CONTRACTILE CHARACTERISTICS OF FIMBRIAL, ISTHMIC, AMPULLAR, AND FIMBRIO-AMPULLAR SEGMENTS OF ISOLATED SOW (SUS-SCROFA) OVIDUCTS AS INFLUENCED BY OVULATION, ADRENERGIC-MECHANISMS, AND PROSTAGLANDIN-E

  • 1 January 1980
    • journal article
    • research article
    • Vol. 25  (1) , 28-35
Abstract
Spontaneous contractile characteristics, as well as inotropic influences of norepinephrine (NE) and prostaglandin(PG)E1 on different sow oviductal segments isolated from the preovulatory or early postovulatory period, were explored. Postovulatory fimbrial preparations contracted with higher intensity and slower frequency than preovulatory ones, while the spontaneous motility of other regions were comparable at both stages. NE depressed preovulatory ampullar and fimbrio-ampullar portions but stimulated fimbrial and isthmic segments. After ovulation NE enhanced the motility of all tubal regions, particularly the fimbrial ones. Phentolamine abolished and even reversed, on postovulatory ampulla, the contractile augmentation elicited by NE. PGE1 markedly diminished the tension and frequency of preovulatory fimbrial and fimbrio-ampullar segments, but it was inactive on other ampullar regions. This depressant influence on the preovulatory fimbrio-ampullar region was replaced, a few hours following ovulation, by a distinct contractile increment. Although phentolamine failed to alter the PGE1 postovulatory ampullar influences, it clearly blunted the PGE1 enhancement of postovulatory isthmic motility. Changes observed in adrenergic or prostaglandinic responses of the sow oviduct may be linked to influences exerted by rapid variations of circulating substances associated with the ovulatory process. It is also plausible that the action of PGE1 on the isthmus but not on the ampulla is indirect and attributable at least in part to the release of NE. The fimbrio-ampullar junction of the domestic sow apparently acts as a PG sphincter able to avoid the loss of oocytes newly introduced into the oviduct.