Alcoholic versus nonalcoholic cirrhosis in a randomized controlled trial of emergency therapy of bleeding varices.

BACKGROUND: It has been proposed that portal-systemic shunts be avoided in alcoholic cirrhotics because survival rate is allegedly lower in alcoholics than in nonalcoholics. We examined this issue in a randomized controlled trial. METHODS: Two hundred eleven unselected, consecutive patients with cirrhosis and bleeding esophageal varices were randomized to endoscopic sclerotherapy (EST) (n = 106) or emergency portacaval shunt (EPCS) (105). Treatment was initiated within 8 h. EST failure was treated by rescue portacaval shunt (PCS). Ten-year follow-up was 96%. RESULTS: Results strongly favored EPCS over EST (P < 0.001). Among EPCS patients, 83% were alcoholic and 17% nonalcoholic. Outcomes were (1) permanent control of bleeding 100% versus 100%; (2) 5-y survival 71% versus 78%; (3) encephalopathy 14% versus 19%; (4) yearly charges $38,300 versus $43,000. CONCLUSIONS: EPCS results were similar in alcoholic and nonalcoholic cirrhotics. EPCS is an effective first line emergency treatment in all forms of cirrhosis, including alcoholic.

Child-Turcotte score versus MELD for prognosis in a randomized controlled trial of emergency treatment of bleeding esophageal varices in cirrhosis.

BACKGROUND AND AIMS: Bleeding esophageal varices is responsible for much of the high mortality rate in cirrhosis. An important objective of management of bleeding varices is to develop reliable tools for predicting survival, controlling bleeding and encephalopathy, and improve quality of life. This study compared two widely used prognostic tools, the model for end-stage liver disease (MELD) and the Child-Turcotte (C-T) score, in a randomized controlled trial of emergency treatment of bleeding varices. METHODS: We randomized 211 unselected consecutive patients with cirrhosis and bleeding varices to endoscopic sclerotherapy (n = 106) or emergency portacaval shunt (n = 105). Diagnosis and treatment were accomplished within 20 hours. Follow-up was 100% for 10 y. We compared the prognostic powers of MELD and C-T upon entry, and then monthly for the first year and every 3 months thereafter. Statistical analysis included computation of receiver operating curves, the area under the curve, and the proportion of variability. RESULTS: In baseline determinations of MELD versus C-T, there were no significant differences in predicting survival, recurrent encephalopathy, and rebleeding. The Child-Turcotte score was a stronger predictor than MELD of hospital readmissions and readmission days. In serial determinations over years, the prognostic power of both MELD and C-T was substantial, but C-T was significantly more effective in predicting survival and time to recurrent encephalopathy. CONCLUSIONS: In this first long-term comparison of MELD versus C-T in cirrhosis with bleeding varices, C-T was consistently as effective as MELD in predicting survival, encephalopathy, rebleeding, hospital readmissions, and readmission days. In some measures, C-T was a more effective prognostic tool than MELD.

Portal-systemic encephalopathy in a randomized controlled trial of endoscopic sclerotherapy versus emergency portacaval shunt treatment of acutely bleeding esophageal varices in cirrhosis.

