Inhibitors of mitochondrial ATP production at the time of compaction improve development of in vitro produced porcine embryos

The relationship between partial inhibition of mitochondrial ATP production during the peri-compaction stage and porcine embryonic development was stu died. In vitro produced porcine compact morulae were cultured for two days under conditions that should inhibit ATP production via oxidative phosphory lation. The culture conditions included supplementation of the culture medi um with sodium azide (NaN3), an oxidative phosphorylation inhibitor; incuba tion in the presence of 2,4-dinitrophenol (DNP), an uncoupler of oxidative phosphorylation; or incubation under 5% O-2 concentration. NaN3 (10-20 muM) increased the average nuclear number found in the resulting blastocysts (P < 0.05). The embryos developed in the presence of 100 <mu>M DNP formed bla stocysts at a significantly higher incidence than the control embryos (P < 0.001); the average nuclear number found in these blastocysts was also high er (P < 0.005). When these treatments were applied from the 1-cell stage th ey proved to be detrimental. Elevations in the frequency of blastocyst form ation (P < 0.05), and in the average nuclear number per blastocyst (P < 0.0 01) were also measured when compact morulae were incubated in an atmosphere containing 5% vs. 20% O-2 NaN3 or DNP did not have negative effects on lon g term development: the treated embryos were able to form viable conceptuse s by day 30 after being transferred into recipients. The data indicate that transient inhibition of mitochondrial ATP production is advantageous for p orcine embryonic development in vitro. (C) 2001 Wiley-Liss, Inc.