Gall-bladder sensitivity to cholecystokinin in patients with gall stones

Cholecystokinin and gastrin receptors targeting in gastrointestinal cancer

Cholecystokinin and Gastrin are amongst the first gastrointestinal hormone discovered. In addition to classical actions (contraction of gallbladder, growth and secretion in the stomach and pancreas), these also act as growth stimulants for gastrointestinal malignancies and cell lines. Growth of these tumours is inhibited by antagonists of the cholecystokinin and gastrin receptors. These receptors provides most promising approach in clinical oncology and several specific radiolabelled ligands have been synthesized for specific tumour targeting and therapy of tumours overexpressing these receptors. Therefore, definition of the molecular structure of the receptor involved in the autocrine/paracrine loop may contribute to novel therapies for gastrointestinal cancer. Hence, this review tries to focus on the role and distribution of these hormones and their receptors in gastrointestinal cancer with a brief talk about the clinical trial using available agonist and antagonist in gastrointestinal cancers.

Gallbladder function and dynamics of bile flow in asymptomatic gallstone disease

AIM: To investigate the effects of gallbladder stones on motor functions of the gallbladder and the dynamics of bile flow in asymptomatic gallstone disease.

METHODS: Quantitative hepatobiliary scintigraphy was performed to detect the parameters of gallbladder motor function [gallbladder ejection fraction (GBEF), gallbladder visualization time (GBVT), gallbladder time to peak activity (GBT_max), gallbladder half emptying time (GBT_1/2), and transit time of bile to duodenum (TTBD)] in 24 patients with asymptomatic cholelithiasis who were diagnosed incidentally during routine abdominal ultrasonographic examination and 20 healthy subjects with normal gallbladder.

RESULTS: Even though there was no significant difference in the clinical and laboratory parameters between the patient and control groups, all parameters of gallbladder function except TTBD were found to differ significantly between the two groups. GBEF in the patient group was decreased (P = 0.000) and GBVT, GBT_max, GBT_1/2 in the patient group were longer (P = 0.000, P = 0.015, P = 0.001, respectively).

CONCLUSION: Our results showed that even if there were not any clinical and laboratory findings, gallbladder filling and emptying could be impaired in patients with gallstone disease.

Targeted disruption of the murine cholecystokinin-1 receptor promotes intestinal cholesterol absorption and susceptibility to cholesterol cholelithiasis

Cholecystokinin (CCK) modulates contractility of the gallbladder, the sphincter of Oddi, and the stomach. These effects are mediated through activation of gastrointestinal smooth muscle as well as enteric neuron CCK-1 receptors (CCK-1Rs). To investigate the potential physiological and pathophysiological functions linked to CCK-1R-mediated signaling, we compared male WT and CCK-1R-deficient mice (129/SvEv). After 12 weeks on either a standard mouse chow or a lithogenic diet (containing 1% cholesterol, 0.5% cholic acid, and 15% dairy fat), small-intestinal transit time, intestinal cholesterol absorption, biliary cholesterol secretion, and cholesterol gallstone prevalence were compared in knockout versus WT animals. Analysis of mice on either the chow or the lithogenic diet revealed that CCK-1R(-/-) animals had larger gallbladder volumes (predisposing to bile stasis), significant retardation of small-intestinal transit times (resulting in increased cholesterol absorption), and increased biliary cholesterol secretion rates. The elevation in bile cholesterol, coupled with a tendency toward gallbladder stasis (due to the absence of CCK-induced contraction), facilitates nucleation, growth, and agglomeration of cholesterol monohydrate crystals; this sequence of events in turn results in a significantly higher prevalence of cholesterol gallstones in the CCK-1R-null mice.

Influence of cholecystitis state on pharmacological response to cholecystokinin of isolated human gallbladder with gallstones

We studied the influence of the inflammatory state of the gallbladder with gallstones on its response to cholecystokinin (CCK). Responses to CCK were evaluated in isolated human gallbladder strips incubated with pharmacological antagonists. Gallbladders from patients with gallstones were classified as having mild and severe chronic cholecystitis. Healthy gallbladders were collected from liver donors. In donor gallbladders, the CCK contraction was abolished with the CCK-A receptor antagonist, L-364718, and significantly reduced by indomethacin. In gallbladders with gallstones, only mild cholecystitis showed a decreased contraction to CCK. In gallbladders with gallstones, no involvement of prostaglandins in the CCK response was observed. In severe cholecystitis, CCK contractile effect was reduced by the serotonin receptor antagonist methysergide. In healthy gallbladder, the contraction provoked by CCK is mediated by CCK-A receptors and modulated by prostaglandins. The presence of gallstones in the gallbladder is correlated with a loss of prostaglandins-modulated CCK contraction. However, the excessive release of serotonin in advanced cholecystitis normalizes the contraction to CCK, suggesting that the state of cholecystitis affects the pool of inflammatory mediators responsible for gallbladder CCK-altered motility.

