It has been reported that the effect of A23187 is the direct induction of extracellular calcium influx and intracellular H+ efflux, thus resulting in increases in [Ca2+]j and intracellular pH ([pH],). Although in the present study we did not examine the [рЩ, [Ca2′ ], measurement indicated that activation of pig oocytes by A23187 was related to increased [Ca2′]; and that this increase was dependent upon the concentration of A23187 used. Also we found that the peak ratio values of the transients were positively correlated to the ability of oocytes to release CGs and form a pronucleus(ei). In addition, the A23187-induced cortical reaction modifies ZP, which in turn participate in inhibition of penetration of ZP-intact oocytes by spermatozoa. birth control pills
Plasma membrane penetration, however, was not inhibited by the A23187-induced cortical reaction. This is the first report of a study examining the mechanism of activation in pig oocytes with A23187, and the results indicate that A23187-induced cortical and zona reactions are functional in pig oocytes matured and activated in vitro under the conditions of the present study.