Stimulation of Uterine Contraction by Extracts of the Cockroach, Periplaneta

Blood and extracts of gut of the American cockroach, Periplaneta americana, powerfully stimulate contractions of the isolated rat uterus. The contractions are characterized by long latency and a prolonged relaxation phase having superimposed rhythmic contractions. Evidence indicates that the stimulating factor is not acetylcholine, 5-hydroxytryptamine, histamine, or substance P. The active factor is heat labile and nondialyzable.