BACKGROUND: In patients with cirrhosis and bleeding esophageal varices, there is a widespread belief that control of bleeding by portal-systemic shunts is compromised by a high incidence of shunt-related portal-systemic encephalopathy (PSE). This important issue was examined by a randomized controlled trial that compared emergency and long-term endoscopic sclerotherapy (EST) to emergency direct portacaval shunt (EPCS) in patients with cirrhosis and acute variceal hemorrhage. METHODS: The study was a community-wide undertaking known as the San Diego Bleeding Esophageal Varices Study. A total of 211 unselected, consecutive patients with biopsy-proven cirrhosis and endoscopically proven, acutely bleeding esophageal varices that required at least 2 units of blood transfusion were randomized to EST (n = 106) or EPCS (n = 105). The diagnostic workup was completed in less than 6 hours and EST or EPCS was initiated within 8 hours of initial contact. Long-term EST was performed according to a deliberate schedule over months. Criteria for failure of EST or EPCS were clearly defined and crossover rescue treatment was applied, whenever possible, when failure of primary therapy was declared. PSE was quantitated by a "blinded" senior faculty gastroenterologist. Four variously weighted components of PSE were graded on a scale of 0 to 4: (1) mental state, (2) asterixis, (3) number connection test, and (4) arterial blood ammonia. PSE was classified as recurrent if 2 or more episodes were documented. All patients (100%) had follow-up for more than 9.4 years or until death. RESULTS: Child's risk classes in the EST and EPCS groups, respectively, were 25% and 30% in class A, 43% and 47% in class B, and 26% and 29% in class C. Mean time from onset of bleeding to EST or EPCS was less than 24 hours, and from study entry to EST or EPCS was 3.1 to 4.4 hours, respectively. EST achieved permanent control of bleeding in only 20% of patients, while EPCS permanently controlled bleeding in every patient (P ≤ 0.001). Survival following EPCS was 3.5 to 5 times greater than that of EST at 5, 10, and 15 years (P ≤ 0.001). The incidence of recurrent PSE following EST (35%) was more than twice the incidence following EPCS (15%) (P ≤ 0.001). EST patients had a total of 179 episodes of PSE and 146 PSE-related hospital admissions, compared with EPCS patients who had 94 episodes of PSE and 87 hospital admissions (P ≤ 0.001). Recurrent upper gastrointestinal bleeding, which was rare in the EPCS group, was a major causative factor of PSE in the EST patients. CONCLUSIONS: In contrast to EST, EPCS permanently controlled variceal bleeding, resulted in significantly greater long-term survival, and was followed by a relatively low (15%) incidence of PSE. These results were facilitated by rigorous, frequent, and lifelong follow-up that included regular counseling on dietary protein restriction and abstinence from alcohol, and by long-term patency of the portacaval shunt in 98% of patients. Furthermore, these results call into question the practice of avoiding portacaval shunt because of fear of PSE, and thereby foregoing the lifesaving advantage achieved by surgical control of bleeding. (clinicaltrials.gov NCT00690027).

Randomized trials of endoscopic therapy and transjugular intrahepatic portosystemic shunt versus portacaval shunt for emergency and elective treatment of bleeding gastric varices in cirrhosis.

IMPORTANCE: Bleeding esophageal varices has been studied extensively, but bleeding gastric varices (BGV) has received much less investigation. However, BGV has been reported in ≤ 30% of patients with acute variceal bleeding. In our studies of 1,836 bleeding cirrhotics, 12.7% were bleeding from gastric varices. BGV mortality rate of 45-55% has been reported. The BGV literature has mainly involved retrospective case reports, often with short-term follow-up. OBJECTIVE: We sought to describe the results of a prospective, randomized, controlled trial (RCT) in unselected, consecutive patients with BGV comparing endoscopic therapy (ET) with portacaval shunt (PCS; n = 518), and later comparing emergency transjugular intrahepatic portosystemic shunt (TIPS) with emergency portacaval shunt (EPCS; n = 70). DESIGN, SETTING, AND PARTICIPANTS: Initially, our RCT involved 518 patients with BGV comparing ET with direct PCS regarding control of bleeding, mortality rate, and disability. When entry of patients ended, the RCT was expanded to compare emergency TIPS with EPCS (n = 70). This RCT of BGV was separate from our other RCTs of bleeding esophageal varices. INTERVENTIONS: Initially, ET was compared with PCS. In the second part of our RCT, emergency TIPS was compared with emergency PCS (EPCS). MAIN OUTCOME MEASURES: Outcomes were survival, control of bleeding, portal-systemic encephalopathy (PSE), quality of life, and direct costs of care. In the RCT of ET versus PCS, 28 and 30%, respectively, were in Child class C. In the expanded RCT of TIPS versus EPCS, 40 and 41%, respectively, were in Child class C. Permanent control of BGV was achieved in 97-100% of patients treated by emergency or elective PCS, compared with 27-29% by ET. TIPS was even less effective, achieving long-term control of BGV in only 6%. Survival rates after PCS were greater at all time intervals and in all Child classes (P < .001). Repeated episodes of PSE occurred in 50% of TIPS patients, 16-17% treated by ET, and 8-11% treated by PCS. Shunt stenosis or occlusion occurred in 67% of TIPS patients, in contrast with 0-2% of PCS patients. CONCLUSION: These results support the conclusion that PCS is uniformly effective, whereas ET and TIPS are not very effective.

