Intramural neural pathways between the duodenum and sphincter of Oddi in the Australian brush‐tailed possum in vivo.

Abstract

1. Balloon distension of the duodenum 2 cm oral or anal to the sphincter of Oddi-duodenal junction elevated the amplitude of spontaneous sphincter of Oddi phasic contractions by 37-7 + 8-5 or 120-1 + 79-8%, respectively (mean + S.E.M., both n= 6, P< 0 05, Wilcoxon test). To further investigate this response, this study aimed to determine if: (i) electrical field stimulation (EFS) of the duodenum influences sphincter of Oddi activity; (ii) intramural nerves mediate the response; and (iii) nicotinic and/or muscarinic receptors are involved. 2. Electrical field stimulation (70 V, 0 5 ms; 5-60 Hz, 10-20 s) of the duodenal anterior serosal surface 2-4 cm oral or anal to the sphincter of Oddi-duodenal junction, produced excitatory responses in the sphincter of Oddi in anaesthetized Australian brush-tailed possums (n = 45). 3. These responses were frequency dependent, maximal at 30 Hz (n = 4) and abolished by tetrodotoxin (9 jug kg-' I.A.; n = 6), or by crushing the duodenum (n = 3). Hexamethonium bromide (30 mg kg-' i.v.) did not significantly alter the response to duodenal EFS either oral (n =6) or anal (n =8) to the sphincter of Oddi-duodenal junction. Atropine sulphate (30 jug kg-' i.v.) reduced the response to duodenal EFS oral and anal to the sphincter of Oddi-duodenal junction to 11P2 + 5-8 (n = 6) and 45 0 + 26-8% (n = 8), respectively (both P< 0 05).4. Bilateral cervical vagotomy and guanethidine infusion (10 mg kg-' over 15 min i.v.) did not significantly alter the responses to duodenal EFS (n = 7). 5. Excitatory intramural neural pathways between the sphincter of Oddi and the segment of duodenum 4 cm oral and anal to the sphincter of Oddi-duodenal junction have been demonstrated. These postganglionic pathways may involve muscarinic receptors.

Distribution of nitric oxide synthase and vasoactive intestinal polypeptide immunoreactivity in the sphincter of Oddi and duodenum of the possum

“…The presence of anatomically identified neural connections between the SO and duodenum with immunoreactivity to both PGP9.5 and NOS confirms previous physiological studies that have shown a neurally mediated motor pathway between the SO and duodenum (Saccone et al 1994;Simula et al 1997). In the guinea-pig, neurons retrogradely labelled from the duodenum to the SO do not contain NOS immunoreactivity (Kennedy and Mawe 1998); a significant proportion of these neurons exhibit calbindin immunoreactivity and are Dogiel type II neurons.…”

“…Using electrical field stimulation (EFS) both in vivo and in vitro, we have provided evidence for intramural neural pathways between the SO and the duodenum in the possum (Saccone et al 1994;Simula et al 1997). Motor responses induced by the activation of these pathways by EFS are reduced, but not blocked, by hexamethonium suggesting the involvement of cholinergic pathways (Simula et al 1997).…”

Investigation of Relaxant Effects of Propofol on Sheep Sphincter of Oddi

“…These nerves, like hormones, are important in the control of SO motility and function [4,5] . Endoscopic retrograde cholangiopancreatography (ERCP) has evolved from a diagnostic tool into a primarily therapeutic procedure for a variety of biliary and pancreatic diseases [6,7] .…”

Regulation and responses of gallbladder muscle activity in health and disease

“…There is clearly a reciprocal interplay between the gallbladder and the sphincter of Oddi, as stimuli which cause gallbladder m uscle contraction lead to relaxation of the sphincter, and vice versa, and neural connections between the two, and between the gallbladder and the duodenum are known to exist. 42 Furthermore, inflammatory mediators such as bradykinin are known to have a direct action on smooth muscle in other sites, such as the intestine 43 and in the gallbladder in the guinea pig. 44 The remainder of this paper describes a number of in vitro studies we have performed to investigate these aspects of gallbladder muscle contraction.…”