Management of symptomatic cholelithiasis in pregnancy

BACKGROUND

Symptomatic cholelithiasis occurs in pregnancy in our patient population, some of whom are diabetic. But its management remains controversial. How common is the problem? Is our current policy of management appropriate for our patients?

PATIENTS AND METHODS

The management of 162 pregnant patients admitted over a ten-year period with symptomatic cholelithiasis was evaluated in a retrospective study. The patients were divided into two groups: Group A, 58 patients with diabetes mellitus, and Group B, 104 nondiabetic patients.

RESULTS

Symptomatic cholelithiasis occurred in only 0.3% of our pregnant patients. Of 162 patients, 148 (91.4%) had successful conservative (nonsurgical) management. There was no fetal loss, premature birth, maternal morbidity or mortality. Fourteen patients who had failure of conservative treatment had surgical management. When the postpartum cholecystectomy hospitalization days were added to the total days of admission for the nonoperative cases, there was a significant difference in the mean total number of days of hospitalizations between the surgical cases, 12.4 days, and the nonsurgical cases, 20.5 days (P<0.001), but not in the mean number of hospitalizations, 2.3 versus 3.3.

CONCLUSION

Our current policy of conservative management seems optimal. It has, however, been achieved at the price per patient of 8 extra days of hospitalization. In keeping with recent improvements in surgery and the advent of laparoscopic surgery, a more cost-efficient approach would suggest a more aggressive policy.

Effects of ursodiol or ibuprofen on contraction of gallbladder and bile among obese patients during weight loss

Rapid loss of weight in obese patients is associated with increased saturation of bile with cholesterol, increased nucleation and growth of cholesterol crystals, and gallstones. The aims of this study were to determine the effects of rapid weight loss on contraction of the gallbladder and to evaluate the effects of ursodiol and ibuprofen on saturation, nucleation and growth, and contraction. Forty-seven obese patients entering a very low calorie dietary program were randomized to receive ursodiol, 1200 mg/day, ibuprofen, 1600 mg/day, or placebo for 12 weeks. Contraction of the gallbladder to a liquid meal was evaluated by ultrasonography, and duodenal bile was collected initially and after six and 12 weeks. Diet caused reduced contraction of the gallbladder, increased cholesterol saturation, and increased nucleation and growth of crystals. Ursodiol reduced saturation and prevented increases in nucleation and growth and contraction. Ibuprofen prevented the increase in saturation and the reduction in contraction with a trend opposing the increase in nucleation and growth. In conclusion, during dieting, contractility of the gallbladder to meals is reduced. The effectiveness of ursodiol in preventing gallstones may be explained partially by effects on contraction. Ibuprofen deserves further study because of its effects on saturation, nucleation and growth, and contraction.

Gallbladder motility, gallstones, and the surgeon

Cholecystectomy is one of the commonest surgical procedures in the Western world, with more than half a million procedures performed annually in the United States alone. In recent years, studies of gallstone pathogenesis and gallbladder disease have increasingly focused on abnormal gallbladder motility in the pathogenesis of some, if not all, gallbladder conditions. The control of gallbladder motility is complex and depends on an intricate interplay of neural and hormonal factors. An understanding of the control of gallbladder motility is crucial to the understanding of the mechanisms of gallstone formation and may help to explain the failure to cure symptoms after cholecystectomy in up to one third of patients. The purpose of this article is to outline mechanisms controlling gallbladder motility, examine recent developments in our understanding of this complex process, and relate changes in motility to common disease conditions of the gallbladder. The role of altered motility in the pathogenesis of gallstones is discussed and the effects of commonly performed surgical procedures such as truncal vagotomy and cholecystectomy on upper gut physiology are reviewed.

