Effect of sensory denervation with capsaicin on liver fibrosis induced by common bile duct ligation in rat

Hepatic fibrosis represents an important stage in the progression of chronic liver disease to cirrhosis. In the present paper we have investigated whether capsaicin-sensitive neuropeptide-containing sensory neurons may participate in the development of liver fibrosis. The expression of hepatic fibrosis induced by common bile duct obstruction has been studied both in capsaicin- and vehicle-treated rats. Common bile duct-induced liver fibrosis was less marked in capsaicin-treated rats than in vehicle-treated rats. Diffuse alterations of liver parenchyma structure with marked collagen deposition and nodular regeneration occurred 8 weeks after common bile duct ligation in vehicle-treated animals, while none of the capsaicin-treated rats exhibited the formation of complete connective septa altering the parenchyma architecture. Both vehicle- and capsaicin-treated rats showed an increasing number of desmin-positive cells in the perivenular zone, but the density of these cells was lower in treated animals than in untreated rats. The hydroxyproline content of the liver increased after common bile duct ligation in a time-dependent manner. Eight weeks after bile duct obstruction vehicle-treated rats showed a 7-fold increase of liver collagen content in comparison to normal animals. This enhancement was about 3.5-fold in capsaicin-treated rats. These findings raise the possibility that the peripheral release of neuropeptides stored in sensory nerves might participate in the development of liver fibrosis following common bile duct obstruction.

[A model of experimental acute pancreatitis in the conscious rat]

We describe an experimental model of acute pancreatitis in conscious rats, based on biliary reflux; sodium deoxycholate was injected while maintaining the common duct (biliary and pancreatic) temporally occluded. A progressive increase of serum amylase, cardiac rate and hematocrit value, as well as a decrease of plasma proteins are characteristic of this experimental model. Blood pressure was maintained until shortly before death, which occurred after 85 minutes. This is a simple model, reliable and reproducible, which requires minimal surgical manipulation.

Functional and morphological relationships between the feline main pancreatic and bile duct sphincters

To analyze the relationships between the bile duct and main pancreatic duct sphincters, the resistance to flow through these sphincters was studied simultaneously with perfusion techniques in anesthetized cats. Basal flow resistance was higher in the pancreatic sphincter than in the bile duct sphincter. The pressure in one duct system was not affected by the flow in the other. The muscular activities in the sphincters were usually well coordinated. Distention of the upper biliary tract or the pancreatic duct system reduced the flow resistance in both sphincters. Cholecystokinin-8 (0.01 micrograms), duodenal distention, and sublingual glyceryl trinitrate (0.4 mg) also relaxed both sphincters, whereas secretin in a dose that induced pancreatic secretion had no consistent effect. Morphine increased flow resistance in both systems. These functional studies indicate that the 2 sphincters share smooth muscle fibers at the level where the flow resistances arise, and there are thus no grounds for separate control of the sphincters. There was no evidence of a functionally common sphincter ampulla. The conclusions drawn from the manometric results were supported by morphological findings in this study.

Alkaline phosphatase activity in hepatic tissue and serum correlates with amount and type of bile acid load

Bile acids stimulate synthesis of alkaline phosphatase (ALPase) in the liver. We studied how alterations in bile acid type and load affect ATPase activity in hepatic tissue and in the serum. We increased the load of natural bile acids in rats by bile duct obstruction (BDO) or by creating a shunt between the common bile duct and superior vena cava (choledocho-caval shunt or CCS). Concentration of bile acids and ALPase activity in hepatic tissue rose more rapidly in the BDO model than in CCS. ALPase activity on the hepatocellular surface, normally confined to the canaliculus, spread outward to involve basolateral membrane in livers with high total hepatic ALPase activity. When the bile acid pool was reduced by a 12-hour biliary drainage in the CCS model, surface distribution of ALPase reverted to a nearly normal pattern. We substituted the endogenous bile acid pool with an equimolar amount of the single bile acid, taurocholic (TCA), tauroursocholic, taurohyocholic, or tauroursodeoxycholic acid in the CCS. The first two bile acids have a 12 alpha-hydroxyl group, whereas the latter two do not. After 12 hours, hepatic ALPase activity was increased with TCA or tauroursocholic substitution, but not with taurohyocholic or tauroursodeoxycholic. Again, surface distribution of ALPase activity correlated with the tissue ALPase activity. However, the serum activity increased significantly only with TCA, the most detergent of the bile acids. In bile fistula rats only infusion of TCA accelerated biliary secretion of ALPase. The above results suggest that hepatic synthesis and serum activity of ALPase are influenced by two different features of bile acids: the former by structure (the 12 alpha-hydroxyl group) and the latter by a physical property (detergency).

