Choledochosphincter inhibitory reflex: identification of the reflex in dogs and its significance

Reduced myoelectric activity in the sphincter of Oddi in a new model of chronic cholangitis in rabbits: an in vivo and in vitro study

BACKGROUND

Chronic cholangitis caused by hepatolithiasis is a common disease in Southeast Asia. Few studies have addressed the effects of chronic cholangitis on cyclic activity of the sphincter of Oddi (SO). In this study, we investigated the changes of myoelectric activity in rabbits with chronic cholangitis in vivo and in vitro.

METHODS

Chronic cholangitis was induced in rabbits by initially introducing three pieces of 2-0 silk suture and sequentially injecting E. coli into the choledochus through the tube in ductus cysticus. In in vivo experiments, myoelectric activity of SO was recorded by a circular electrode through the jejunum stump in conscious animals. In in vitro experiments, the SO was completely isolated and the myoelectric activity was recorded by a circular electrode in a 10-mL organ bath filled with Krebs solution, with or without addition of cholecystokinin-8 (CCK-8), KCl, ionomycin or induction of capacitative calcium entry (CCE).

KEY RESULTS

In comparison with control and non-infected rabbits, the rabbits with chronic cholangitis showed higher levels of alkaline phosphatase and gamma-glutamyltransferase and significant pathological changes including increased inflammatory infiltration and collagen deposition in mucosae or muscular layer. Cyclic myoelectric activity of SO at phases 2 and 3 of migrating motor complex and the excitatory response to CCK-8 were dramatically decreased in animals with chronic cholangitis. Myoelectric activity of SO was also significantly decreased in vitro with or without agonists or with induction of CCE.

CONCLUSIONS & INFERENCES

Myoelectric activity of SO and its response to agonists are decreased in rabbits with chronic cholangitis both in vivo and in vitro.

Manometric and radiographic evaluation of transduodenal sphincteroplasty (papillary dilation) in dogs

PURPOSE: To evaluate, in dogs, the functions of biliary sphincter subjected to dilation hydrostatic balloon by the point of view of the radiographic and manometric alterations. METHODS: Twenty dogs were submitted to laparotomy, duodenotomy, and enlargement of the major duodenal papilla- GA(n=10) - with balloon of 8mm inflated with pressure of 0,5atm, during 2 minutes or to the sham procedure - GB(n=10). The computadorized manometry and the cholangiography were done before and immediately after the initial procedure, one and four weeks after the dilation or the sham. It was calculated from the radiographic images: the mean, standard deviation, absolute and percentual variation of the diameter measures of the papilla. It was measured: the basal pressure in the papilla region, the contraction amplitudes and the choledoc pressure in all observation times (t0, t7 and t28). RESULTS: There was not differences in the diameter measures of the papilla in t0 (GA=5,14 +/- 1,1) (GB=4,64 +/-0,9), as well as in the absolute (0,14 mm) or relative (-2,7%) variations. In the animals of GA the papilla basal pressure measure was found to be smaller in t28 (11,1) than in t0 (18,6) and t7 (16,2). The contraction amplitudes measures were significantly smaller in the postoperatory times (post-t0, t7 and t28) when comparing to the initial time (pre-t0), in the animals of groups A and B. The average pressure values in the choledoc were also smaller in t28 (7,5) than in t0 (17,8) and t7 (12,6) in the animals of GA. CONCLUSION: the function of the major duodenal papilla is partially commited with the dilation, therefore it provoked the basal pressure decrease and compromising of the capacity of sphincter in its cyclical contractions up to the 28 days of observation.

Electrical activation of common bile duct nerves modulates sphincter of Oddi motility in the Australian possum

BACKGROUND

Sphincter of Oddi (SO) motility is regulated by extrinsic and intrinsic nerves. The existence of neural circuits between the SO and the proximal extrahepatic biliary tree has been reported, but they are poorly understood. Using electrical field stimulation (EFS), we determined if a neural circuit exists between the common bile duct (CBD) and the SO in anaesthetized Australian brush-tailed possums.

METHODS

The gallbladder, cystic duct or CBD were subjected to EFS with a stimulating electrode. Spontaneous SO phasic waves were measured by manometry.

RESULTS

EFS at sites on the distal CBD (12-20 mm proximal to the SO), but less commonly at more proximal CBD, evoked a variety of responses consisting of an excitatory and/or inhibitory phase. Bi-phasic responses consisting of an excitation followed by inhibition were the most common. Tri-phasic responses were also observed as well as excitation or inhibition only. These evoked responses were blocked by topical application of local anaesthetic to the distal CBD or transection of the CBD. EFS at sites on the gallbladder body, neck or cystic duct did not consistently evoke an SO response. Pretreatment with atropine or guanethidine reduced the magnitude of the evoked response by about 50% (p<0.05), pretreatment with hexamethonium had no consistent effect and pretreatment with a nitric oxide synthase inhibitor increased the response.

DISCUSSION

A neural circuit(s) between the SO and the distal CBD modulates SO motility. Damage to this area of the CBD during bile duct exploration surgery could adversely affect SO motility.