Effect of alcohol on cyclical myoelectric activity of the opossum sphincter of Oddi

Abstract

Ethyl alcohol may adversely affect pancreatic function by perturbing sphincter of Oddi (SO) or duodenal motor activity. The aim of this study was to identify the effect of ingested alcohol on the SO, duodenal, and gastric myoelectric activity in conscious opossums. In five adult opossums bipolar stranded stainless-steel wire electrodes were implanted on the SO, gastric antrum, and duodenum. After a 2-week recovery period, each animal underwent eight 8-hr recording sesions while fasted and awake. After two fasting cycles of the migrating myoelectric complex, animals were randomly fed either 10 ml of a 30% ethyl alcohol solution or 10 ml of water via an esophageal tube, and recordings continued for 4–6 hr. During the control state, cyclical myoelectric spike activity was recorded from the SO, gastric antrum, and duodenum with a mean ± SD cycle length of 73.5 ± 15.0 min, 74.3 ± 10.1 min, and 94.8 ± 8.7 min, respectively. With alcohol, SO and duodenal cycle lengths were unchanged while gastric cycle length decreased. However, alcohol effected a significant increase in peak SO spike burst frequency with no corresponding change in gastric or duodenal spike burst frequency. An equivalent volume of water had no influence on sphincter of Oddi myoelectric activity. It is concluded that ingested alcohol induces increased myoelectric activity from the opossum SO, independent of changes in activity of the duodenum or stomach. Since the SO plays a major role in metering bile and pancreatic flow into the duodenum, this may be a factor in alcohol-induced pancreatitis.