Nerve-mediated contractile and electrical activity of the guinea-pig choledocho-duodenal junction

The intrinsic motor innervation of the guinea-pig choledocho-duodenal junction was investigated by recording the contractile and intracellular electrical activity of smooth muscle from different regions of this tissue. Electrical transmural nerve stimulation evoked phasic contractions in rings of muscle from the ampulla (0.45 s-1) and tonic contractions in rings of muscle from the choledochal sphincter. Intracellular microelectrode recordings from muscle strips from these two regions revealed that excitatory junction potentials (peak amplitude 7 mV) evoked by transmural nerve stimulation were more conspicuous in muscle strips from the choledochal sphincter, but inhibitory junction potentials (peak amplitude 13 mV) were of larger amplitude in muscle strips from the ampulla. Contractions and membrane depolarization evoked by transmural nerve stimulation were sensitive to 1.4 microM atropine and abolished by 3.1 microM tetrodotoxin. Histological studies on the choledocho-duodenal junction also revealed that the distribution of smooth muscle was non-uniform along the tissue. These results suggest that the two regions may have different functions in the motility of the choledocho-duodenal junction.

[Lipoprotein cholesterol in the blood plasma of rats with a bile circulation disorder]

The experiments were carried out on two groups of rats with obstruction or cannulation of bile duct. Plasma was obtained from the tail venous blood before and 24 hours after operation. The bile duct obstruction caused hypercholesterolemia and considerable increase in the cholesterol content of low-density and very low-density lipoprotein (cholesterol bound to LDL and VLDL). Cannulation of total bile duct slightly increased CH-LDL+VLDL. The change in concentration of high-density lipoprotein cholesterol was insignificant in both models of bile disturbance while index of atherogenesis increased.

Flow resistance in the feline choledocho-duodenal sphincter as studied by constant-pressure and constant-perfusion techniques

During interdigestive periods, there is a resistance to flow in the biliary tract exerted by the sphincter of Oddi, resulting in a pressure gradient between the common bile duct and the duodenum. In this experimental study, this flow resistance was studied with both a constant-flow and a constant-perfusion technique in fasted, anaesthetized cats. The flow resistance exerted by the sphincter is higher when it is perfused by a constant flow compared to when the common bile duct pressure is kept constant and the flow varies in response to its muscular activity. It was demonstrated with each method that the flow resistance in the choledocho-duodenal junction is reduced in response to distension of the biliary tree and gallbladder and also by distension of the duodenum. Cholecystokinin was shown to reduce the flow resistance in the choledocho-duodenal junction as estimated with either method.

Intravital microscopy: a new in vivo technique for visualizing and quantifying effects of regulatory peptides on choledochoduodenal junction motility

Using intravital microscopy, we studied the in vivo effects of regulatory peptides on choledochoduodenal junction motility in guinea pigs. During basal and hormone-stimulated periods, intravital microscopy documented rhythmic, asymmetrical, "milking" contractions of the sphincter ductus choledochi (SDC) which occurred independent of sphincter ampullae (SA) contractions or were followed by SA contractions. Cholecystokinin octapeptide (CCK-8) (greater than or equal to 0.01 micrograms/kg) increased the frequency of SDC contractions and at higher doses (greater than or equal to 0.1 microgram/kg) increased the frequency of SA contractions. Pentagastrin (greater than or equal to 1.0 microgram/kg) and secretin (10 micrograms/kg) decreased the contraction frequencies of both sphincters. Biliary manometry demonstrated similar effects of these peptides on the frequency of the SDC and SA contractions, but also showed that CCK-8 (0.1 microgram/kg) increased the amplitude of SDC and SA contractions while pentagastrin (1 microgram/kg) decreased the amplitude of only SDC contractions. Tetrodotoxin and atropine did not affect hormone-induced changes in frequency, but tetrodotoxin reduced the increase in amplitude of contraction caused by CCK-8. We concluded that intravital microscopy provides a sensitive, in vivo technique to visualize and quantify the complex motility of a small structure like the choledochoduodenal junction.