Postprandial gallbladder motor function: refilling and turnover of bile in health and in cholelithiasis

BACKGROUND & AIMS

Impaired gallbladder emptying is implicated in gallstone disease. Ultrasonography and scintigraphy have shown conflicting results because the former is influenced by postprandial refilling, whereas the latter is not influenced by refilling. The aim of this study was to measure postprandial refilling and turnover of bile by combining the two techniques.

METHODS

Simultaneous scintigraphy and ultrasonography were used in 14 patients with gallstones and 11 healthy controls. Measurements were performed while the patients were fasting and at 10-minute intervals after a standard meal for 90 minutes, and the measurements were used to calculate postprandial refilling, turnover of bile (in milliliters), and turnover index.

RESULTS

Ultrasonography and scintigraphy provided different gallbladder emptying patterns. Compared with controls, patients with gallstones had impaired emptying by both scintigraphy (P < 0.0001) and ultrasonography (P < 0.01). Postprandial refilling and turnover were both reduced between 60 and 90 minutes (P < 0.05), and the turnover index was markedly reduced (1.8 vs. 3.5; P < 0.001).

CONCLUSIONS

Simultaneous scintigraphy and ultrasonography provide a new model of gallbladder motor function showing that refilling begins immediately postprandially. In healthy controls, the gallbladder postprandially handles up to six times its basal volume within a period of 90 minutes, but this turnover of bile is markedly reduced in cholelithiasis causing a reduced washout effect of the gallbladder contents, including cholesterol crystals.

Physiology and pathophysiology of gallbladder motility

Most significant gallbladder disease is associated with gallbladder stasis. Gallbladder motility is controlled by a complex interplay of hormonal and neural factors. Experimental and clinical studies have demonstrated impaired motility in gallstone disease, and experimental evidence indicates that motility disturbances precede gallstone formation. The ability to measure gallbladder motility clinically has also resulted in better diagnosis and treatment for patients with chronic acalculous cholecystitis.

Effect of oral erythromycin on gallbladder motility in normal subjects and subjects with gallstones

The action of the motilin receptor agonist erythromycin on human gallbladder contraction, measured by ultrasound, both in normal subjects and those with gallstone disease was studied. In 17 normal subjects, oral erythromycin administration (500 mg; vs. placebo) reduced fasting gallbladder volume at 2 hours (26.2 vs. 19.0 mL; P less than 0.001), and postprandial residual gallbladder volume (9.0 vs. 4.4 mL; P less than 0.001) and the rate constant of gallbladder emptying following the meal was significantly increased. Erythromycin also reduced fasting and residual gallbladder volumes in 13 patients with gallstone disease: in 6 who underwent cholecystolithotomy, fasting volume was 29.5 vs. 22.3 mL (P less than 0.05) and residual volume was 17.7 vs. 6.5 mL (P less than 0.05), and in 7 with gallstones in situ, fasting volume was 23.8 vs. 14.3 mL (P less than 0.05) and residual volume was 17.2 vs. 5.0 mL (P less than 0.05). In 7 of 8 subjects with gallstones and impaired gallbladder emptying, the gallbladder emptied normally following administration of erythromycin, and in 3 of the other 5 gallstone subjects gallbladder emptying was increased. In 6 normal subjects given erythromycin three times weekly for 1 month, the effect was maintained (fasting volume, 18.8 mL, P less than 0.001; residual volume, 3.7 mL, P less than 0.001). Oral erythromycin significantly reduces fasting and postprandial residual gallbladder volumes in both normal subjects and subjects with gallstones and reverses the gallbladder motility defect found in a proportion of subjects with gallstones. This effect is maintained for a month in normal subjects.

Increased volume and decreased emptying of the gallbladder in large (morbidly obese, tall normal, and muscular normal) people

