Development of membrane sensitivity to the parthenogenetic agent calcium ionophore A23187 during meiotic maturation in the hamster oocyte

Abstract

The response to the parthenogenetic agent Ca‐ionophore A23187 was studied in hamster oocytes undergoing meiotic maturation, by using electrophysiological techniques. Following germinal vesicle breakdown, the activating agent induces a long‐lasting hyperpolarization accompanied by an increased membrane conductance. The duration of the response progressively shortens during the long metaphase I stage. Terminal metaphase I oocytes respond to A23187 by a hyperpolarization that is very similar to that seen in metaphase II oocytes. The ionic mechanism of the change in the membrane sensitivity to A23187 during meiotic maturation is discussed.