Obstructive jaundice in rats results in exaggerated hepatic production of tumor necrosis factor-alpha and systemic and tissue tumor necrosis factor-alpha levels after endotoxin

BACKGROUND

Obstructive jaundice (OJ) predisposes patients to postoperative sepsis. We determined whether OJ led to an increased endotoxin stimulated tumor necrosis factor-alpha (TNF-alpha) production by macrophage-rich organs and whether a lack of intraluminal gut bile contributed to this increased sensitivity.

METHODS

Rats underwent laparotomy and common bile duct ligation and division (CBDL) or sham operation after they were given low-dose endotoxin or saline solution (NS). TNF-alpha levels in plasma, perfusate from the isolated perfused rat liver, and tissue from lung, spleen, and liver were measured 90 minutes later. An additional group underwent creation of a choledochal-vesical fistula and endotoxin administration.

RESULTS

The plasma TNF-alpha, liver perfusate TNF-alpha, and the tissue TNF-alpha levels in liver, lung, and spleen were significantly elevated in the CBDL + endotoxin (CBDL + ETX) group compared with the SHAM + ETX and CBDL + NS groups (p < 0.05). The choledochal-vesical fistula group after endotoxin had plasma TNF-alpha levels only 27% that of the CBDL + ETX group (p < 0.05).

CONCLUSIONS

OJ sensitizes macrophage-rich organs to produce larger amounts of TNF-alpha in response to endotoxin. This sensitization is not solely due to decreased intraluminal gut bile.

Effect of cholestasis on regulation of cAMP synthesis by glucagon and bile acids in isolated hepatocytes

Previously, we have reported that bile acids can directly inhibit hormone-induced adenosine 3',5'-cyclic monophosphate (cAMP) formation through a protein kinase C (PKC)-dependent mechanism [Bouscarel, B., T.W. Gettys, H. Fromm, and H. Dubner. Am. J. Physiol. 268 (Gastrointest. Liver Physiol. 31): G300-G310, 1995]. Therefore, the regulation of cAMP synthesis by glucagon and bile acids was investigated in hepatocytes isolated after 2-day ligation of the common bile duct in Golden Syrian hamsters. The bile acid concentration was increased 30-fold in the serum, whereas it was not significantly different in the bile of duct-ligated vs. sham-operated hamsters. The glycine/taurine and cholate/chenodeoxycholate ratios were significantly increased fourfold and sevenfold, respectively, only in the serum of bile duct-ligated hamsters. Ligation of the bile duct decreased the efficacy of glucagon-stimulated cAMP synthesis by 40-50% without changing its potency. This attenuation of cAMP synthesis, which was also observed with forskolin, remained in the absence of any detectable amount of bile acids in the hepatocytes. The decrease in glucagon-stimulated cAMP production was also not attributable to changes in either the affinity or the number of receptors for this hormone. The potency and efficacy of the bile acids to inhibit glucagon-induced cAMP formation was also reduced in bile duct-ligated hamsters. The inhibitory regulation of cAMP synthesis through angiotensin II was similarly diminished after bile duct ligation. Although the total expression of PKC-alpha was not affected, an increased translocation by 60% from the cytosol to the membrane fraction was observed in hepatocytes isolated after bile duct ligation. Therefore, during cholestasis and prolonged exposure of the liver to bile acids, both the stimulatory and inhibitory regulatory, mechanisms of cAMP synthesis are compromised in an irreversible manner because the effects persist even after isolation of the hepatocytes. This decreased regulation of cAMP synthesis is possibly mediated through PKC-alpha activation.

Comparison of bile duct pressures following sphincterotomy and endobiliary stenting in a canine model

BACKGROUND

Cystic duct (CD) leaks following laparoscopic cholecystectomy may be diagnosed and managed with ERCP. Treatment options include endoscopic sphincterotomy (ES) and/or endobiliary stenting (Stent). This study was undertaken to determine if ES or Stent is more effective in lowering bile duct pressures by disrupting the pressure gradient created by the sphincter of Oddi and therefore more beneficial in the management of CD.