Impaired gallbladder emptying has been suggested as a possible factor in the pathogenesis of gallstones. Obese people have an increased incidence of gallstones, but there is no evidence of this in nonobese large people. This study was undertaken to determine if abnormal gallbladder motility is present in obese people. Fasting gallbladder volumes were determined using real-time ultrasound in 18 morbidly obese subjects whose weights were in a steady state [45 kg (100 lb) over ideal weight or twice expected weight for age and height; 9 males, 9 females], 18 age- and sex-matched volunteers of average size, and 18 nonobese large normal males (9 tall, 9 muscular). Gallbladder emptying studies with 99mtechnetium-diisopropyliminodiacetic acid were performed using 200 ml of 10% cream as a stimulus. The small-volume liquid fatty meal contained 113indium-diethylenetriaminepentaacetic acid to control for differences in gastric emptying in obesity. The gallbladder emptying rate in large people, both obese and nonobese, was less than that in normals of average size (p = 0.05). Fasting gallbladder volumes in large people were: obese, 41 ml (37-66 ml) (median; 95% confidence limits); nonobese large normal, 40 ml (27-43 ml). These values were greater than in normals of average size [17 ml (14-21 ml) (p = 0.03)]. Postprandial gallbladder volumes were also greater in large people: obese, 15 ml (8-23 ml); nonobese large normal, 20 ml (13-23 ml) compared with 2 ml (1-5 ml) in normals of average size (p less than 0.05). There were no differences between obese and nonobese large people. There were no differences in gastric emptying rates or in cholecystokinin, gastrin, motilin, and secretin release between obese and normal subjects. Gallbladder volume is crudely proportional to body size. Although fasting and postprandial volumes are greater in obesity, this is also present in nonobese, relatively size-matched controls. These data do not support a role for impaired gallbladder emptying in gallstone formation in obese patients whose weights are in a steady state.

Gallbladder contraction in patients with pigment and cholesterol stones

Thirty gallbladders were studied in vitro; 5 had black pigment stones and 25 contained manifestations of excess cholesterol in bile. Of the 25, 14 had cholesterol stones, 7 had macroscopic cholesterolosis, and 4 had cholesterol crystals. There were no differences in basal active tension among these groups, but the force of spontaneous phasic contractions was reduced in gallbladders with cholesterol stones, cholesterolosis, and cholesterol crystals compared with specimens with pigment stones (p less than 0.001). The forces developed in response to cholecystokinin-8 (10(-10)-10(-6) M), acetylcholine (10(-7)-10(-3) M), and potassium chloride (20-60 mM) were greater in strips from specimens with pigment stones than in strips from specimens with cholesterol stones or cholesterolosis (p less than 0.001). In cholesterol stones and cholesterolosis specimens, relatively strong muscle strips had similar responses to 10(-6) M cholecystokinin-8 in normal calcium (2.5 mM) and in the absence of extracellular calcium. Weaker muscle strips had a reduced response to cholecystokinin-8 in the absence of extracellular calcium (p less than 0.01). It is concluded that muscle strips exposed to bile with excess cholesterol have a reduced contractility compared with muscle strips from specimens with pigment stones; this impaired contractility precedes gallstone formation, and results from muscle dysfunction.

Functional and biochemical characterization of the human gallbladder muscularis cholecystokinin receptor

Gallbladders removed at cholecystectomy are a potentially useful source of human receptor for the gastrointestinal peptide hormone cholecystokinin (CCK). Seven healthy gallbladders (removed incidentally at time of resection of hepatic metastases) and 50 diseased gallbladders were studied. Cholecystokinin radioligand binding to an enriched plasma membrane preparation from these tissues was shown to be rapid, reversible, temperature-dependent, saturable, specific, and high-affinity. Computer analysis of equilibrium binding data using the Ligand program best fit a single class of binding sites with Kd = 1.0 +/- 0.1 nM (mean +/- SEM). This was similar in health and disease, with no apparent differences related to age, gender, or body habitus. The structural specificity for binding to this site correlated well with relative potencies for CCK-gastrin peptides to stimulate gallbladder contraction. To biochemically characterize this receptor, we used a battery of reagents, including "long" (125I-Bolton Hunter-CCK-33) and "short" 125I-D-Try-Gly-[(Nle28,31)CCK-26-33] probes that were cross-linkable through their amino terminus and a monofunctional probe with a photolabile group at its carboxyl terminus 125I-D-Tyr-Gly[(Nle28,31,pNO2-Phe33)CCK-26-33]. All probes specifically labeled a human gallbladder muscularis protein of Mr = 85,000-95,000, which was also independent of diagnosis. Labeling of this band was inhibited in a concentration-dependent manner by CCK-8 and by L-364,718. Thus, the CCK receptor present on the very common surgically removed human gallbladder is functionally and biochemically intact and is useful for further characterization.

