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ObjectivesAbdominal pain, emergency department visits, and hospitalizations impact lives of children with acute recurrent pancreatitis (ARP) and chronic pancreatitis (CP). Data on health-related quality of life (HRQOL) in this population, however, remains limited. We aimed to evaluate HRQOL in children with ARP or CP; and test biopsychosocial risk factors associated with low HRQOL.MethodsData were acquired from the INternational Study Group of Pediatric Pancreatitis: In search for a cuRE registry. Baseline demographic and clinical questionnaires, the Child Health Questionnaire (measures HRQOL) and Child Behavior Checklist (measures emotional and behavioral functioning) were completed at enrollment.ResultsThe sample included 368 children (54.3% girls, mean age = 12.7years, standard deviation [SD] = 3.3); 65.2% had ARP and 34.8% with CP. Low physical HRQOL (M = 38.5, SD = 16.0) was demonstrated while psychosocial HRQOL (M = 49.5, SD = 10.2) was in the normative range. Multivariate regression analysis revealed that clinical levels of emotional and behavioral problems (B = -10.28, P

ObjectiveThe aim of the study was to determine whether clinical characteristics and management of pediatric acute recurrent pancreatitis (ARP) and chronic pancreatitis (CP) differ across INSPPIRE (INternational Study Group of Pediatric Pancreatitis: In Search for a cuRE) sites.Study designData were collected from INSPPIRE and analyzed per US regions and "non-US" sites. Between-group differences were compared by Pearson chi-square test. Differences in disease burden were compared by Kruskal-Wallis test.ResultsOut of the 479 subjects, 121 (25%) were enrolled in West, 151 (32%) Midwest, 45 Northeast (9%), 78 (16%) South, and 84 (18%) at non-US sites. Hispanic ethnicity was more common in South (P

ObjectivesThe aim of the study was to understand the association of frequent opioid use with disease phenotype and pain pattern and burden in children and adolescents with acute recurrent (ARP) or chronic pancreatitis (CP).MethodsCross-sectional study of children

IntroductionAbdominal pain is common and is associated with high disease burden and health care costs in pediatric acute recurrent and chronic pancreatitis (ARP/CP). Despite the strong central component of pain in ARP/CP and the efficacy of psychological therapies for other centralized pain syndromes, no studies have evaluated psychological pain interventions in children with ARP/CP. The current trial seeks to 1) evaluate the efficacy of a psychological pain intervention for pediatric ARP/CP, and 2) examine baseline patient-specific genetic, clinical, and psychosocial characteristics that may predict or moderate treatment response.MethodsThis single-blinded randomized placebo-controlled multicenter trial aims to enroll 260 youth (ages 10-18) with ARP/CP and their parents from twenty-one INSPPIRE (INternational Study Group of Pediatric Pancreatitis: In search for a cuRE) centers. Participants will be randomly assigned to either a web-based cognitive behavioral pain management intervention (Web-based Management of Adolescent Pain Chronic Pancreatitis; WebMAP; N = 130) or to a web-based pain education program (WebED; N = 130). Assessments will be completed at baseline (T1), immediately after completion of the intervention (T2) and at 6 months post-intervention (T3). The primary study outcome is abdominal pain severity. Secondary outcomes include pain-related disability, pain interference, health-related quality of life, emotional distress, impact of pain, opioid use, and healthcare utilization.ConclusionsThis is the first clinical trial to evaluate the efficacy of a psychological pain intervention for children with CP for reduction of abdominal pain and improvement of health-related quality of life. Findings will inform delivery of web-based pain management and potentially identify patient-specific biological and psychosocial factors associated with favorable response to therapy. Clinical Trial Registration #: NCT03707431.

OBJECTIVES:Adults with chronic pancreatitis (CP) have a high risk for developing pancreatogenic diabetes mellitus (DM), but little is known regarding potential risk factors for DM in children with acute recurrent pancreatitis (ARP) or CP. We compared demographic and clinical features of children with ARP or CP, with and without DM, in the INternational Study Group of Pediatric Pancreatitis: In Search of a CuRE (INSPPIRE) registry. METHODS:We reviewed the INSPPIRE database for the presence or absence of physician-diagnosed DM in 397 children, excluding those with total pancreatectomy with islet autotransplantation, enrolled from August 2012 to August 2017. Patient demographics, body mass index percentile, age at disease onset, disease risk factors, disease burden, and treatments were compared between children with DM (n = 24) and without DM (n = 373). RESULTS:24 children (6.0% of the cohort) had a diagnosis of DM. Five of 13 tested were positive for beta cell autoantibodies. The DM group was 4.2 years (95% CI 3.0, 5.4) older at first episode of acute pancreatitis, and tended to more often have hypertriglyceridemia (odds ratio (OR) 5.21 (1.33, 17.05)), coexisting autoimmune disease (OR 3.94 (0.88, 13.65)) or pancreatic atrophy (OR 3.64 (1.13, 11.59)). CONCLUSIONS:Pancreatic atrophy may be more common among children with DM, suggesting more advanced exocrine disease. However, data in this exploratory cohort also suggest increased autoimmunity and hypertriglyceridemia in children with DM, suggesting that risk factors for Type 1 and Type 2 DM respectively may play a role in mediating DM development in children with pancreatitis.