METHODS

Mongrel dogs underwent midline laparotomy and antegrade cannulation of the common bile duct (CBD) with an umbilical artery catheter. Baseline CBD pressures were measured following duodenotomy; 5 Fr and 7 Fr stents measuring 2.5 cm, 4.5 cm, and 7 cm were inserted retrograde into the CBD. CBD pressure was measured after each stent insertion. A 1-cm sphincterotomy was the performed using a double channel papillotome.

RESULTS

Insertion of both 5 Fr and 7 Fr stents significantly lowered CBD pressure as compared to sphincterotomy alone, p < 0.05. There was no significant difference in the reduction in CBD pressure following the insertion of either the 5 Fr or 7 Fr stents of varying lengths. Sphincterotomy alone did not significantly decrease CBD pressure as compared to baseline pressure. The insertion of a stent following sphincterotomy also caused a significant decrease in CBD pressure as compared to sphincterotomy alone, p = 0.034.

CONCLUSION

Stent placement or ES with Stent placement significantly reduced CBD pressure as compared to ES alone. Stent diameter and length were not significant variables in this study. These results support the use of Stent or ES with Stent rather than ES alone in the management of CD leaks.

[Interaction of octapeptide of cholecystokinin, vasoactive intestinal peptide and substance P on dynamics of biliary system and cardiovascular system]

We tested in vivo: (a) the effect of an i.v. infusion of cholecystokinin octapeptide, vasoactive intestinal peptide or substance P on dynamics of biliary system and cardiovascular system, (b) the relation of dynamics of biliary system and cardiovascular system. In 91 anesthetized guinea pigs, left ventricle motility of heart, sphincter of Oddi motility and common bile duct pressure were monitored during the intravenous administration of cholecystokinin octapeptide (CCK-OP), vasoactive intestinal peptide (VIP), substance P (SP) and combination of CCK-OP and VIP. Intravenous CCK-OP increased fasting Oddis sphincter motility index, decreased the basal pressure in sphincter of Oddi, increased common bile duct pressure, and decreased the left ventricle of heart motility. VIP alone showed no significant effect on biliary system and cardiovascular system, but in conjunction with CCK-OP it produced inhibition on the effects of CCK-OP on both sides. Exogenous SP acted like CCK-OP on both biliary system and cardiovascular system, but it was less potent. We conclude that it may be an important interaction between dynamics of biliary system and cardiovascular system; and gastrointestinal peptide plays an important role in this interaction in guinea pigs.

Nephrotoxicity of acetaminophen in male Wistar rats: role of hepatically derived metabolites

The role of hepatically derived metabolites was studied in rats treated with a nephrotoxic dose of acetaminophen (APAP, 1000 mg/kg b.wt. i.p.). Hepatic glutathione (GSH) content 16 h after APAP dosing was significantly decreased (control = 3.83 +/- 0.1, APAP = 2.51 +/- 0.3 mumol/g wet tissue), whereas renal GSH levels were not changed. The role of hepatically derived GSH conjugates was investigated by administering the gamma-glutamyl-transpeptidase inhibitor, acivicin (20 mg/kg b.wt. i.p.). Treatment with acivicin led to a significant decrease in hepatic and renal gamma-glutamyltranspeptidase activity. Administration of acivicin 1 h before APAP administration protected against the alterations of glomerular filtration rate and urea and creatinine plasma levels induced by APAP. The appearance of epithelial cells and granular casts as well as the urinary excretion of protein and glucose were decreased compared with rats not pretreated with acivicin. Hepatocellular damage (evaluated by glutamic pyruvic transaminase levels) induced by APAP was not altered by acivicin pretreatment. APAP plasma levels and its urinary excretion were the same whether the rats were pretreated with acivicin or not. A group of rats was fitted with an exteriorized biliary cannula before APAP administration to study the contribution of the biliary excretion route of APAP metabolites in the APAP-induced renal damage. No differences were observed on APAP-induced renal effects between rats cannulated or not. Our results suggest that hepatically derived APAP metabolites are partially responsible for APAP renal effects. The sinusoidal efflux of these metabolites is also suggested.

