Studies on a pancreatic cardiodepressant factor.

Myocardial depressant factor (MDF) was isolated from dog pancreas after incubation at 37 degrees C for 2 hr. A highly purified preparation of MDF was obtained by paper chromatography and high voltage electrophoresis. After paper chromatography of crude homogenates of the pancreatic tissue, cardiodepressant activity was found in spot F. High voltage electrophoresis of spot F produced five separate fractions. Bioassay using isolated perfused hearts and cultures of myocytic tissue showed that only one of these spots was associated with MDF activity. This spot contained a peptide with a molecular weight of 1000-2500 consisting of nine amino acids.