ObjectiveThe aim of the study was to determine the rate of progression from acute recurrent pancreatitis (ARP) to chronic pancreatitis (CP) in children and assess risk factors.Study designData were collected from the INternational Study group of Pediatric Pancreatitis: In search for a cuRE (INSPPIRE) cohort. Kaplan-Meier curves were constructed to calculate duration of progression from initial attack of acute pancreatitis (AP) to CP. Log-rank test was used to compare survival (nonprogression) probability distribution between groups. Cox proportional hazard regression models were fitted to obtain hazard ratio (with 95% confidence interval [CI]) of progression for each risk variable.ResultsOf 442 children, 251 had ARP and 191 had CP. The median time of progression from initial attack of AP to CP was 3.79 years. The progression was faster in those ages 6 years or older at the first episode of AP compared to those younger than 6 years (median time to CP: 2.91 vs 4.92 years; P = 0.01). Children with pathogenic PRSS1 variants progressed more rapidly to CP compared to children without PRSS1 variants (median time to CP: 2.52 vs 4.48 years; P = 0.003). Within 6 years after the initial AP attack, cumulative proportion with exocrine pancreatic insufficiency was 18.0% (95% CI: 12.4%, 25.6%); diabetes mellitus was 7.7% (95% CI: 4.2%, 14.1%).ConclusionsChildren with ARP rapidly progress to CP, exocrine pancreatic insufficiency, and diabetes. The progression to CP is faster in children who were 6 years or older at the first episode of AP or with pathogenic PRSS1 variants. The factors that affect the aggressive disease course in childhood warrant further investigation.

IntroductionThe significance of pancreas divisum (PD) as a risk factor for pancreatitis is controversial. We analyzed the characteristics of children with PD associated with acute recurrent or chronic pancreatitis to better understand its impact.Patients and methodsWe compared children with or without PD in the well-phenotyped INSPPIRE (INternational Study group of Pediatric Pancreatitis: In search for a cuRE) cohort. Differences were analyzed using 2-sample t test or Wilcoxon rank sum test for continuous variables, Pearson χ or Fisher exact test for categorical variables.ResultsPD was found in 52 of 359 (14.5%) subjects, a higher prevalence than the general population (∼7%). Females more commonly had PD (71% vs. 55%; P=0.02). Children with PD did not have a higher incidence of mutations in SPINK1, CFTR, CTRC compared with children with no PD. Children with PD were less likely to have PRSS1 mutations (10% vs. 34%; P

ObjectivesThe aim of the present study was to investigate the natural history of chronic pancreatitis (CP); patients in the North American Pancreatitis Study2 (NAPS2, adults) and INternational Study group of Pediatric Pancreatitis: In search for a cuRE (INSPPIRE, pediatric) were compared.MethodsDemographics, risk factors, disease duration, management and outcomes of 224 children and 1063 adults were compared using appropriate statistical tests for categorical and continuous variables.ResultsAlcohol was a risk in 53% of adults and 1% of children (P

We created the INternational Study Group of Pediatric Pancreatitis: In Search for a CuRE (INSPPIRE 2) cohort to study the risk factors, natural history, and outcomes of pediatric acute recurrent pancreatitis and chronic pancreatitis (CP). Patient and physician questionnaires collect information on demographics, clinical history, family and social history, and disease outcomes. Health-related quality of life, depression, and anxiety are measured using validated questionnaires. Information entered on paper questionnaires is transferred into a database managed by Consortium for the Study of Chronic Pancreatitis, Diabetes, and Pancreatic Cancer's Coordinating and Data Management Center. Biosamples are collected for DNA isolation and analysis of most common pancreatitis-associated genes.Twenty-two sites (18 in the United States, 2 in Canada, and 1 each in Israel and Australia) are participating in the INSPPIRE 2 study. These sites have enrolled 211 subjects into the INSPPIRE 2 database toward our goal to recruit more than 800 patients in 2 years. The INSPPIRE 2 cohort study is an extension of the INSPPIRE cohort study with a larger and more diverse patient population. Our goals have expanded to include evaluating risk factors for CP, its sequelae, and psychosocial factors associated with pediatric acute recurrent pancreatitis and CP.

