Sensitivity of sea urchin early embryos to antagonists of acetylcholine and monoamines

Early embryos of A. lixula are 10–800 times more sensitive to several neuropharmaca than are early embryos of 6 other studied species of sea urchins. Of 53 neuropharmaca studied, 25 were found hyperactive; of 19 other inhibitors of development (mitotic and metabolic poisons) only antimycin A was hyperactive for A. lixula. Both hyperactive neuropharmaca and neuropharmaca with normal activity suppress cleavage divisions and inhibit protein biosynthesis acting as antagonists of intracellular acetylcholine and monoamines. The mechanism responsible for the normal sensitivity and hypersensitivity of early sea urchin embryos is discussed.