs, fluphenazine, chlorpromazine, dibucaine, propranolol, vinblastine and W7N-(6-arninohexyl)-5 chloro-1-napthalene-sulfonamide], which have been shown to prevent formation of the ternary activated complex of Ca⁺⁺-calmodulin with several soluble or membrane proteins, inhibit the cortical reaction induced by fertilization, by ionophore A 23187 or by the microinjection of Ca⁺⁺ buffers when applied from outside to sea urchin eggs. In contrast, direct intracellular microinjection of these drugs, even at concentrations much exceeding their I₅₀ for external application, does not suppress elevation of the fertilization membrane, although it prevents cleavage after fertilization. The implication is that intracellular calmodulin is not the receptor of Ca⁺⁺ in the Ca⁺⁺-dependent exocytosis of cortical granules induced by fertilization, by ionophore, or by the micro-injection of calcium buffers.