Secretin induces variable inhibition of motility in different parts of the Australian possum sphincter of Oddi.

Al-Jiffry, B. O.; Jobling, J. M.; Schloithe, A. C.; Toouli, J.; Saccone, G. T. P.

The sphincter of Oddi (SO) may not function as a single structure. We aimed to determine the response of the proximal and distal segments of the bile duct (BD-SO) and pancreatic duct (PD-SO) components of the SO to secretin, with and without neural blockade with tetrodotoxin (TTX). In anaesthetized Australian possums, separate manometry catheters were placed in the proximal and distal BD-SO or PD-SO segments to record motility. Secretin, 50–1000 ng kg–1, was administered, followed by TTX, and re-administration of secretin, 500 and 1000 ng kg–1. Changes in the motility index (MI, frequency × mean amplitude) were determined. Statistical analysis utilized repeated-measures ANOVA. Secretin produced a dose-dependent decrease in MI from the proximal and distal BD-SO and PD-SO (all P < 0.001). The maximum inhibition, at 1000 ng kg–1, was 21 ± 4%, 33 ± 6% and 42 ± 5% of control (mean ± SEM), for proximal and distal BD-SO, and distal PD-SO, respectively. The proximal PD-SO MI, however, was inhibited to 62 ± 6% of control, at 1000 ng kg–1. TTX enhanced the secretin-induced response to the same level at the four sites (P < 0.02). We conclude that secretin inhibits the motility of the possum SO in a nonuniform manner and is modulated by neural activity.

SPHINCTER of Oddi; SECRETIN; BILE ducts; PANCREATIC duct; TETRODOTOXIN

Neurogastroenterology & Motility, 2001, Vol 13, Issue 5, p449

1350-1925

Academic Journal

10.1046/j.1365-2982.2001.00278.x