Plasma cholecystokinin and gallbladder responses to intraduodenal fat in gallstone patients

Impaired gallbladder emptying is one of the various factors suggested to be involved in the pathogenesis of gallstones. The present study was undertaken to determine whether gallbladder emptying, endogenous cholecystokinin (CCK) secretion, or their interrelation is altered in patients with gallstones. After intraduodenal administration of 60 ml corn oil, plasma CCK concentration was measured by a sensitive and specific radioimmunoassay and gallbladder emptying by cholescintigraphy. Patients with gallstones (N = 20) produced significantly less endogenous CCK (105 +/- 17 pmol/liter 60 min; P less than 0.001) than control subjects (191 +/- 11 pmol/liter 60 min, N = 20); gallbladder emptying in the patients was significantly decreased at 5, 10, 40, 45, and 50 min but the reduction in gallbladder emptying did not reach statistical significance at 60 min (patients 44 +/- 8%, control subjects 60 +/- 4%). In addition, the gallbladder responsiveness to intravenous infusion of the synthetic CCK analog cerulein was investigated. Based on the results of gallbladder emptying in response to endogenous and exogenous CCK, four subgroups of gallstone patients were identified: (1) a group (N = 7) with normal gallbladder sensitivity to CCK, (2) a group (N = 6) with significantly increased gallbladder sensitivity to CCK, (3) a group (N = 6) with impaired gallbladder emptying after corn oil due to a significantly reduced endogenous CCK secretion but with normal gallbladder sensitivity to CCK, and (4) one patient whose gallbladder was unresponsive to CCK and was found to have chronic cholecystitis at surgery.

Technetium-99m-iminodiacetic acid organic anions: review of biokinetics and clinical application in hepatology

Technetium-99m-labeled iminodiacetic acid analogs are a new class of organic anions, taken up and secreted by hepatocyte into hepatic bile by a carrier-mediated organic anion pathway. They provide a new dimension in the assessment of pathophysiology and morphology of the hepatobiliary system. The amount of uptake and the rapidity of its elimination from the liver is dependent upon the structural configuration of the agent as well as the functional integrity of the hepatocyte and the patency of the biliary system. The clinical areas for application are wide and include most of the hepatobiliary diseases. Technetium-99m-iminodiacetic acid, an agent well suited for both planar and single photon tomographic scintigraphy, is ideal for early diagnosis prior to anatomical changes in the hepatobiliary system. The data collection directly from the liver provides quantitation of both regional and global liver diseases. The count-based method for measuring gallbladder emptying overcomes the theoretical disadvantages of geometric tests. Biokinetics and current clinical application of six of the 99mTc-iminodiacetic acid agents are reviewed, and the potential future clinical and research areas of application are indicated.

Clinical application of the cholecystokinin provocation test

This paper reviews the value of administration of cholecystokinin (CCK) in the assessment of patients thought to have acalculous biliary pain. The literature contains conflicting reports and there is no unequivocal evidence to support the use of CCK provocation tests as a basis for deciding the need for cholecystectomy.

Correlation of cholecystokinin receptors with gallbladder contractility in patients with gallstones

The authors have previously identified two groups of patients with gallstones: those whose gallbladders contract the same as those of normal volunteers and show an increased sensitivity to endogenous cholecystokinin (CCK) ("contractors") and those whose gallbladders are relatively unresponsive ("noncontractors"). To define the mechanism responsible for these differences in contractility, the authors have measured CCK receptors on gallbladder muscle of patients with gallstones. Twenty-three patients with gallstones and 10 healthy volunteers (controls) fasted overnight. Simultaneous plasma samples for radioimmunoassay of CCK release and ultrasonographic measurements of gallbladder volume were obtained before and at intervals for 60 minutes after ingestion of Lipomul. Patients with gallstones had cholecystectomy, and CCK receptors were determined on cell membranes from gallbladder specimens by use of radiolabeled analogs of CCK-8-SO4. Histologic sections were graded for the degree of inflammation and scarring. Thirteen patients with gallstones were identified as contractors and 10 as noncontractors. Basal gallbladder volumes were not significantly different between patients in either group. The total integrated output of CCK for contractors was 1.6 +/- 0.2 ng X min/ml compared with 5.5 +/- 1.2 ng X min/ml for controls, while the integrated output for noncontractors was 11.1 +/- 2.1 ng X min/ml. Contractors had a higher number of CCK-binding sites (27.6 +/- 6.8 fmol/mg protein) than did noncontractors (4.8 +/- 1.0 fmol/mg protein). CCK receptors in gallbladders of all patients with gallstones correlated closely with gallbladder motility (y = 1.149, x = 0.624, r = 0.7, p less than 0.001). Although contractors had more mild inflammation and scarring, 40% of noncontractors had mild inflammation and scarring; there was no correlation. A decrease in CCK receptors may be an early event in the pathogenesis of gallstone formation by causing a decrease in gallbladder motility in some patients.

