The role of ATP in the differential ability of Sr2+ to trigger Ca2+ oscillations in mouse and human eggs

Abstract At fertilization in mice and humans, the activation of egg is caused by a series repetitive Ca2+ oscillations which are initiated phospholipase-C(zeta)ζ that generates inositol-1,4,5-trisphophate (InsP3). can be triggered mature mouse eggs incubation Sr2+ containing medium, but this does not appear to effective human eggs. Here, we have investigated reason for apparent difference using eggs, failed fertilize after IVF or ICSI. Mouse incubated Ca2+-free, Sr2+-containing medium immediately underwent consistently undergo same medium. We tested InsP3-receptor (IP3R) sensitivity directly photo-release caged InsP3 found were about 10 times more sensitive than There no major differences store content between However, ATP concentration was higher compared When levels lowered pyruvate-free cause oscillations. pyruvate added back these increased induced. This suggests modulates ability stimulate IP3R-induced release suggest may unresponsive because they lower level cytosolic ATP.