Altered hepatic localization and expression of occludin after common bile duct ligation

Epithelial tight junctions form a regulated barrier that seals the paracellular space and prevents mixing of luminal contents with the interstitium. This barrier is composed of a group of proteins including the putative "sealing" protein occludin that appears to bind directly to a cytoplasmic junction protein, ZO-1. To study the interaction and regulation of these two components when paracellular integrity is altered, we assessed protein expression and immunofluorescent (IF) localization of ZO-1 and occludin in a rat model of hepatocyte tight junction damage induced by common bile duct ligation (CBDL). Protein levels were detected in liver by immunoblotting and IF localization by 3-dimensional reconstruction of serial 0.5-micron confocal microscopic optical sections. As previously described, ZO-1 protein levels progressively increased to threefold control levels 9 days after CBDL. In contrast, occludin protein levels decreased by 50% within 2 days after CBDL and returned to control values by 9 days. In control IF sections, ZO-1 and occludin colocalized, forming thin continuous staining outlining canaliculi. After CBDL, ZO-1 staining appeared discontinuous, and a punctate pericanalicular accumulation of signal developed around junctional areas. Occludin staining was also discontinuous after CBDL, but, in contrast to ZO-1, was not punctate and remained localized either in a linear fashion along canalicular margins or in a homogeneous fashion in immediately surrounding areas. CBDL results in changes in the expression and localization of the putative tight junction sealing protein occludin in hepatocytes that are distinct from those observed for the peripheral membrane tight junction protein ZO-1.(ABSTRACT TRUNCATED AT 250 WORDS)

Does hyperamylasemia in choledochal cyst indicate true pancreatitis? An experimental study

Patients with choledochal cyst often have repeated attacks of abdominal pain accompanied by hyperamylasemia, and they may be diagnosed as having acute pancreatitis. However, the attacks generally tend to subside in a short period by conservative treatment, and evidence of pancreatitis is rarely observed at the time of surgery. Choledochal cyst is commonly associated with pancreatobiliary maljunction, and high concentrations of pancreatic enzymes in bile are usually observed. When the bile duct pressure increases due to obstructive cholangitis, pancreatic enzymes in bile may regurgitate into the blood stream. Cholangiovenous reflux of amylase might cause hyperamylasemia. In order to investigate the mechanism of hyperamylasemia by cholangiovenous reflux, canine pancreatic juice or bile from a patient with choledochal cyst was injected into the obstructed common bile duct in dogs. The pancreatic enzymes in bile could readily enter into the blood stream at the pressure level of 15 mmHg or more in the bile duct. The peak amylase level in the thoracic lymph was observed to be more than 4 times higher than that in the blood serum, and the lymph flow during 30 minutes increased significantly from 8.1 to 20.4 ml at the bile duct pressure level of 20 mmHg. The reflux of amylase in bile into the blood stream via both the hepatic vein and thoracic duct might result in hyperamylasemia in the patients with choledochal cyst.

Absorption of triglycerides with defined or random structure by rats with biliary and pancreatic diversion

