Inhibitory Effects of Diltiazem and Verapamil, Calcium Antagonists, on Fertilization-Induced Increase in the Phosphorylase Reaction in Echiuroid Eggs: (diltiazem/verapamil/phosphorylase/glycolysis/echiuroid eggs).

The calcium antagonists diltiazem and verapamil at 100 μM caused considerable inhibition of the glycolysis system in recently fertilized eggs of the echiuroid, Urechis unicinctus. The levels of glycolytic intermediates in eggs were found to be higher 5 min after insemination than before fertilization while the levels of adenine nucleotides and inorganic phosphate were almost the same before and after fertilization. Addition of diltiazem or verapamil 30 sec after insemination did not inhibit fertilization, but resulted in maintenance of as low levels of glycolytic intermediates as in unfertilized eggs.