Cardio-accelerating factors from the terminal abdominal ganglion of the American cockroach

Saline extracts of the terminal abdominal ganglion stimulate the contraction of the cockroach heart. Gel filtration of P-4 and P-10 polyacrylamide gel separates the active components into two fractions. One of these appears to be a peptide(s) of a molecular weight between 3500 and 7500 whereas the other is much smaller. Further fractionation of the smaller component on G-10 Sephadex yields two peaks of activity. The smaller of the two correponds to a molecular weight of approximately 150. The larger absorbs in u.v. light and is thought to be aromatic in nature.Oscilloscope recordings show a heartbeat of increased amplitude after the addition of the larger peptide. Bathing the heart with the smallest component yields an increased frequency of contraction similar to that observed for authentic acetylcholine.