Objective: 

Apelin is a novel peptide hormone related to some metabolic and physiological processes including reproductive system. We have previously demonstrated for the first time that apelin has a stimulatory effect on myometrial contractility in rats. In this study, we investigated possible stimulatory effect of apelin on myometrial contractility in calcium free condition.

Methods: 

Adult Wistar rats in dioestrus were decapitated and myometrium strips were removed (n=6). All strips were placed in a jacked tissue bath containing Krebs solution at 37 oC and pH 7.4, constantly bubbled with 95% oxygen and 5% carbon dioxide and were allowed to contract under 1g tension and isometric contractions were measured by force displacement transducer.

Results: 

After equlibration of spontaneous contractions, calcium free condition was set and contractions were disappeared immediately because of lack of extracellular calcium source. This silent period (no contraction) was recorded for 20 mins and apelin was added to the organ bath. Apelin was induced myometrial contraction at 10uM concentration in calcium free medium.

Conclusions: 

According to the results of this study and our previous data, apelin can stimulate uterus contractions by inducing calcium release from intracellular storages. Further detailed investigations are needed to clarify the mechanism(s) of apelin induction on myometrium contractility and the role of apelin in pregnancy and parturition processes.