Unshuntable extrahepatic portal hypertension revisited: 43 years' experience with radical esophagogastrectomy treatment of bleeding esophagogastric varices.

BACKGROUND: In 1994, the authors reported their experience with radical esophagogastrectomy for bleeding esophagogastric varices due to unshuntable extra-hepatic portal hypertension. Since then, the series has expanded from 22 to 44 patients. The aim of this study was to assess the validity of the previous observations and conclusions in the largest series with the longest follow-up. METHODS: From 1968 to 2005, 44 patients with unshuntable extra-hepatic portal hypertension were treated by total gastrectomy and resection of the distal two thirds of the esophagus. Before referral, the patients experienced 4 to 24 episodes of variceal bleeding requiring a mean 130 U of blood transfusion, 15 hospital admissions, and 6 previous unsuccessful operations. RESULTS: Transient postoperative complications occurred in 50% of patients. The survival rate is 100%, with no recurrence of variceal bleeding during 7 to 43 years of follow-up. Liver function and biopsy results have been normal. Quality of life has been excellent or good in 91%. Eighty-six percent have resumed employment or full-time housekeeping. CONCLUSIONS: In unshuntable extra-hepatic portal hypertension, radical esophagogastrectomy is the only consistently effective treatment of variceal hemorrhage. Prompt use of this lifesaving procedure is warranted.

Budd-Chiari syndrome revisited: 38 years' experience with surgical portal decompression.

OBJECTIVE: Ten years ago, we reported our results with what remains as the largest clinical experience with surgical portal decompression for Budd-Chiari syndrome (BCS) in the West. Since then, our series has expanded to 77 patients, and there has been an explosion of interest in and publications about BCS. The objectives of this study are to assess the validity of our observations and conclusions regarding BCS reported 10 years ago by expansion of our series of patients and observations of outcomes over an additional decade of close follow-up. METHODS: Seventy-seven patients with BCS were allocated to three groups: group I, 39 had hepatic vein occlusion alone, treated by side-to-side portacaval shunt (SSPCS); group II, 26 had inferior vena cava occlusion treated by mesoatrial shunt in eight and combined SSPCS and cavoatrial shunt (CAS) in 18; and group III, 12 had decompensated cirrhosis too late for portal decompression who were listed for liver transplantation (LT). An extensive diagnostic workup included angiography with pressure measurements and needle liver biopsy. Follow-up was 100%, lasting 5-38 years. RESULTS: In group I, long-term survival is 95% with 36 free of ascites, leading lives of good quality 5-38 years post-SSPCS. In group II, mesoatrial shunt was discontinued after 1990 because of a high failure rate, but combined SSPCS-CAS has resulted in 100% survival for 5-25 years. In group III, six patients (50%) are alive and well for more than 5 years post-LT. Serial liver biopsies following portal decompression have shown long-term reversal of the lesions of BCS. CONCLUSIONS: Long-term survival following portal decompression of BCS in the West has not been equaled by any other form of therapy, medical or surgical. It is imperative to perform surgical portal decompression early in the course of BCS in order to avoid irreversible liver damage.

Randomized controlled trial of emergency transjugular intrahepatic portosystemic shunt versus emergency portacaval shunt treatment of acute bleeding esophageal varices in cirrhosis.

