[Mechanism of the protective action of acetylcholine and serotonin against their cytotoxic antagonists].

By means of biological testing on supersensitive embryos of the sea-urchin Arbacia lixula, it has been shown that the eggs and embryos of the sea-urchin Paracentrotus lividus incubated in solutions of cytotoxic neuropharmacological drugs (cholino- and serotoninolytics), accumulate the latter. During the first (rapid) stage of binding, a level is reached which is 2-6 times higher than the external concentration; during the second stage of binding, this level gradually increases up to the values which are 8-12 times higher than the external concentration. The protecting action of exogenous acetylcholine and serotonin against the drugs studied does not inhibit their accumulation in embryonic cells. Therefore this protecting action is due to the decrease in the sensitivity of embryos to neurophysiological drugs. The protecting effect of endogenous factor produced by eggs and embryos is associated with the inhibition or abolition of the second stage of binding of cytotoxic neuropharmacological drugs.