Sequential changes in biliary lipids and gallbladder ion transport during gallstone formation.

OBJECTIVE: This study sought to correlate gallbladder (GB) Na+ and Cl-) fluxes with biliary lipid composition during the various stages of gallstone (GS) formation. SUMMARY BACKGROUND DATA: GS formation is associated with altered GB ion transport and increased biliary lipid and Ca2+ concentrations. Nonetheless, the longitudinal relationship between ion transport and biliary lipid changes during GS formation has not been defined. METHODS: Prairie dogs were fed standard (n = 18) or 1.2% cholesterol-enriched (n = 30) diets for 4 to 21 days. Hepatic and GB bile were analyzed for lipids and Ca2+. Animals were designated either Pre-Crystal, Crystal, or GS based on absence or presence of crystals or GS, respectively. GBs were mounted in Ussing chambers, electrophysiologic parameters were recorded, and unidirectional Na+ and Cl- fluxes measured. RESULTS: Short-circuit current and potential difference were similar during Pre-Crystal and Crystal stages but significantly reduced during GS stage compared to controls and Pre-Crystals. Transepithelial resistance was similar in all groups. Net Na+ absorption was increased during Pre-Crystal but decreased during GS stage due to increased mucosa-to-serosa and serosa-to-mucosa flux, respectively. Increased serosa-to-mucosa flux of both Na+ and Cl- characterized the Crystal stage. Biliary lipids and Ca2+ increased progressively during various stages of GS formation and correlated positively with unidirectional fluxes of Na+ and Cl-. CONCLUSION: GB epithelial ion transport changes sequentially during GS formation, with the early Pre-Crystal stage characterized by increased Na+ absorption, and the later Crystal stage accompanied by prosecretory stimuli on Na+ and Cl- fluxes, which may be due to elevated GB bile Ca2+ and total bile acids.

Protein kinase C regulates prairie dog gallbladder ion transport.

BACKGROUND: Gallstone formation is characterized by increased biliary calcium (Ca2+) level and altered gallbladder absorption. Recent studies suggest that luminal Ca2+ regulates gallbladder ion transport via intracellular calcium ([Ca2+]ic). Ca2+-calmodulin and protein kinase C (PKC) are two major systems through which [Ca2+]ic carries out second-messenger functions in many cell types. We have previously shown that Ca2+-calmodulin regulates basal gallbladder ion transport in prairie dog. The present study tests the hypothesis that PKC is also essential in regulation of gallbladder ion transport in this model. METHODS: The role of PKC in regulation of gallbladder ion transport was determined by studying the effects of phorbol esters, synthetic analogues of diacylglycerol, which directly activates PKC. Gallbladders were mounted in Ussing chambers, and standard electrophysiologic parameters were recorded after exposing tissues to either 10(-5) mol/L of 4-alpha-phorbol 12,13-didecanoate (PDD), 4-beta-phorbol 12-myristate 13-acetate, 4-beta-phorbol 12,13-dibutyrate (PDB), or 10(-4) mol/L serotonin. Unidirectional Na+, Cl-, and H2O fluxes were measured before and after treatment with only inactive PDD and most active PDB. RESULTS: Mucosal and serosal exposure of tissues to either 4-beta-phorbol 12-myristate 13-acetate or PDB resulted in a decrease in short-circuit current and transepithelial potential difference without any change in tissue resistance. Serotonin induced similar changes in gallbladder electrical properties. PDB caused an inhibition of mucosal to serosal fluxes of Na+, Cl-, and H2O, with a decrease in net Na+ absorption, an increase in net Cl- secretion, and a conversion of net H2O absorption to net H2O secretion. Serosal-to-mucosal fluxes of Na+, Cl-, and H2O did not change. Inactive PDD had no effect on either electrophysiologic parameters or ion and water fluxes. Pretreatment of tissues with PKC antagonist 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine blocked the phorbol ester-induced inhibition of ion transport. CONCLUSION: PKC regulates gallbladder ion transport in the prairie dog by inhibiting Na+ absorption and stimulating Cl- secretion.

Open cholecystectomy. A contemporary analysis of 42,474 patients.

