ESTROGEN INHIBITS SPHINCTER OF ODDI MOTILITY

Gallstones and sphincter of Oddi dysfunction are both more common in w omen than men, suggesting that endogenous hormones may play an importa nt role in these conditions. Female sex hormones are known to affect c holesterol metabolism and gallbladder motility. However, the effect of these hormones an the sphincter of Oddi has not previously been studi ed. We therefore tested the hypothesis that exogenous estrogen adminis tration would inhibit sphincter of Oddi motility. Twenty-three male pr airie dogs fed a nonlithogenic diet were studied. Under alpha-chloralo se anesthesia, a side hole pressure-monitored perfusion catheter was p ositioned in the sphincter of Oddi and perfused with degassed water at 0.15 ml/min. Femoral arterial and venous catheters were placed. Sphin cter of Oddi phasic wave frequency (F), amplitude (A), and motility in dex (MI = F X A), as well as arterial blood pressure (BP), were monito red for 10-min intervals before (control), during 20-min intravenous i nfusions of 0.1, 1, or 10 mu g/kg beta-estradiol, and for 20 min after estradiol infusion. Na response was observed at the 0.1- or 1-mu g do ses. Sphincter of Oddi motility was significantly (P < 0.05) reduced d uring estrogen infusion at the higher dose of 10 mu g, primarily due t o decreased phasic wave frequency. Sphincter motility remained depress ed for at least 20 min following estrogen infusion. We conclude that e strogen effects on the sphincter of Oddi may contribute to the higher incidence of gallstones and sphincter dysfunction seen in premenopausa l women. (C) 1994 Academic Press, Inc.