Graded effect of protein on regional myoelectric activity of the opossum sphincter of Oddi.
Academic Article
Overview
abstract
Although it is known that the sphincter of Oddi exhibits a myoelectric response to intraluminal nutrients, the effect of specific dietary components has not been well characterized. The aim of this study was to determine the effect of intragastric instillation of a protein meal on regional myoelectric activity of the opossum sphincter of Oddi. Seven adult opossums were chronically prepared with self-retaining bipolar electrodes secured to the proximal and distal parts of the sphincter. After a 2-week recovery period, and with the animals fasted and conscious, myoelectric activity was recorded for two cycles of the migrating myoelectric complex. The animals then received graded calories of protein through an orogastric tube and recordings were continued until return of the fasted cyclic activity. Doses of 60, 120, and 240 kcal of protein elicited increases in myoelectric spike activity of the proximal sphincter of 18.7%, 41.9%, and 66.6%, respectively. Similarly, the length of the fed state was prolonged by increasing caloric loads, with mean (plus or minus standard error of the mean) times of 266 +/- 25, 292 +/- 15, and 375 +/- 42 minutes for each dose. A similar relationship was noted in the distal part of the sphincter. Regression analysis between the proximal and distal parts of the sphincter during the fasted and fed states showed a strong and persistent correlation of gradient of spikeburst frequency. We conclude that myoelectric spike frequency of the opossum sphincter of Oddi exhibits a dose-related response to intragastric protein calories. Furthermore, the proximal and distal parts of the sphincter remain electrically coupled, with the proximal region pacing the distal region during the fasted state and after protein administration.
