Our previous studies have shown a salutary effect of adenosine triphosphate-magnesium chloride (ATP-MgCl2) administered to animals in shock. The presence of adenine nucleotide converting enzymes on cell surfaces and the ability of nucleotides to act at the cell surface have been recognized also. To investigate the fate of administered or externally applied ATP and to determine whether it would be subjected to increased degradation with shock, the soleus muscles from rats subjected to hemorrhagic shock and from control animals were incubated in the presence of ATP, adenosine diphosphate (ADP), or adenosine monophosphate (AMP) with MgCl2. Comparable degradation of the added nucleotides was observed with both control muscles and those from bled animals. Adenylate kinase activity was detected to the same extent in the medium after incubation with both groups of muscles, but other enzymes were not, suggesting that the latter enzymes were located on the exterior surface of the muscle cell. Thus with shock there was no increase in the breakdown of the nuceotides by the enzymes on the muscle surface (ATPase, AMPdeaminase) or the cellular enzyme, adenylate kinase. © 1975.