Ethanol Inhibits Sphincter of Oddi Motility

Patients with alcohol-induced liver disease are at increased risk for pigment gallstones, which are known to be particularly associated with biliary stasis. Although the effects of ethanol on the sphincter of Oddi are thought to contribute to alcoholic pancreatitis, the precise effects of ethanol on the biliary component of the sphincter of Oddi are unclear. In the prairie dog the common bile and pancreatic ducts enter the duodenum separately, facilitating pressure measurement in the sphincter choledochus in isolation. We therefore used this model to test the hypothesis that ethanol administration alters sphincter of Oddi motility. Twenty-six male prairie dogs fed a nonlithogenic diet were studied. With the animals under α-chloralose anesthesia, a side-hole pressure-monitored perfusion catheter was positioned in the sphincter of Oddi and femoral arterial and venous catheters were placed. Sphincter of Oddi phasic wave frequency (F), amplitude (A), and motility index (MI = F × A) and arterial blood pressure were monitored at 10-minute intervals before (baseline), during 20-minute intravenous infusions of 15 mg/kg (n = 9), 150 mg/kg (n = 10), and 1.5 g/kg (n = 7) ethanol and for 20 minutes after ethanol infusion. The 15 mg/kg dose of ethanol had no effect, the 150 mg/kg dose tended to reduce sphincter of Oddi motility, and significant reductions in sphincter of Oddi amplitude and motility index were seen at the 1.5 g/kg dose. These data demonstrate that ethanol infusion inhibits both sphincter of Oddi amplitude and motility index and that this effect persists for at least 20 minutes following ethanol infusion. Ethanol may contribute to gallstone formation by altering biliary sphincter motility.