Fat absorption may be compromised by pancreatic or bile insufficiency, resulting in low uptake of essential fatty acid and energy. Using a rat model of malabsorption, we examined the absorption of defined triglycerides with medium-chain fatty acids (MCFA) in the sn-1,3 positions and essential fatty acids in the sn-2 position (MLM) compared to other fats. The thoracic duct was cannulated for collection of lymph, and the common bile and pancreatic duct was cannulated to divert both the pancreatic juice and bile. The rats were given a single bolus of triglyceride as a taurocholate emulsion. Fat absorption was measured from collected lymph samples. The triglycerides administered were a defined triglyceride, MLM [mainly (8:0/10:0)-(18:2n-6)-(8:0/10:0)], a similar triglyceride subjected to chemical randomization, a mixture of medium-chain triglycerides and soybean oil, and soybean oil, respectively. The first three triglycerides had approximately 36 wt% linoleic acid (18:2n-6) content. Administration of defined triglyceride was followed by significantly higher lymphatic level (wt%) of 18:2n-6 (P < 0.01) as well as a relative enhancement in mol% of 18:2n-6 (P < 0.05) compared to the other triglycerides. Lymphatic absorption of MCFA was similar in the three first groups but not as efficient as for long-chain fatty acids. Our results indicate that defined triglycerides thus may provide a means to increase absorption of essential fatty acids in fat malabsorption, such as that seen in cystic fibrosis, or for pre-term infants.

Bile and pancreatic juice replacement ameliorates early ligation-induced acute pancreatitis in rats

BACKGROUND

In healthy rats, combined bile and pancreatic juice diversion from gut has a synergistic rather than additive effect on stimulation of exocrine pancreatic protein secretion. We hypothesized that exclusion of combined bile and pancreatic juice from gut exacerbates bile and pancreatic-duct ligation-induced acute pancreatitis in rats to a greater extent than exclusion of either bile or pancreatic juice alone.

METHODS

Bile and pancreatic juice (obtained fresh from donor rats) were replaced, separately or together, via a duodenal fistula beginning immediately before 6 hours of duct ligation. Pancreatic morphologic changes were evaluated with an acute pancreatitis histology score and morphometric quantitation of acinar-cell necrosis. Plasma amylase and cholecystokinin concentrations and pancreatic subcellular distribution of cathepsin B activity were determined. Characteristics of bile and pancreatic juice obtained from donor rats were also studied.

RESULTS

Combined bile and pancreatic juice replacement limited the increase in acute pancreatitis histology score by 77%, acinar cell necrosis by 95%, hyperamylasemia by 77%, and hypercholecystokininemia by 99%, while preventing subcellular redistribution of cathepsin B. Amelioration of pancreatic morphologic changes was significantly greater with combined bile and pancreatic juice replacement than with replacement of either bile or pancreatic juice alone.

CONCLUSION

In this experimental corollary of early gallstone-induced acute pancreatitis, combined bile and pancreatic juice exclusion from gut contributes to disease pathogenesis to a greater extent than exclusion of either bile or pancreatic juice alone.

Cholinergic nerve-mediated excitation in the guinea pig choledochoduodenal junction activated by distension

The electrical basis of propulsive contractions in the guinea pig choledochoduodenal junction (CDJ), which are triggered by distension, was investigated using intracellular microelectrode recording techniques. The isolated CDJ was placed in a continuously perfused tissue chamber at 37 degrees C. Membrane potential was recorded from smooth muscle cells in either the ampulla or in the upper CDJ (upper junction) regions, which were immobilized by pinning. Distension of the upper junction (20-30 s) by increasing intraductal hydrostatic pressure (mean elevation: 2.0 +/- 0.3 kPa, n = 13) triggered "transient depolarizations" (TDs: < 5 mV in amplitude and 2-5 s in duration) and action potentials in the circular muscle layer of the ampulla. The frequency of TDs in the ampulla was increased from 2.2 +/- 0.2 to 15.9 +/- 2.2 min-1 (n = 13) during distension. Simultaneous impalements of cells in the longitudinal and circular muscle layers in the ampulla revealed that subthreshold TDs in the circular layer were associated with an increased rate of action potential discharge in the longitudinal layer. Atropine (Atr; 1.4 x 10(-6) M) and tetrodotoxin (TTX; 3.1 x 10(-6) M blocked the distension-evoked increase in TD frequency, without affecting the frequency of ongoing TDs. The sulfated octapeptide of cholecystokinin (1-5 x 10(-8) M) increased the amplitude of TDs recorded in the circular muscle layer of the ampulla and increased action potential discharge rate. In separate recordings, radial stretch of the ampulla region increased the rate of discharge of action potentials in the smooth muscle of the upper junction.(ABSTRACT TRUNCATED AT 250 WORDS)