Functional gradients in muscle cells isolated from gallbladder, cystic duct, and common bile duct

The existence of a gradient inherent to muscle cells of the biliary tract was examined in muscle cells isolated separately from the fundus of the gallbladder, cystic duct, and common bile duct of the dog. Muscle cells, measured in suspension or as single perfused cells, exhibited a proximal-to-distal gradient expressed by the magnitude of response and the sensitivity to hormonal cholecystokinin octapeptide and neural (acetylcholine and methionine-enkephalin) contractile agonists. Measurements in suspensions showed that cells from the fundus 1) were 7-40 times more sensitive to contractile agonists than cells from the cystic duct and 13-200 times more sensitive than cells from the common bile duct and 2) generated greater maximal contraction. The latter was expressed by the ratio of maximal responses (fundus: cystic duct cells, 1.90 +/- 0.12, P less than 0.001; fundus: common bile duct cells, 1.50 +/- 0.07 P less than 0.001), which was independent of sensitivity to agonists. Similar results were obtained in measurements on single cells with respect to relative sensitivity and to ratio of maximal responses (fundus: cystic duct cells, 1.80 +/- 0.08, P less than 0.001; fundus: common bile duct cells, 1.49 +/- 0.06, P less than 0.001). The ratio of responses to low concentrations of agonists was even higher (three- to fourfold), reflecting both the greater sensitivity and the greater contraction of muscle cells of the fundus. We conclude that a proximal-to-distal biliary gradient exists that is an inherent property of muscle cells from various regions of the biliary tract; the gradient would act to facilitate gallbladder emptying in response to hormonal and neural stimulation.

The effect of (a) neomycin and lactulose treatment on systemic and portal serum GABA levels in rats and (b) pH changes on [3H] GABA binding to isolated rat hepatocytes

Recently it has been suggested that gamma-aminobutyric acid (GABA), a potent inhibitory neurotransmitter, may be involved in the pathogenesis of hepatic encephalopathy. If so, then therapeutic interventions that are known to improve or exacerbate the encephalopathic state should have significant effects on GABA homeostasis. In the present study, we determined the effect of neomycin and lactulose treatment on systemic and portal venous blood GABA levels in healthy rats and rats having undergone common bile duct ligation. We also studied the effect of alterations in extracellular pH on [3H]GABA binding to isolated rat hepatocytes. The results of the study revealed that systemic serum GABA levels in neomycin (0.38 +/- 0.09 mumoles/L: mean +/- SEM) and lactulose (0.45 +/- 0.11 mumoles/L) treated healthy rats were significantly lower than in healthy controls (0.63 +/- 0.21 mumoles/L, p less than 0.01 and 0.05 respectively). The same was true of portal venous GABA levels (1.02 +/- 0.29, 1.14 +/- 0.69 vs 3.44 +/- 1.6 mumoles/L respectively). In liver diseased rats however, systemic serum GABA levels in neomycin (2.35 +/- 0.22 mumoles/L) and lactulose (1.92 +/- 0.29 mumoles/L) treated rats were similar to those in untreated liver disease controls (2.36 +/- 0.22 mumoles/L) as were portal venous GABA levels (5.76 +/- 0.73, 2.91 +/- 0.46 vs. 3.82 +/- 0.47 mumoles/L respectively). [3H]GABA binding to isolated hepatocytes was significantly decreased (46%) in the presence of an alkaline extracellular environment. The results of this study indicate that, in healthy but not in liver diseased rats, peripheral GABA homeostasis is altered by agents or factors that are known to improve or exacerbate the encephalopathic state in humans.

Effects of cholecystokinin octapeptide on contractile motility of guinea pig common bile duct

Cholecystokinin octapeptide (CCK-8)-induced contraction and [3H]acetylcholine ([3H]-ACh) release from the longitudinal muscle strip of the guinea pig common bile duct were studied by a standard organ bath method and superfusion system. CCK-8 (10(-7) M) caused a biphasic contraction, a rapid phasic contraction followed by a fading tonic contraction. Hexamethonium, propranolol, and phentolamine had no effects on CCK-8-evoked contraction. Atropine or tetrodotoxin significantly reduced CCK-8-evoked initial phasic contraction and produced a rightward shift of the dose-response curve for CCK-8 (10(-10)-3 x 10(-7) M). CCK-8 provoked a significant [3H]ACh release in a dose-dependent manner, which was almost completely abolished by tetrodotoxin or Ca2+-free medium. These results suggest that CCK-8 receptors are present not only on the smooth muscle cells but also on the intramural cholinergic nerve cell bodies of the guinea pig common bile duct.

The effect of nalbuphine on the common bile duct pressure

The effect of Nalbuphine on the common bile duct pressure of ten women who had cholecystectomy and common duct exploration for cholelithiasis and choledocholithiasis was studied. In this pilot study, intravenously inject Nalbuphine (20 mg) significantly raised the common duct pressure (P less than 0.01). However, none of the patients experienced pain as a result of the elevation in the biliary pressure; there was no deleterious cardiopulmonary effect.

