Influence of the ionic composition of the medium on the sensitivity of fertilized sea urchin ova to neuropharmacological preparations.

The removal of Ca2+ from the incubation medium leads to an increase in the sensitivity of early sea urchin embryos to neuropharmacological blockers of development. The removal of SO4-2-, half of the K+, as well as an increase in the Ca2+ content, have no effect on the sensitivity of fertilized eggs to these preparations. The sensitivity to puromycin, colchicine, triton X-100, and 2, 4-dinitrophenol is unchanged by the removal of Ca2+ from the medium. The protective action of exogenous monoamines and acetylcholine is not manifested in a solution that does not contain Ca2+. Serotonin, catecholamines, and acetylcholine have no appreciable effect on cleavage either in sea water of normal composition or in water without Ca2+.