The effects of inhibitors of energy metabolism on the growth of one-cell rabbit ova to blastocysts in vitro.

Fertilized 1-cell rabbit ova were cultured in the presence of three oxidative phosphorylation inhibitors (cyanide, 2,4-dinitrophenol and oligomycin), two tricarboxylic acid (TCA) cycle inhibitors (malonate and fluoroacetate) and one glycolytic inhibitor (2-deoxyglucose). All three oxidative phosphorylation inhibitors killed ova at the 1-cell stage and the damage caused by each was similar. Malonate was non-toxic at all concentrations whereas some concentrations of fluoroacetate stopped growth at the 1-cell stage. This toxic effect could, in some circumstances, be reversed by the presence of acetate but not of glucose. 2-Deoxyglucose blocked only the transition from morula to blastocyst, and this was prevented by the addition of glucose to the medium; pyruvate, ribose, glycerol, and L-alpha-glycerol phosphate were ineffective. An active oxidative phosphorylation system and tricarboxylic cycle appear to be present and essential in the rabbit embryo from the 1-cell stage, but glycolysis may not be essential until blastocyst formation.