Abstract
Polyacrylamide gel electrophoresis at neutral pH, 0°C, was used to test the identity of prolactin derived from serum and pituitary extracts of rats. Animals were studied after treatment with perphenazine, a prolactin releasing agent, and during post partum lactation. After gel electrophoresis, the position on the gel of prolactin activity was determined by the pigeon crop-sac bioassay. The biologically active prolactin exhibited identical electrophoretic mobility, whether derived from serum or pituitary, of either normal lactating or perphenazine treated rats.