In vivo studies of the motility of the isthmic segment in the perfused rabbit oviduct.

The motility of the isthmic segment of the rabbit oviduct was studied in vivo using a perfusion model. The transisthmic flow of saline (38 degrees) was recorded at constant inflow pressures uni- or bilaterally. In untreated control animals there was a high resistance to flow within the isthmic segment. 12, 24, 48 and 72 h after induced ovulation by i.v. injection of human choriongonadotropin (HCG; 50 IU) the resistance gradually declined. No synchronous spontaneous motility pattern was recorded from the oviducts of any animal. When adrenergic agonists were administered 48 h after HCG, either intraluminally or intravenously, flow ceased after the alpha-adrenoceptor agonists noradrenaline (2-50 micrometers) or phenylephrine (2-10 micrograms), while an increased flow was recorded after the beta-adrenoceptor agonist isoprenaline (5-100 micrograms). The duration of the motor effects varied dose-dependently. Therefore it seems as if the motility of the isthmic segment is under adrenergic control, at least 48 h after HCG, with contractions caused by alpha-adrenoceptor stimulation and dilations caused by beta-adrenoceptor stimulation. The perfusion model used appears to be suitable for studying the adrenergic control of the isthmic segment after appropriate pretreatment with HCG.