Respiratory variation of extrahepatic bile duct diameter during ultrasonography

The attachments and adjacent structures of the extrahepatic bile duct may not move uniformly throughout the respiratory cycle, potentially affecting the diameter of the common bile duct. This study was performed to evaluate possible respiratory variation in extrahepatic bile duct diameter. Thirty consecutive subjects with maximal anteroposterior common bile duct diameter of 5 mm or greater were studied. Inspiratory increase in ductal diameter exceeding 1 mm was noted in 11 subjects (37%), eight without biliary obstruction. Awareness of this normal phenomenon may avert sonographic misdiagnosis of common bile duct obstruction, particularly during fatty-meal sonography.

Biliary motility. Changes in detailed characteristics correlated to duodenal migrating motor complex and effects of morphine and motilin in dogs

The temporal relationship of biliary motility to the duodenal migrating motor complex and effects of morphine and motilin were studied in five dogs prepared with a duodenal cannula. Common bile duct, sphincter of Oddi, and duodenal manometry were performed awake. Sphincter of Oddi phasic contractions occurred even during the quiescent period of duodenal phase I and its activity increased from phase II to III. Minimum basal pressure of sphincter of Oddi and common bile duct pressure decreased from phase I to phase III. Both morphine and motilin induced premature phase III in the sphincter of Oddi and duodenum. Latencies of the effect were 0.2 min for morphine and 3.2 min for motilin (P < 0.01). After morphine, vigorous continuous contractions with high basal pressure occurred, being interrupted by brief and repeated inactive periods, similar to spontaneous phase III. Motilin-induced phase III appeared indistinguishable from spontaneous phase III. Although both agents induced phase III in the sphincter of Oddi, differences in the latency and contraction pattern suggest different mechanisms of action of these agents on the sphincter of Oddi.

[Manometric study of the biliary sphincter zone: a comparison between the length of phasic activity and the narrow distal segment]

Motor activity of the sphincter of Oddi has been evaluated in 26 patients who underwent ERCP examination. Manometric recordings from the common bile duct and the sphincter of Oddi were performed with a single end-lumen perfused catheter. The number of successive 3 mm spaced black marks, observed during the pull-through from the first appearance of the proximal sphincter activity to that of duodenal pressure, was used to measure the length of the sphincter zone. In 14 of 26 patients, the length of phasic activity zone of the sphincter of Oddi was 9 mm. However, the narrow distal segment of the common bile duct was 15.1 +/- 3.6 mm in length. In same patients, the length of phasic activity zone was shorter than the anatomical one. The mean sphincter of Oddi pressure (SOP) at the distance of 6 mm from the papillary pore (77.8 +/- 22.1 mmHg) was greater than that of 9 mm (58.4 +/- 27.0 mmHg) and 12 mm (51.0 +/- 16.9 mmHg). These results suggest that the location of the orifice of catheter should be taken into consideration when comparing the SOP.

Effect of ursodeoxycholic acid administration on bile duct proliferation and cholestasis in bile duct ligated rat