BACKGROUND: Emergency treatment of bleeding esophageal varices (BEV) in cirrhosis is of paramount importance because of the resultant high mortality rate. Emergency therapy today consists mainly of endoscopic and pharmacologic measures, with use of transjugular intrahepatic portosystemic shunt (TIPS) when bleeding is not controlled. Surgical portosystemic shunt has been relegated to last resort salvage when all other measures fail. Regrettably, no randomized controlled trials have been reported in which TIPS and surgical portosystemic shunt were compared in unselected patients with acute BEV, with long-term follow-up. This is a report of a long-term prospective randomized controlled trial (RCT) that compared TIPS with emergency portacaval shunt (EPCS) in patients with cirrhosis and acute BEV. STUDY DESIGN: A total of 154 unselected, consecutive cirrhotic patients ("all comers") with acute BEV were randomized to TIPS (n = 78) or EPCS (n = 76), and the two treatments were compared with regard to effect on survival, control of bleeding, portal-systemic encephalopathy (PSE), and disability. Diagnostic workup was completed within 6 h and TIPS or EPCS was initiated within 24 h. Regular follow-up was accomplished in 100 % of patients and lasted for 5 to 10 years in 85 % and 3 to 4.5 years in the remainder. This report focuses on control of bleeding and survival. RESULTS: The clinical characteristics of the two groups were similar, and the distribution of Child classes A, B, and C was almost identical. TIPS was successful in controlling BEV for 30 days in 80 % of patients but achieved long-term control of BEV in only 22 %. In contrast, EPCS controlled BEV immediately in all patients and permanently in 97 % (p < 0.001). TIPS patients required almost twice as many units of blood transfusion as EPCS patients. Survival rate at all time intervals and in all Child classes was significantly greater following EPCS than after TIPS (p < 0.001). Median survival was over 10 years following EPCS, compared to 1.99 years following TIPS. Stenosis or occlusion of TIPS was demonstrated in 84 % of patients who survived 21 days, 63 % of whom underwent TIPS revision, which failed in 80 %. In contrast, EPCS remained permanently patent in 97 % of patients. Recurrent PSE was threefold more frequent following TIPS than after EPCS (61 versus 21 %). CONCLUSIONS: EPCS was uniformly effective in the treatment of BEV, while TIPS was disappointing. EPCS accomplished long-term survival while TIPS resulted in a survival rate that was less than one fifth that of EPCS. The results of this RCT in unselected, consecutive patients justify the use of EPCS as a first-line emergency treatment of BEV in cirrhosis (clinicaltrials.gov #NCT00734227).

A randomized controlled trial of emergency treatment of bleeding esophageal varices in cirrhosis for hepatocellular carcinoma.

BACKGROUND: Ninety percent of patients with hepatocellular carcinoma (HCC) have cirrhosis. Bleeding esophageal varices (BEV) is a frequent complication of cirrhosis. Detection of HCC in cirrhotic patients with BEV has not been studied. METHODS: Two hundred eleven unselected patients with cirrhosis and BEV were randomized to endoscopic sclerotherapy (n = 106) or emergency portacaval shunt (n = 105). Diagnostic workup and treatment were initiated within 8 hours. Ninety-six percent had >10 years of follow-up. HCC screening involved serum α-fetoprotein (AFP) every 3 months, ultrasonography every 6 months, and selective computed tomography (CT). RESULTS: HCC occurred in 15 patients, all incurable, a mean of 2.94 years after entry. They died a mean 1.33 years after discovery. Serial AFP and ultrasound examinations were unrevealing over a mean of 2.3 years. The mean model of end-stage liver disease score was 12.7 at entry and 17.4 at HCC diagnosis. CONCLUSIONS: Long-term screening by AFP and ultrasound plus selective CT failed to detect HCC at a curable stage. The detection of HCC in cirrhotic patients with BEV remains a serious, unsolved problem. The use of CT for routine screening warrants consideration despite increased costs.

Disability index in a randomized controlled trial of emergency sclerotherapy versus portacaval shunt for bleeding varices in cirrhosis.

BACKGROUND: Disability has not been studied after emergency treatment of bleeding esophageal varices (BEV). We created a disability index (DI) in a randomized controlled trial comparing emergency endoscopic therapy (EST) versus emergency portacaval shunt (EPCS). METHODS: There were 211 unselected, consecutive patients with cirrhosis and acute BEV who were randomized to EST (n = 106) or EPCS (n = 105). Diagnostic work-up and treatment were performed within 8 hours. Ninety-six percent underwent more than 10 years follow-up evaluation. Disability was measured by assessing 9 factors to create a DI. RESULTS: Ten-year survival was 8% after EST versus 51% after EPCS (P < .001). EPCS had a significantly better DI. The EST and EPCS values were as follows: liver function improvement: not applicable and ++; worsening liver function, ++ and not applicable; portal-systemic encephalopathy (PSE) incidence, 36 and 15; PSE episodes, 179 and 94; packed red blood cell units, 1,005 and 320; hospital readmissions, 387 and 292; and number of readmission days, 9.6 and 4.7. All of the P values were less than .001. CONCLUSIONS: EPCS resulted in a markedly better DI than EST, a significantly higher survival rate, better control of bleeding, and a lower incidence of PSE. EPCS is an effective first-line emergency treatment of BEV.

