Shifts in ATP synthesis during preimplantation stages of mouse embryos

Abstract

The actual and potential activities of the cytochrome system were studied in cleavage stage mouse embryos. Activities were determined by assaying embryos for total ATP and the rates of [32P]ATP synthesis both before and after their incubation in medium supplemented either with an energy coupling site inhibitor (antimycin, amytal or cyanide) or with the FADH linked substrate, succinate. The data indicate that there are 3 major shifts in the mode of ATP production during preimplantation stages: the first, between the 2 cell and late 4 cell stages; the 2nd, between the 8 cell and late morula stages; and the 3rd, between the late morula and late blastocyst stages. These data are discussed in relation to studies on the energy metabolism of cleavage and blastocyst stage mouse embryos.