The origin, mechanism, and significance of the bile duct proliferation (BDP) associated with cholestasis remain unexplained. This study examined the effect of oral administration of ursodeoxycholic acid (UDCA) on both BDP and cholestasis in the rat. After bile duct ligation, male Sprague-Dawley rats were treated for 30 days with either UDCA (5 mg/day) (group A) or saline solution (group B). Animals were sacrificed at day 30. The serum activity of aminotransferase (ALT, AST), alkaline phosphatase, and gamma-glutamyltransferase (GGT) was significantly lower (P < 0.01) in the UDCA-treated rats. Total serum bilirubin and total serum bile acids were lower (P < 0.001) in group A. Moreover, the control of BA in bile was reduced also (P < 0.02). Conversely, serum cholesterol levels were not different between the two groups. Histological examination showed that the number of ductular cells in the portal areas was significantly (P < 0.001) reduced in UDCA-treated as compared to saline-treated rats. The replication activity, assessed as the number of bromodeoxyuridine-positive cells, was also significantly lower in treated animals (33 +/- 11 vs 64 +/- 22 per 1000 cells; P < 0.001). Lobular bile ductules were three times larger in group B, and extrahepatic duct measurements confirmed this increase in size of the larger biliary ducts (P < 0.001). These findings demonstrate that UDCA reduces BDP in response to BD ligation. Although the mechanism(s) of this effect is still hypothetical, UDCA may reduce the level of irritating bile salts such as chenodeoxycholic acid and lithocolate and increase periductular bile acid recirculation.(ABSTRACT TRUNCATED AT 250 WORDS)

The pharmacological reactivity of an isolated circular smooth muscle strip of the rabbit common bile duct

An in vitro isolated spiral strip of rabbit common bile duct was prepared and tested for its pharmacological reactivity. It was found to be a suitable preparation with a long lasting and stable sensitivity when exposed to various drugs. The pharmacological reactivity proved to vary along the common bile duct; the different portions (sphincteric, median and hepatic) displayed different activities to the various agonists and antagonists. The following receptors were identified in different sections: alpha and beta-adrenergic, muscarinic cholinergic, bradykinin, H1 and prostaglandin F2 alpha. Only the sphinteric portion exhibited rhythmic peristalsis; the other portions produced merely small, irregular spontaneous contractions.

Rat renal functions during the first days post-bile duct ligation

Renal functions during the early stage of hepatic damage before ascites formation were studied in adult female rats. Tubular and hemodynamic parameters were analyzed for 12 days after common bile duct ligation. The fractional excretion of water, sodium, and potassium increased from control values at every day studied. Glomerular filtration rate and renal plasma flow were found to be diminished on the fourth day. Renal plasma flow remained decreased while glomerular filtration rate was recovered on the sixth day after common bile duct ligation. Filtration fraction in both experimental groups (4 and 6 days) was higher than in control animals. These observations suggested a preferential efferent arteriole vasoconstriction that could be responsible for a blood flow redistribution to the medulla. This fact might cause the sodium diuresis with diminished urine-to-plasma osmolalities ratio. The onset of cortical vasoconstriction was confirmed by dopamine infusion to bile duct-ligated rats 4 days postsurgery. Hemodynamic and tubular parameters recovered to control values during dopamine administration. All the data point out diuresis and natriuresis as the earliest renal abnormalities in bile duct-ligated rats. This phenomenon could be associated not only to the cortical vasoconstriction proposed but also to another systemic modification associated to liver damage.

Biliary pressure variation in coordination with migrating motor complex of duodenum in patients with cholecystectomy and effects of morphine and cerulein

Pressures in the common bile duct and duodenum were continuously measured with two pressure microtransducers placed by endoscopy in 10 postcholecystectomy patients. A complete cycle of the migrating motor complex of the duodenum was obtained in seven patients, its length ranging from 62 to 174 min with a mean of 114 min. The biliary pressure showed a transient elevation of 5.0 +/- 0.6 (mean +/- SEM) mm Hg (P < 0.001) in concert with phase III of the duodenal cycle in all 10 patients, whereas it remained stable during other phases. Intramuscular morphine (0.2 mg/kg) given to induce spasm of the sphincter of Oddi 20 min after the passage of phase III invariably produced an activity front in the duodenum and a sustained increase in the biliary pressure, the magnitude of which was 8.3 +/- 0.9 mm Hg. The biliary pressure raised by morphine dropped after an intravenous injection of cerulein (0.1 microgram/kg) as a sphincter relaxant. These findings indicate that the biliary pressure rises transiently at phase III of the duodenal cycle in patients after cholecystectomy, probably due to contractions of the sphincter of Oddi.