OBJECTIVE: This study evaluated, in a large, heterogeneous population, the outcome of open cholecystectomy as it is currently practiced. SUMMARY BACKGROUND AND DATA: Although cholecystectomy has been the gold standard of treatment for cholelithiasis for more than 100 years, it has recently been challenged by the introduction of several new modalities including laparoscopic cholecystectomy. Efforts to define the role of these alternative treatments have been hampered by the lack of contemporary data regarding open cholecystectomy. METHODS: A population-based study was performed examining all open cholecystectomies performed by surgeons in an eastern and western state during a recent 12-month period. Data compiled consisted of a computerized analysis of Uniformed Billing (UB-82) discharge analysis information from all non-Veterans Administration (VA), acute care hospitals in California (Office of Statewide Planning and Development [OSHPD]) and in Maryland (Health Services Cost Review Commission [HSCRC]) between January 1, 1989, and December 31, 1989. This data base was supplemented with a 5% random sample of Medicare UB-82 data from patients who were discharged between October 1, 1988, and September 30, 1989. Patients undergoing cholecystectomy were identified based on diagnosis-related groups (DRG-197 and DRG-198), and then classified by Principal Diagnosis and divided into three clinically homogeneous subgroups: acute cholecystitis, chronic cholecystitis, and complicated cholecystitis. RESULTS: A total of 42,474 patients were analyzed, which represents approximately 8% of all patients undergoing cholecystectomy in the United States in any recent 12-month period. The overall mortality rate was 0.17% and the incidence rate of bile duct injuries was approximately 0.2%. The mortality rate was 0.03% in patients younger than 65 years of age and 0.5% in those older than 65 years of age. Mortality rate, length of hospital stay, and charges were all significantly correlated (p < 0.001) with age, admission status (elective, urgent, or emergent), and disease status. CONCLUSIONS: These data indicate that open cholecystectomy currently is a very safe, effective treatment for cholelithiasis and is being performed with near zero mortality. The ultimate role of laparoscopic cholecystectomy needs to be defined in the context of current and contemporary data regarding open cholecystectomy.

Early and long-term effects of colectomy and endorectal pullthrough on bile acid profile.

OBJECTIVE: Although total colectomy with mucosal proctectomy and endorectal pullthrough affects two sites critical to the enterohepatic circulation of bile acids, little information is available regarding the manner in which normal digestive physiology is altered by these procedures. This study defines the early and long-term effects of colectomy and endorectal pullthrough on bile acid profile and the long-term effects on biliary lipid metabolism. SUMMARY BACKGROUND DATA: Specific changes in bile acid absorption have been reported in patients after ileal resection. Recent studies from our laboratory indicate that in the early postoperative period, colectomy with endorectal pullthrough causes a significant decrease in gallbladder bile concentrations of total bile acids, cholesterol, phospholipids, and calcium. The observation by several authors that the pouch undergoes morphologic and perhaps functional adaptation suggest that these changes may be transient and perhaps reversible. METHODS: These studies were done in an awake, unanesthetized canine model that allows periodic sampling of gallbladder bile without creation of an external biliary fistula and its associated sequelae. Animals were ultimately randomly assigned to either laparotomy and gallbladder cannulation (N = 6), or gallbladder cannulation with total colectomy and ileorectal anastomosis (N = 7), or biliary cannulation, colectomy, mucosal proctectomy and endorectal pullthrough with ileal reservoir (N = 5). RESULTS: Six weeks after operation, colectomy and ileorectal anastomosis were associated with a significant alteration in the relative composition of bile acids in gallbladder bile. These early changes were manifested by a significant (p < 0.05) increase in taurocholic acid and a concomitant decrease in taurodeoxycholic acid. These changes became even more pronounced in the ileorectal anastomosis group 12 weeks after colectomy and ileorectostomy. Although similar changes in the relative concentrations of individual bile acids occurred in the 6-week endorectal animals, bile acid profile was restored to normal by 12 weeks. CONCLUSIONS: Colectomy with ileorectal anastomosis leads to early and significant changes in bile acid profile, which persist and become even more pronounced with time. In contrast, the construction of an ileal reservoir after colectomy facilitates restoration of a normal bile acid profile. We propose that these alterations in bile acid metabolism result from adaptation of the ileal reservoir as its mucosa assumes functional characteristics of normal colon.

Prostaglandin E2 stimulates ion transport in prairie dog gallbladder.

The effects of prostaglandins, and specifically prostaglandin E2, on gallbladder ion transport were examined in the prairie dog. Gallbladders were mounted in an Ussing chamber and baseline short-circuit current, potential difference, and tissue resistance were measured. Addition of arachidonic acid (10(-4) M, mucosal surface) produced sustained elevations in short-circuit current and potential difference (P < 0.05), with mild reductions in resistance. In a second set of tissues, indomethacin exposure (10(-6) M) resulted in a significant (P < 0.02) decrease in short-circuit current and potential difference, with an increase in resistance. Subsequent addition of prostaglandin E2 (10(-7) M, serosal surface) fully reversed these changes and led to a significant increase in short-circuit current and potential difference (P < 0.001) with a return of resistance to baseline values. These findings suggest that endogenous prostaglandins mediate gallbladder ion transport.

Cholecystectomy. The impact of socioeconomic change.

The impact of our evolving health care system on a commonly performed surgical procedure, cholecystectomy, was assessed in a county-subsidized and private university hospital setting. Although condition on admission, use of resources, and outcome were unchanged in the private setting between 1980 and 1988, significant differences were noted among the largely uninsured patients at the county facility during this same time interval. There was a significant increase in the acuity of illness among patients undergoing cholecystectomy at the county hospital in 1988 as compared with 1980. These data suggest that alterations in reimbursement strategies and allocation of resources are significantly impacting on patient care, particularly in nonprivate health care facilities.