A note on the mechanism of action of UV-irradiation of amphibian embryos

Summary The actions on amphibian embryos of UV-irradiation, exposure to Li⁺ or exposure to ouabain show interesting parallels with their effects on spontaneous release at the presynaptic terminals of the neuromuscular junction. It is suggested that these treatments serve to raise intracellular Ca²⁺ (Ca²⁺ _i) in these examples, and that UV-promoted abnormalities in embryogenesis are a consequence of changes in Ca²⁺]_i at critical stages in development.