[Intrabiliary pressure changes produced by inhalational anesthetics in dogs]

The common bile duct pressure was studied in dogs under inhalation of 1.0 MAC and 2.0 MAC of halothane, enflurane, isoflurane or sevoflurane. A double lumen catheter was inserted into the common bile duct through the cholecystic duct for the measurement of intraductal pressure in the choledochoduodenal junction. The intra-bile-ductal pressure (IBP) was measured with constant rate infusion methods every 10 minutes for one hour. After obtaining control IBP measurements, 44 dogs received randomly either 1.0 MAC (n = 6 in each group) or 2.0 MAC (n = 5 in each group) of each four inhalational anesthetics, through a non-rebreathing system. The decreases in IBP produced by 1.0 MAC concentrations of four inhalation anesthetics were not statistically significant although there was a decline from control measurements obtained for each group. The elevations of IBP following 2.0 MAC halothane, isoflurane or sevoflurane were significantly depressed and were 38.3 +/- 21.2, 67.5 +/- 23.8, 63.7 +/- 23.7 (%, mean +/- SD) of the control levels, respectively. However, 2.0 MAC enflurane produced no significant decrease in IBP.

The size and contractility of the gallbladder in infants

The size of the gallbladder and the common bile duct as well as the contractility of the gallbladder were measured in infants under the age of 1 year. A total of 43 healthy infants were studied at their routine visit to the well-baby clinic at the ages of 6 weeks, 4 months, 8 months or 12 months. Gallbladder size was measured before and after a test meal. Fasting gallbladder size increased with the age of the infants. However, when the size was corrected for the infant's weight, no age-related variation was found. The contraction index (CI) was determined as a percentage decrement of planimetric gallbladder size from the initial size. The mean CI declined with age from 75% (+/- 27%) (mean (+/- SD)) at the age of 6 weeks to 24% (+/- 28%) at the age of 12 months. Overall CI varied from -44% to 100%. An increase in gallbladder size after the test meal was observed in 4 infants. Gallbladder volumes were also calculated, but two-dimensional measurements were regarded as more accurate in infants. A large variation was found in the size as well as in the contractility of the gallbladder in infants less than 1 year of age.

Pentazocine reduces cholinergic responses in the guinea-pig extrahepatic biliary tract by a non-opiate mechanism

The mechanical responses of the guinea-pig gallbladder and common bile duct to pentazocine were measured in vitro. At concentrations of 1 microM or higher, pentazocine reduced the responses of the gallbladder and common bile duct to electrical stimulation and to carbachol. This antagonism was not blocked by naloxone and appears to be due to an atropine-like action of pentazocine. At concentrations of 5 microM or higher pentazocine induced gallbladder contraction which was naloxone-insensitive. Both effects were not affected by tetrodotoxin and appear to be due to direct action on the muscle. The antimuscarinic activity of pentazocine should be taken into consideration when this opioid is administered experimentally or clinically.

[Effects of high-dose fentanyl on intraductal pressure in the choledochoduodenal junction in dogs]

Changes in intraductal pressure in choledochoduodenal junction were studied following intravenous administration of fentanyl in dogs. The intraductal pressure was measured with constant-rate infusion method. A statistically significant increase in the intraductal pressure was demonstrated after the intravenous administration of fentanyl 5 micrograms.kg-1 and 75 micrograms.kg-1. The increase in intraductal pressure following fentanyl administration at a dose of 75 micrograms.kg-1 persisted for more than 5 hours. We conclude that in case of intravenous high-dose fentanyl administration special attention should be paid to spasm of choledochoduodenal sphincter.