Effects of artificial depletion of the bile acid pool in man

In order to elucidate the relationship between bile acid pool size and cholesterol saturation index of fasting state gall bladder bile, we artificially depleted the bile acid pool in 12 healthy volunteers. Bile acid pool size decreased from 7.6 +/- 0.9 to 5.8 +/- 0.7 mmol (mean +/- SEM, p less than 0.01), and saturation index of fasting state gall bladder bile increased from 0.93 +/- 0.07 to 1.18 +/- 0.07 (p less than 0.001). There was no alteration in saturation index of basal or stimulated hepatic bile. There was no change in gall bladder storage of basal hepatic bile, nor in the proportion of the bile acid pool stored in the gall bladder. The bile acid mass in the gall bladder fell from 4.9 +/- 0.5 to 3.4 +/- 0.4 mmol (p less than 0.05) and phospholipid mass from 1.6 +/- 0.3 to 1.2 +/- 0.2 mmol (p less than 0.05), but there was no change in cholesterol mass. The gall bladder volume fell from 30 +/- 4 to 18 +/- 2 ml (p less than 0.01). These results suggest that artificial depletion of the bile acid pool increased saturation index of fasting state gall bladder bile without altering saturation index of basal or stimulated hepatic bile; it probably increased the ratio of basal: stimulated hepatic bile within the gall bladder by decreasing gall bladder storage of stimulated hepatic bile.

Effects of a pharmacological dose of cholecystokinin on bile acid kinetics and biliary cholesterol saturation in man

In order to study the mechanisms influencing bile acid pool size and cholesterol saturation index of fasting gall bladder bile, eight obese volunteers were placed on a low calorie diet for six weeks, and given intramuscular injections of a pharmacological dose of cholecystokinin octapeptide (CCK-OP, 5 micrograms) at mealtimes for half that period (alternating order). During CCK-OP administration, postprandial emptying of the gall bladder (mean +/- SEM) increased from 58 +/- 11% to 82 +/- 5% (p less than 0.005), and small intestinal transit time decreased from 205 +/- 27 to 178 +/- 26 minutes (NS). Bile acid pool size decreased from 4.6 +/- 0.3 to 3.1 +/- 0.3 mmol (p less than 0.001), while fractional turnover rate for chenodeoxycholic acid increased from 0.23 +/- 0.02 to 0.36 +/- 0.03 per day (p less than 0.005), suggesting an increase in recycling frequency of the pool. Synthesis rate was unchanged (0.43 +/- 0.08 vs 0.44 +/- 0.07 mmol/day), suggesting a new steady state. The cholesterol saturation index of fasting gall bladder bile increased in all subjects from 1.3 +/- 0.1 to 1.6 +/- 0.1 (p less than 0.005). Fasting gall bladder volume was reduced from 29 +/- 4 to 20 +/- 7 ml (p less than 0.01). Fractional turnover rate on the two regimens correlated with gall bladder emptying (n = 16, r = 0.61, p less than 0.01), but not with small intestinal transit time (r = 0.07, NS). Bile acid pool size correlated with fractional turnover rate (r = -0.73, p less than 0.005) and with cholesterol saturation index (r = -0.56, p less than 0.025). These findings suggest that CCK influences bile acid kinetics and cholesterol saturation index of fasting gall bladder in man; and that these effects of CCK are mainly mediated via alterations in gall bladder emptying rather than through alterations in small intestinal transit rate.