Direct costs of care in a randomized controlled trial of endoscopic sclerotherapy versus emergency portacaval shunt for bleeding esophageal varices in cirrhosis--Part 4.

BACKGROUND: Emergency treatment of bleeding esophageal varices (BEV) in cirrhotic patients is of prime importance because of the high mortality rate surrounding the episode of acute bleeding. Nevertheless, there is a paucity of randomized controlled trials of emergency surgical therapy and no reports of the costs of any of the widely used forms of emergency treatment. The important issue of direct costs of care was examined in a randomized controlled trial that compared endoscopic sclerotherapy (EST) to emergency portacaval shunt (EPCS). METHODS: Two hundred eleven unselected consecutive patients with ultimately biopsy-proven cirrhosis and endoscopically proven acute BEV were randomized to EST (n = 106) or EPCS (n = 105). Diagnostic workup was completed, and EST or EPCS was initiated within 8 h. Criteria for failure of EST or EPCS were clearly defined, and crossover rescue treatment was applied, when primary therapy failed. Ninety-six percent of patients underwent more than 10 years follow-up, or until death. Complete charges for all aspects of care were obtained continuously for more than 10 years. RESULTS: Direct charges for all aspects of care were significantly lower in patients treated by EPCS than in patients treated by emergency EST followed by long-term repetitive sclerotherapy. Charges per patient, per year of treatment, and per year in each child's risk class were significantly lower in patients randomized to EPCS. Charges in patients who failed endoscopic sclerotherapy and underwent a rescue portacaval shunt were significantly higher than the charges in both the unshunted sclerotherapy patients and the patients randomized to EPCS. This result was particularly noteworthy given the widespread practice of using surgical portacaval shunt as rescue treatment only when all other forms of therapy have failed. CONCLUSIONS: In this randomized controlled trial of emergency treatment of acute BEV, EPCS was significantly superior to EST with regard to direct costs of care as reflected in charges for care as well as in survival rate, control of bleeding, and incidence of portal-systemic encephalopathy. These results provide support for the use of EPCS as a first line of emergency treatment of BEV in cirrhosis.

Emergency portacaval shunt versus rescue portacaval shunt in a randomized controlled trial of emergency treatment of acutely bleeding esophageal varices in cirrhosis--part 3.

BACKGROUND: Emergency treatment of bleeding esophageal varices in cirrhosis is of singular importance because of the high mortality rate. Emergency portacaval shunt is rarely used today because of the belief, unsubstantiated by long-term randomized trials, that it causes frequent portal-systemic encephalopathy and liver failure. Consequently, portacaval shunt has been relegated solely to salvage therapy when endoscopic and pharmacologic therapies have failed. QUESTION: Is the regimen of endoscopic sclerotherapy with rescue portacaval shunt for failure to control bleeding varices superior to emergency portacaval shunt? A unique opportunity to answer this question was provided by a randomized controlled trial of endoscopic sclerotherapy versus emergency portacaval shunt conducted from 1988 to 2005. METHODS: Unselected consecutive cirrhotic patients with acute bleeding esophageal varices were randomized to endoscopic sclerotherapy (n = 106) or emergency portacaval shunt (n = 105). Diagnostic workup was completed and treatment was initiated within 8 h. Failure of endoscopic sclerotherapy was defined by strict criteria and treated by rescue portacaval shunt (n = 50) whenever possible. Ninety-six percent of patients had more than 10 years of follow-up or until death. RESULTS: Comparison of emergency portacaval shunt and endoscopic sclerotherapy followed by rescue portacaval shunt showed the following differences in measurements of outcomes: (1) survival after 5 years (72% versus 22%), 10 years (46% versus 16%), and 15 years (46% versus 0%); (2) median post-shunt survival (6.18 versus 1.99 years); (3) mean requirements of packed red blood cell units (17.85 versus 27.80); (4) incidence of recurrent portal-systemic encephalopathy (15% versus 43%); (5) 5-year change in Child's class showing improvement (59% versus 19%) or worsening (8% versus 44%); (6) mean quality of life points in which lower is better (13.89 versus 27.89); and (7) mean cost of care per year ($39,200 versus $216,700). These differences were highly significant in favor of emergency portacaval shunt (all p < 0.001). CONCLUSIONS: Emergency portacaval shunt was strikingly superior to endoscopic sclerotherapy as well as to the combination of endoscopic sclerotherapy and rescue portacaval shunt in regard to all outcome measures, specifically bleeding control, survival, incidence of portal-systemic encephalopathy, improvement in liver function, quality of life, and cost of care. These results strongly support the use of emergency portacaval shunt as the first line of emergency treatment of bleeding esophageal varices in cirrhosis.