Gastroduodenal regulation of common duct bile flow in the dog

We investigated the relationship between the entry of individual drops of bile into the duodenum and gastroduodenal motor activity in the fasted state in 10 conscious dogs. The common bile duct was transected and a catheter was inserted through each end. The exteriorized catheters were connected to a photometric drop-flow meter. During phase III activity, bile entered the duodenum in single drops, only in between two consecutive contractions, or as a series of drops during transient inhibition of duodenal contractions by antral phase III contractions. During phase II activity bile also entered the duodenum, usually in between contractions or when the duodenum was intermittently quiescent. Bile entered the duodenum during a duodenal contraction only when the contraction amplitude was less than 15% +/- 1% (mean +/- SE) of the maximal amplitude during phase III contractions. Bile flow into the duodenum showed a cyclic pattern with a peak during late duodenal phase II activity and a trough during duodenal phase I activity only when phase III activity originated in the duodenum and migrated caudad. There was no cyclic pattern of bile flow when phase III activity originated in the proximal jejunum and migrated caudad. The total volume of bile flow in a migrating motor complex cycle and bile flow rate were greater when phase III activity started in the proximal jejunum than when it started in the duodenum. We conclude that gastroduodenal contractions play an important role in the regulation of bile flow into the duodenum. The cyclic pattern of bile flow is altered when phase III activity starts ectopically in the jejunum.

Optimal irrigation pressures in operative choledochoscopy

A prospective study was conducted on 20 consecutive patients who underwent elective exploration of common bile-ducts for stones to determine the optimal irrigation pressures in choledochoscopy. Ten patients had rigid choledochoscopy and 10 patients had flexible choledochoscopy. Choledochoscopic views were assessed at low irrigation pressure (irrigant delivered at hydrostatic pressure of 1 m of water or 80 mmHg) and high irrigation pressure (irrigant delivered at cuff pressure of 300 mmHg plus hydrostatic pressure of 80 mmHg). Choledochoscopic views were better with high than low irrigation pressures for rigid choledochoscopy. However, there was little difference in the views for flexible choledochoscopy. Common bile-duct pressures were measured with irrigant delivered at pressures 80-380 mmHg at intervals of 50 mmHg. With increasing irrigation pressures, the common duct pressures rose and they were consistently higher in flexible than rigid choledochoscopy. The common duct pressures in rigid choledochoscopy never exceeded the recommended safety limit, even at the high irrigation pressure of 380 mmHg. With flexible choledochoscopy, the common duct pressure was below the recommended safety limit only with low irrigation pressure of 80 mmHg. Therefore, it is recommended that a high irrigation pressure of 380 mmHg for rigid choledochoscopy and a low irrigation pressure of 80 mmHg for flexible choledochoscopy be used.

Relation between renal and hepatic excretion of drugs: VII. Hepatic and renal excretion of phenol red in thioacetamide-induced acute and chronic liver damage

Acute and chronic liver damage was induced in rats by thioacetamide (TAA). Centrilobular liver cell damage associated with an accumulation of lipid droplets was produced by a single high dose (10 mg TAA/100 g b.m.). Liver fibrosis, micronodular and macronodular liver cirrhosis were induced by chronic TAA treatment (300 ml/l drinking water for 1.5, 3 or 6 months). Acute administration of TAA caused a significant decrease of hepatic phenol red excretion but no compensatory increase of its urinary excretion. In contrast, 24 h after bile duct ligation renal excretion of the dye increased by about 50%. After chronic exposure to TAA for three months hepatic phenol red excretion remained reduced and renal excretion raised significantly. This compensatory increase of urinary excreted phenol red amounts did not occur after 6 months of TAA treatment, probably as a result of additional nephrotoxicity of TAA. Two weeks after cessation of TAA exposure for 3 months, hepatic and renal phenol red excretion returned to normal. Bile flow per animal increased significantly after 3 months of TAA exposure. Apparently this is due to a reduced intrahepatic reabsorption of canalicular bile in TAA-damaged liver.