Gallbladder filling and emptying during cholesterol gallstone formation in the prairie dog. A cholescintigraphic study

We studied gallbladder bile flow before, during, and after cholesterol gallstone formation in the prairie dog using infusion cholescintigraphy with 99mTc-diethyl iminodiacetic acid. In 18 fasting animals partitioning of bile between gallbladder and intestine was determined every 15 min for 140 min, and gallbladder response to cholecystokinin (5 U/kg X h) was calculated from the gallbladder ejection fraction. Ten prairie dogs were then placed on a 0.4% cholesterol diet and 8 on a regular diet, and the studies were repeated 1, 2, and 6 wk later. The proportion of hepatic bile that entered the gallbladder relative to the intestine varied from one 15-min period to the next, and averaged 28.2% +/- 5.1% at 140 min. Partial spontaneous gallbladder emptying (ejection fraction 11.5% +/- 5.6%) was intermittently observed. Neither the number nor the ejection fraction of spontaneous gallbladder contractions changed during gallstone formation. By contrast, the percent of gallbladder emptying in response to cholecystokinin decreased from 72.1% +/- 5% to 25.9% +/- 9.3% (p less than 0.025) in the first week and was 14.3% +/- 5.5% at 6 wk (p less than 0.01 from prediet values, not significant from first week). Gallbladder filling decreased from 28.2% +/- 5.1% to 6.7% +/- 3% (p less than 0.01), but this change was only observed after 6 wk, when gallstones had formed. This study shows that bile flow into the gallbladder during fasting is not constant; the gallbladder contracts intermittently; gallbladder emptying in response to exogenous cholecystokinin is altered very early during gallstone formation; and gallbladder filling remains unaffected until later stages, when gallstones have formed.

Effect of caerulein in patients with biliary colic pain

A randomized placebo-controlled double-blind trial was carried out in 24 patients with biliary colic pain in order to evaluate the analgesic effect of caerulein (CRL). Caerulein (1 ng/kg . min infused intravenously over 15 min) showed an analgesic effect that was significantly higher than placebo (p less than 0.001). The analgesic action of CRL was not inhibited by naloxone (0.4 mg intravenously, administered two times). Further, the effect of i.v. CRL or saline on artificially induced biliary tree hypertension was studied in 7 patients with a T-tube common bile duct drainage. During saline intravenous administration, increasing biliary tree pressure resulted in pain in 5 patients, with the threshold for pain being 40 cmH2O. During CRL intravenous infusion, significantly higher perfusion pressures were required to achieve a given common bile duct pressure and the pressure threshold for pain was not reached. Consequently, pain was prevented in all patients. These data suggest that CRL relieves biliary colic pain by reducing biliary tract pressure.

Abnormal gallbladder emptying in a subgroup of patients with gallstones

Gallbladder stasis has been implicated in gallstone formation. Gallbladder filling and emptying were quantitated by computer-assisted cholescintigraphy in 41 normal subjects versus 26 patients with gallstones. Gallbladder contraction was induced by low-dose (1.2 U/kg . h) cholecystokinin infusion. Gallstone patients exhibited normal gallbladder filling, but emptying was significantly (p less than 0.01) reduced compared with controls. On closer inspection, the patients fell into two subgroups, separated by t1/2, the time to empty 50% of gallbladder contents, 19.1 min (mean + 2 SD of control). Fifteen patients (57.7%) with a normal t1/2 (less than 19.1 min) exhibited both normal filling and normal emptying. The remaining 11 patients (43.3%) with t1/2 greater than 19.1 min had grossly abnormal gallbladder emptying, significantly (p less than 0.001) different from both the previous patient subgroup and the controls. There was no significant difference in age, sex, prevalence of obesity, presence or absence of biliary colic, and gallstone size, number, or calcification between these two subgroups. Thus, defective gallbladder emptying is evident in a subgroup of gallstone patients, and is independent of clinical features, stone size, and number. Impaired emptying should be considered when assessing pathogenesis or medical therapy.

Abnormal gallbladder emptying in patients with gallstones

In this study, gallbladder and gastric emptying were compared in 15 normal subjects and 15 patients with gallstones. A noninvasive technique which used two gamma-emitting radiopharmaceutical agents to image the gallbladder and stomach simultaneously was employed. Technetium-99m-HIDA was used as a gamma-emitting marker for the gallbladder and indium-111-DTPA was mixed with a standard liquid meal in order to stimulate gallbladder emptying and to measure gastric emptying. In patients with gallstones, gallbladder emptying was diminished significantly compared to normal subjects. In contrast, emptying of the stomach was normal. The gallbladder emptying responses to octapeptide of cholecystokinin, administered either as bolus or infusion doses, were similar in normal subjects and patients with gallstones. These studies suggest that gallbladder emptying may be abnormal in patients with gallstones. The explanation for this abnormality and its relationship to the development of gallstones has not been determined.

