Evidence for the De Novo Synthesis of Erythropoietin in Hypoxic Rats

Significant increases in the serum erythropoietin of male rats occur after the end of a brief hypoxic exposure. These increases in the hormone are almost completely abolished when the kidneys are removed after the hypoxic exposure. Injection of puromycin or cycloheximide after the hypoxic exposure significantly decreases the subsequent increases in serum erythropoietin titers, whereas injections of actinomycin D at this time have no significant effect on erythropoietin levels. Injections of actinomycin D before the hypoxic exposure prevent the increase in serum erythropoietin that normally occurs. These findings suggest that a brief period of hypoxia initiates a DNA-dependent RNA synthesis that regulates the de novo ribosomal synthesis of protein(s) involved in the biogenesis of erythropoietin and that the kidney is essential for these reactions to occur.