Loss of epinephrine stimulated synthesis of cyclic adenosine 3':5' monophosphate during maturation of rabbit and human reticulocytes.

The adenylate cyclase activity of rabbit reticulocytes is localized in the stroma. Rabbit reticulocytes are four times more active than mature erythrocytes in transforming in situ formed [14C] adenosine triphosphate into [14C] cyclic adenosine 3':5'-monophosphate. Similarly, anaemic human red blood cells show higher activity in effecting this transformation. The adenylate cyclase activity is stimulated by epinephrine, 40% in rabbit reticulocytes, and 70-80% in anaemic human RBC but not in erythrocytes. Both the reticulocytes and erythrocytes can bind [14C] epinephrine, but the reticulocytes bind a relatively large amount. A glycogen phosphorylase that can be activated by cyclic adenosine 3':5'-monophosphate is detected only in reticulocytes. Both reticulocytes and erythrocytes contain a phosphodiesterase which can hydrolyse cyclic 3':5'-adenosine monophosphate and which is activated by imidazole and inhibited by methyl xanthines.