Randomized trial of emergency endoscopic sclerotherapy versus emergency portacaval shunt for acutely bleeding esophageal varices in cirrhosis.

BACKGROUND: The mortality rate of bleeding esophageal varices in cirrhosis is highest during the period of acute bleeding. This is a report of a randomized trial that compared endoscopic sclerotherapy (EST) with emergency portacaval shunt (EPCS) in cirrhotic patients with acute variceal hemorrhage. STUDY DESIGN: A total of 211 unselected consecutive patients with cirrhosis and acutely bleeding esophageal varices who required at least 2 U of blood transfusion were randomized to EST (n=106) or EPCS (n=105). Diagnostic workup was completed within 6 hours and EST or EPCS was initiated within 8 hours of initial contact. Longterm EST was performed according to a deliberate schedule. Ninety-six percent of patients underwent more than 10 years of followup, or until death. RESULTS: The percent of patients in Child's risk classes were A, 27.5; B, 45.0; and C, 27.5. EST achieved permanent control of bleeding in only 20% of patients; EPCS permanently controlled bleeding in every patient (p< or =0.001). Requirement for blood transfusions was greater in the EST group than in the EPCS patients. Compared with EST, survival after EPCS was significantly higher at all time intervals and in all Child's classes (p< or =0.001). Recurrent episodes of portal-systemic encephalopathy developed in 35% of EST patients and 15% of EPCS patients (p< or =0.01). CONCLUSIONS: EPCS permanently stopped variceal bleeding, rarely became occluded, was accomplished with a low incidence of portal-systemic encephalopathy, and compared with EST, produced greater longterm survival. The widespread practice of using surgical procedures mainly as salvage for failure of endoscopic therapy is not supported by the results of this trial (clinicaltrials.gov #NCT00690027).

Heat-stable enterotoxin of Escherichia coli stimulates a non-CFTR-mediated duodenal bicarbonate secretory pathway.

The cystic fibrosis (CF) transmembrane conductance regulator (CFTR) is an important pathway for duodenal mucosal bicarbonate secretion. Duodenal biopsies from CF patients secrete bicarbonate in response to heat-stable enterotoxin from Escherichia coli (STa) but not cAMP. To explore the mechanism of STa-induced bicarbonate secretion in CF more fully, we examined the role of CFTR in STa-stimulated duodenal bicarbonate secretion in mice. In vivo, the duodenum of CFTR (-/-) or control mice was perfused with forskolin (10(-4) M), STa (10(-7) M), uroguanylin (10(-7) M), 8-bromoguanosine 3',5'-cGMP (8-Br-cGMP) (10(-3) M), genistein (10(-6) M) plus STa, or herbimycin A (10(-6) M) plus STa. In vitro, duodenal mucosae were voltage-clamped in Ussing chambers, and bicarbonate secretion was measured by pH-stat. The effect of genistein, DIDS (10(-4) M), and chloride removal was also studied in vitro. Control, but not CF, mice produced a significant increase in duodenal bicarbonate secretion after perfusion with forskolin, uroguanylin, or 8-Br-cGMP. However, both control and CF animals responded to STa with significant increases in bicarbonate output. Genistein and herbimycin A abolished this response in CF mice but not in controls. In vitro, STa-stimulated bicarbonate secretion in CF tissues was inhibited by genistein, DIDS, and chloride-free conditions, whereas bicarbonate secretion persisted in control mice. In the CF duodenum, STa can stimulate bicarbonate secretion via tyrosine kinase activity resulting in apical Cl(-)/HCO(3)(-) exchange. Further studies elucidating the intracellular mechanisms responsible for such non-CFTR mediated bicarbonate secretion may lead to important therapies for CF.

