DOES ADP REGULATE RESPIRATION FOLLOWING FERTILIZATION OF SEA URCHIN EGGS

The hypothesis that the ADP level regulates the respiration rate following fertilization of sea urchin eggs has been critically examined in the eggs of Strongylocentrotus purpuratus. Simultaneous measurements were made of (1) respiration rate, (2) adenine nucleotide levels and (3) energy utilization resulting from NAD kinase activity. Both respiration and energy utilization increase, but no changes in ATP, ADP, or AMP level were observed at the times of maximum respiratory activity. These findings do not support the hypothesis that respiration is limited by ADP. Alternate factors possibly controlling respiration include enzyme availability and Ca2+-uptake by mitochondria. © 1969.