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

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Abstract
The motility of the isthmic segment of the rabbit oviduct was studied in vivo using a perfusion model. The transisthmic flow of saline (38.degree.) was recorded at constant inflow pressures unilaterally or bilaterally. In untreated control animals there was a high resistance to flow within the isthmic segment. At 12, 24, 48 and 72 h after induced ovulation by i.v. injection of human chorionic gonadotropin [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 i.v., flow ceased after the .alpha.-adrenoceptor agonists noradrenaline (norepinephrine; 2-50 .mu.g) or phenylephrine (2-10 .mu.g), while an increased flow was recorded after the .beta.-adrenoceptor agonist isoprenaline (5-100 .mu.g). The duration of the motor effects varied dose dependently. 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.