Correlation between release of cholecystokinin and contraction of the gallbladder in patients with gallstones

The role of endogenously released cholecystokinin (CCK) in mediating gallblader (GB) contraction was evaluated in 12 normal volunteers and 24 patients with gallstones (11 additional gallstone patients were excluded because of failure of adequate ultrasonographic visualization). CCK concentrations before and after oral administration of fat (Lipomul((R))) were measured by a specific radioimmunoassay. CCK release was correlated with changes in GB volume determined simultaneously by ultrasonography. On the basis of gallbladder contraction and operative findings, gallstone patients were divided into "contractors" (14), "noncontractors" (6), and "hydrops" (4). Lipomul caused prompt release of CCK in normal volunteers and all groups of gallstone patients. The changes (basal to peak) in plasma CCK (pg/ml) for the different groups were as follows: normal volunteers (108 +/- 9 to 200 +/- 16), contractors (77 +/- 10 to 128 +/- 13), noncontractors (59 +/- 7 to 159 +/- 38), and hydrops (43 +/- 5 to 113 +/- 47). The total integrated output of CCK (0-60 min) was greater in normal volunteers (3975 +/- 762 pg-min/ml) than in contractors (1530 +/- 567 pg-min/ml). Lipomul caused similar GB contraction in normal volunteers and contractors (from basal volumes to maximal contraction); these changes were from 19.5 +/- 2.3 ml to 5.6 +/- 1.0 ml in normal volunteers, and from 19.6 +/- 3.2 to 5.2 +/- 1.0 in contractors. Plasma concentrations of CCK and GB volume were highly correlated in the 12 normal volunteers (r = -0.89, p < 0.01) and in the 14 contractors (r= -0.99, p < 0.01)), but the GB was significantly (p < 0.01) more sensitive to changes in plasma CCK in the gallstone contractors than in the normal volunteers. The authors suggest that there may be two groups of gallstone patients, noncontractors and contractors. Stasis may be important in the pathogenesis of gallstones in the noncontractors, whereas in contractors, the authors speculate that an abnormality in the CCK-gallbladder relationship (characterized by diminished CCK release and increased GB sensitivity to CCK) may be involved in the evolution of the disease.

Stasis before gallstone formation: altered gallbladder compliance or cystic duct resistance?

Gallbladder stasis occurs before gallstone formation and provides the link between the hepatic secretion of supersaturated bile and cholesterol cholelithiasis. We recently observed that cystic duct resistance increases while sphincter of Oddi resistance is unchanged in the presence of lithogenic bile without gallstones. Whether alterations in gallbladder function also lead to gallbladder stasis has been unclear. Therefore, we tested the hypothesis that before gallstone formation, stasis results from increased cystic duct resistance and altered gallbladder compliance. Adult, male prairie dogs were fed either a trace cholesterol (control) or a 0.4 percent cholesterol-enriched diet. Cystic duct resistance increased but gallbladder compliance was unchanged before gallstone formation. A significant correlation (p less than 0.001) was found between the lithogenic index and cystic duct resistance in pregallstone animals. We conclude that increased resistance to flow across the cystic duct, and not altered gallbladder compliance, is etiologically related to bile stasis, an important event in gallstone formation.

Pathogenesis of cholesterol gallstones

The factors leading to cholesterol cholelithiasis are probably multiple. Although the secretion of bile supersaturated with cholesterol seems to be a common feature among all patients who form cholesterol stones, a variety of pathophysiologic events can produce an increase in lithogenicity. Dietary factors, particularly in the grossly obese, lead to an absolute increase in secretion of cholesterol into bile. Occasionally, excessive loss of the bile salt pool, for example with regional ileitis, may decrease the ability of bile salts to solubilize cholesterol. In many other, subtle alterations in the enterohepatic circulation of bile salts may adversely affect solubility by both decreasing the secretion of bile salts and increasing the secretion of cholesterol. Regardless of its cause, supersaturation of bile with cholesterol appears to be a prerequisite for gallstone formation. However, additional factors within the gallbladder, such as increased secretion of glycoprotein, increased absorption of fluids, infection, and stasis, appear to contribute to the formation of macroscopic stones.