Periodic gallbladder contraction maintains bile acid circulation during the fasting period: a canine study

Using a canine model we have studied the relationship between the interdigestive cycle in the small intestine, motility changes in the biliary tract and bile acid output into the duodenum from direct hepatic secretion and gallbladder emptying. Under anaesthesia catheters were inserted into the gallbladder, common bile duct and duodenum, and electrodes were attached to the small intestine in five dogs. These animals were subsequently studied conscious and fasting. A double marker technique was used to measure bile acid output from the gallbladder and liver while pressure in the gallbladder and common bile duct and electrical activity in the small intestine were monitored. Four complete interdigestive cycles were recorded in each dog. Output of bile acids from the gallbladder fluctuated with the phases of the cycle: being lowest in phase I (3.9 +/- 0.7 mumol/min); increasing significantly (P less than 0.005) in phase II (9.8 +/- 1.0 mumol/min); remaining elevated in phase III (13.9 +/- 1.7 mumol/min); and falling significantly (P less than 0.05) in phase IV (8.4 +/- 1.8 mumol/min). In contrast, hepatic secretion of bile acids directly into the duodenum remained fairly constant. Intraluminal pressure in the biliary tract paralleled the fluctuation in gallbladder bile acid output, being significantly increased (P less than 0.05) in phases II and III. Periodic contraction of the gallbladder would, therefore, appear to be the principal mechanism for the phasic output of bile during fasting.

The effect of meperidine on the guinea pig extrahepatic biliary tract

The effect of meperidine on the mechanical activity of isolated guinea pig common bile duct (CBD) and gallbladder was studied in vitro. The effect was found to consist of inhibitory and excitatory phases. The inhibitory phase, characterized by a decrease in the response of the CBD and gallbladder to carbachol and electrical stimulation, was seen with concentrations of 10(-6) M or higher. The excitatory phase, seen at high concentrations of meperidine (5 X 10(-5)-10(-4) M), involved an increase in spontaneous contractions of CBD and in the tone of the gallbladder. Neither effect of meperidine was affected by 0.5 X 10(-5) M naloxone. These data indicate that meperidine acts on the biliary tract by a mechanism different from that associated with the effect of morphine.

Effect of morphine on the mechanical activity of common bile duct isolated from the guinea pig

The contractile response of isolated guinea pigs common bile ducts (CBD) to transmural electrical stimulation and the effects of morphine and naloxone was studied. Contractile responses increased as a function of stimulus frequency. In the absence of naloxone morphine inhibited the contractile response to electrical stimulation in a dose-dependent manner. Naloxone prevented the inhibitory effect of morphine on the contractile response to electrical stimulation. We conclude that smooth muscle of the CBD in guinea pig is functional and can contribute to biliary motility, and that opiate receptors exist in nerve elements in the CBD.

Certain aspects of normal and abnormal motility of sphincter of Oddi

Applications of electromyographic and endoscopic manometric techniques in experimental and clinical studies have enhanced our knowledge of the normal physiology and motility disturbances of the sphincter of Oddi. The sphincter of Oddi has an active role in coordinating the time and rate of secretion of biliopancreatic juice into the duodenum. In the opossum, the sphincter of Oddi exhibits spontaneous contractions that migrate distally along the sphincter and expels its contents into the duodenum. Although the motor activity of the sphincter of Oddi is independent from that of the duodenum, there is a correlation between the frequency of bursts of spike potentials in the sphincter of Oddi and the migrating motor complex phases in the duodenum. Abnormal motility of the sphincter of Oddi has been reported during endoscopic manometric evaluation of patients with choledocholithiasis and sphincter of Oddi dyskinesia. Patients with common bile duct stones have an increase in the frequency of retrograde propagation of phasic waves. Elevation of basal pressure as well as an increase in the frequency and amplitude of sphincter of Oddi phasic waves and the common bile duct-duodenum gradient pressure may occur in patients with sphincter of Oddi dyskinesia. Endoscopic manometric studies of the sphincter of Oddi may become an important method to diagnose sphincter of Oddi dyskinesia.

Reflex regulation of flow resistance in the feline sphincter of Oddi by hydrostatic pressure in the biliary tract

Despite wide variations in bile secretion and biliary tract capacitance, the pressure in the bile ducts is fairly constant. Recent studies have demonstrated that both inhibitory and excitatory nerves regulate the activity of the sphincter of Oddi. In the present study, it was consistently found that the resistance by the choledochoduodenal junction to a constant flow, within the physiologic range of hepatic bile output, is reduced when the hydrostatic pressure in the gallbladder and bile ducts is increased from 0 to 10, 0 to 15, and 0 to 20 cmH2O. This response was eliminated by tetrodotoxin or infiltration of the junction between the common bile duct and the cystic duct by mepivacaine, a local anesthetic. The results suggest a homeostatic mechanism during the interprandial periods, when the activity of the sphincter of Oddi is regulated by the distending pressure in the biliary tract. This reflex regulation is mediated by modulation of the activity of inhibitory nerves running along the common bile duct.