Effect of 5-hydroxytryptamine on duodenal mucosal bicarbonate secretion in mice.

BACKGROUND & AIMS: 5-hydroxytryptamine (5-HT) is an important neurotransmitter and intercellular messenger that modulates many gastrointestinal functions. Because little is known about the role of 5-HT in the regulation of duodenal bicarbonate secretion, we examined the role of 5-HT on duodenal bicarbonate secretion and define neural pathways involved in the actions of 5-HT. METHODS: Duodenal mucosa from National Institutes of Health Swiss mice was stripped of seromuscular layers and mounted in Ussing chambers. The effect of 5-HT on duodenal bicarbonate secretion was determined by the pH stat technique. Acetylcholine (ACh) release from duodenal mucosa was assessed by preincubating the tissue with [(3)H] choline and measuring 5-HT-evoked release of tritium. RESULTS: 5-HT added to the serosal bath markedly stimulated duodenal bicarbonate secretion and short circuit current (Isc) in a dose-dependent manner (10(-7) mol/L to 10(-3) mol/L; P < 0.0001), whereas mucosally added 5-HT was without effect. 5-HT-stimulated bicarbonate secretion was independent of luminal Cl(-). Pretreatment with tetrodotoxin (TTX) (10(-6) mol/L) or atropine (10(-5) mol/L) markedly reduced 5-HT-stimulated duodenal bicarbonate secretion (by 60% and 65%, respectively; P < 0.001) and Isc (by 45% and 27%, respectively; P < 0.001 and P < 0.05). Pretreatment with N(omega)-nitro-l-arginine methyl ester (l-NAME) (10(-3) mol/L), propranolol (10(-5) mol/L), or phentolamine (10(-5) mol/L) did not significantly alter 5-HT-stimulated duodenal mucosal bicarbonate secretion or Isc. 5-HT concentration-dependently evoked ACh release from duodenal mucosal preparations (P < 0.0001). TTX markedly inhibited 5-HT-evoked ACh release (P < 0.001). CONCLUSIONS: 5-HT is a potent activator of duodenal mucosal bicarbonate secretion in mice. Duodenal bicarbonate secretion induced by 5-HT in vitro occurs principally via a cholinergic neural pathway.

Protein kinase C potentiates cAMP-stimulated mouse duodenal mucosal bicarbonate secretion in vitro.

PKC has been shown to regulate epithelial Cl(-) secretion in a variety of models. However, the role of PKC in duodenal mucosal bicarbonate secretion is less clear. We aimed to investigate the role of PKC in regulation of duodenal mucosal bicarbonate secretion. Bicarbonate secretion by murine duodenal mucosa was examined in vitro in Ussing chambers using a pH-stat technique. PKC isoform expression and activity were assessed by Western blotting and in vitro kinase assays, respectively. PMA (an activator of PKC) alone had no effect on duodenal bicarbonate secretion or short-circuit current (I(sc)). When PMA and dibutyryl-cAMP (db-cAMP) were added simultaneously, PMA failed to alter db-cAMP-stimulated duodenal bicarbonate secretion or I(sc) (P > 0.05). However, a 1-h preincubation with PMA potentiated db-cAMP-stimulated duodenal bicarbonate secretion and I(sc) in a concentration-dependent manner (from 10(-8) to 10(-5)M) (P < 0.05). PMA preincubation had no effects on carbachol- or heat-stable toxin-stimulated bicarbonate secretion. Western blot analysis revealed that PKCalpha, -gamma, -epsilon, -, -micro, and -iota/lambda were expressed in murine duodenal mucosa. Ro 31-8220 (an inhibitor active against PKCepsilon, -alpha, -beta, and -gamma), but not Gö 6983 (an inhibitor active against PKCalpha, -gamma, -beta, and -delta), reversed the potentiating effect of PMA on db-cAMP-stimulated bicarbonate secretion. PMA also time- and concentration-dependently increased the activity of PKCepsilon, an effect that was prevented by Ro 31-8220 but not Gö 6983. These results demonstrate that activation of PKC potentiates cAMP-stimulated duodenal bicarbonate secretion, whereas it does not modify basal secretion. The effect of PKC on cAMP-stimulated bicarbonate secretion is mediated by the PKCepsilon isoform.