Receptors mediating the contractile effect of serotonin (5-HT) in the isolated common bile duct of guinea-pig

The contractile effect of 5-HT in the isolated common bile ducts of guinea-pigs was studied. 5-HT, administered non-cumulatively, evoked contractions which were concentration-dependent. Responses due to the low concentrations of 5-HT were antagonised significantly by ketanserin (10(-7) M and 10(-6) M) and methysergide (10(-6)M and 10(-5) M) whereas those induced by the higher concentrations of 5-HT remained unchanged. Atropine (3 x 10(-8) and 10(-7) M) and ICS 205-930 (10(-7) M and 10(-6) in contrast inhibited the contractions elicited by high concentrations of 5-HT without altering significantly the responses due to the lower ones. The results led us to conclude that 5-HT evoked contractions at low concentrations are predominantly mediated by 5-HT2 receptors whereas those at high concentrations are dependent on acetylcholine release via the stimulation of 5-HT3 receptors.

Biomechanical study of the bile duct system outside the liver

Diseases of the bile duct system in the digestive system after surgery are common. In order to clarify the cause of these diseases, research on the diseases from a biomechanical perspective is increasing; however, the same cannot be said of biochemical research. In this paper, by using a new, well-devised testing apparatus, specimens extracted from the bile duct system of canine body are tested. The test data are analyzed using the finite deformation theory, and mechanical properties of the bile duct system outside the liver are investigated. The conclusions show that the viscoelasticity of the bile duct system is very small. In its normal physiological condition, the bile duct wall has an almost uniform distribution of circumferential and longitudinal stress. However, when the diseases of the bile duct system cause high pressure at the bile duct, the circumferential stress and longitudinal stress at the bile inside wall suddenly increase and are much larger than those stresses at the outside wall. The elastic modulus gradually becomes small from the common bile duct and the common hepatic duct to hepatic duct, and the value of elastic modulus for the cystic duct is almost equal to that of the hepatic duct.

Choledochoduodenal flow: effect of the sphincter of Oddi in opossums and cats

The aim of this study was to test in vivo (a) whether the sphincter of Oddi acts as a resistor or also as a pump, (b) the effect of an IV infusion of cholecystokinin (CCK) on choledochoduodenal flow, and (c) the ability of the choledochoduodenal junction to prevent duodenobiliary reflux in two animal species, opossums (n = 11) and cats (n = 8). Opossums were implanted with bipolar electrodes on the sphincter of Oddi and the adjacent duodenum. Cats were not. Experiments were performed in vivo using a propulsion evaluation system to test whether the Sphincter of Oddi was able to pump fluid from the bile duct to the duodenum against pressure gradients. In 5 opossums and 4 cats, choledochoduodenal flow was evaluated during the IV infusion of CCK (20 ng.kg-1.min-1). The opossum sphincter of Oddi moved fluid against duodenal pressure gradients of 6-45 cm H2O. The spike-burst frequency (6.4 +/- 1.7 min-1) was maximal at peak bile duct pressures and decreased as bile duct pressure decreased (4.9 +/- 1.6 min-1; P less than 0.001). Pressure pulses in the bile duct were observed at a frequency that correlated with sphincter of Oddi spike-burst frequency (r = 0.84; P less than 0.001). In cats, choledochoduodenal flow occurred only along a hydrostatic gradient; the sphincter of Oddi never acted as a pump but only as a resistor. Infusion of CCk significantly increased the frequency of sphincter of Oddi contractions in opossums, but the transfer of fluid from bile duct to duodenum was significantly reduced. In cats, the rate of fluid flow from the bile duct to the duodenum during CCK infusion did not differ from control values. Reflux of duodenal fluid into the biliary tree was never observed, even at duodenal pressures as high as 100 cm H2O. In conclusion, in vivo, the sphincter of Oddi is able to pump fluid from the bile duct to the duodenum against a pressure gradient in opossums, but, in cats, choledochoduodenal flow requires a bilioduodenal pressure gradient. The increase in sphincter of Oddi contraction frequency induced by CCK in opossums resulted in a decrease in active transsphincteric flow. Duodenobiliary reflux could not be elicited in opossums and cats under the conditions of these experiments.