5-HT induces duodenal mucosal bicarbonate secretion via cAMP- and Ca2+-dependent signaling pathways and 5-HT4 receptors in mice.

In previous studies, we have found that 5-hydroxytryptamine (5-HT) is a potent stimulant of duodenal mucosal bicarbonate secretion (DMBS) in mice. The aim of the present study was to determine the intracellular signaling pathways and 5-HT receptor subtypes involved in 5-HT-induced DMBS. Bicarbonate secretion by murine duodenal mucosa was examined in vitro in Ussing chambers. 5-HT receptor involvement in DMBS was inferred from pharmacological studies by using selective 5-HT receptor antagonists and agonists. The expression of 5-HT(4) receptor mRNA in duodenal mucosa and epithelial cells was analyzed by RT-PCR. cAMP-dependent signaling pathway inhibitors MDL-12330A, Rp-cAMP, and H-89 and Ca(2+)-dependent signaling pathway inhibitors verapamil and W-13 markedly reduced 5-HT-stimulated duodenal bicarbonate secretion and short-circuit current (I(sc)), whereas cGMP-dependent signaling pathway inhibitors NS-2028 and KT-5823 failed to alter these responses. Both SB-204070 and high-dose ICS-205930 (selective 5-HT(4) receptor antagonists) markedly inhibited 5-HT-stimulated bicarbonate secretion and I(sc), whereas methiothepine (5-HT(1) receptor antagonist), ketanserin (5-HT(2) receptor antagonist), and a low concentration of ICS-205930 (5-HT(3) receptor antagonist) had no effect. RS-67506 (partial 5-HT(4) receptor agonist) concentration-dependently increased bicarbonate secretion and I(sc), whereas 5-carboxamidotryptamine (5-HT(1) receptor agonist), alpha-methyl-5-HT (5-HT(2) receptor agonist), and phenylbiguanide (5-HT(3) receptor agonist) did not significantly increase bicarbonate secretion or I(sc). RT-PCR analysis confirmed the expression of 5-HT(4) receptor mRNA in murine duodenal mucosa and epithelial cells. These results demonstrate that 5-HT regulates DMBS via both cAMP- and Ca(2+)-dependent signaling pathways and 5-HT(4) receptors located in the duodenal mucosa and/or epithelial cells.

A role for CagA/VacA in Helicobacter pylori inhibition of murine duodenal mucosal bicarbonate secretion.

Duodenal mucosal bicarbonate secretion is diminished in patients with Helicobacter pylori (HP)-associated duodenal ulcer disease. We examined whether HP water extracts inhibit murine duodenal mucosal bicarbonate secretion in vitro, and the mechanisms involved. Murine duodenal mucosae were mounted in Ussing chambers. Short-circuit current and bicarbonate secretion was measured. CagA/VacA-positive HP water extract (HPWE+/+) markedly inhibited PGE2-, carbachol-, or the calcium ionophore A23187-stimulated bicarbonate secretion in a dose-dependent manner. While 3-isobutyl-1-methylxanthine-stimulated bicarbonate secretion was not affected by HPWE+/+, HPWE+/+ did diminish forskolin-stimulated bicarbonate secretion. HPWE+/+ markedly diminished PGE2-induced increases in duodenal mucosal cAMP. CagA/VacA of HP decreases Ca2+-mediated bicarbonate secretion downstream of increases in intracellular Ca2+. Dimunition of PGE2-stimulated bicarbonate secretion occurs, in part, by inhibition of adenylate cyclase, which leads to decreased cAMP levels. The ability of virulent HP strains to inhibit duodenal bicarbonate secretion through multiple intracellular pathways likely contributes to the pathogenesis of HP-associated duodenal ulcer disease.