ObjectiveThe aim of this study was to assess the impact of obesity on pediatric acute recurrent pancreatitis or chronic pancreatitis (CP).MethodsWe determined body mass index (BMI) status at enrollment in INSPPIRE (INternational Study group of Pediatric Pancreatitis: In search for a cuRE) cohort using CDC criteria for pediatric-specific BMI percentiles. We used the Cochran-Armitage test to assess trends and the Jonckheere-Terpstra test to determine associations.ResultsOf 446 subjects (acute recurrent pancreatitis, n = 241; CP, n = 205), 22 were underweight, 258 normal weight, 75 overweight, and 91 were obese. The BMI groups were similar in sex, race, and age at presentation. Hypertriglyceridemia was more common in overweight or obese. Obese children were less likely to have CP and more likely to have acute inflammation on imaging. Compared with children with normal weight, obese or overweight children were older at first acute pancreatitis episode and diagnosed with CP at an older age. Obese or overweight children were less likely to undergo medical or endoscopic treatment, develop exocrine pancreatic insufficiency, and require total pancreatectomy with islet autotransplantation. Diabetes was similar among all groups.ConclusionsObesity or overweight seems to delay the initial acute pancreatitis episode and diagnosis of CP compared with normal weight or underweight. The impact of obesity on pediatric CP progression and severity deserves further study.

OBJECTIVES:Autoimmune pancreatitis (AIP) represents a complex immune-mediated pancreas disorder. Pediatric AIP (P-AIP) is rare. We have recently summarized the characteristic features of P-AIP. We now aim to develop recommendation statements to standardize the diagnostic and therapeutic approach to P-AIP and facilitate future research in the field. METHODS:A panel of pediatric gastroenterologists participating in the International Study Group of Pediatric Pancreatitis: In search for a cuRE was formed to discuss and then vote on 15 recommendation statements. A consensus of at least 80% was obtained following 3 voting rounds and revision of the statements. RESULTS:We have now generated 15 statements to help standardize the approach to diagnosis and management of P-AIP. CONCLUSIONS:The first P-AIP recommendation statements developed by the International Study Group of Pediatric Pancreatitis: In search for a cuRE group are intended to bring standardization to the diagnosis and treatment of this rare childhood disorder. These statements may help guide a uniform approach to patient care and facilitate future research studies.

ObjectivesAutoimmune pancreatitis (AIP) is an increasingly recognized disease entity, but data in children are limited. AIP presentation and outcome in children might differ from the adult experience. We aim to determine the characteristic features of AIP in children.MethodsData about clinical symptoms, imaging, histology, and treatment were collected using two sources: (i) a systematic literature search and (ii) the INSPPIRE database, the largest international multicenter study of pancreatitis in children and the Cliniques Universitaires St-Luc (CUSL) registry.ResultsWe identified 48 AIP cases: 30 from literature review, 14 from INSPPIRE, and 4 from CUSL. The median age at diagnosis was 13 years (range 2-17 years). Abdominal pain (43/47, 91%) and/or obstructive jaundice (20/47, 42%) were the most common symptoms at diagnosis. Elevated serum IgG4 levels were only observed in 9/40 (22%) children. Cross-sectional imaging studies were abnormal in all children including hypointense global or focal gland enlargement (39/47, 83%), main pancreatic duct irregularity (30/47, 64%), and common bile duct stricture (26/47, 55%). A combination of lymphoplasmacytic inflammation, pancreatic fibrosis, and ductal granulocyte infiltration were the main histological findings (18/25, 72%). Children with AIP had a prompt clinical response to steroids. Complications of AIP included failure of exocrine (4/25, 16%) and endocrine (3/27, 11%) pancreas function.ConclusionsPediatric AIP has a distinct presentation with features similar to type 2 AIP in adults. This comprehensive report on the largest group of children with AIP to date is expected to help with the diagnosis and management of this disease and pave the way for future research studies.

ObjectivesTo assess whether the age of onset was associated with unique features or disease course in pediatric acute recurrent pancreatitis (ARP) or chronic pancreatitis (CP).Study designDemographic and clinical information on children with ARP or CP was collected at INSPPIRE (INternational Study Group of Pediatric Pancreatitis: In Search for a CuRE) centers. The Cochran-Armitage trend test and Jonckheere-Terpstra test were used to examine for differences between pediatric age groups (

ObjectiveThe aim of this study was to characterize utilization and benefit of therapeutic endoscopic retrograde cholangiopancreatography (ERCP) in children with acute recurrent pancreatitis (ARP) or chronic pancreatitis (CP).MethodsFrom August 2012 to February 2015, 301 children with ARP or CP were enrolled in the INSPPIRE (INternational Study group of Pediatric Pancreatitis: In search for a cuRE) study. Physicians reported utilization and benefit of therapeutic ERCP at enrollment. Differences were analyzed using appropriate statistical methods.ResultsOne hundred seventeen children (38.9%) underwent at least 1 therapeutic ERCP. The procedure was more commonly performed in children with CP compared with those with ARP (65.8% vs 13.5%, P < 0.0001). Utility of therapeutic ERCP was reported to be similar between ARP and CP (53% vs 56%, P = 0.81) and was found to be helpful for at least 1 indication in both groups (53/99 patients [53.5%]). Predictors for undergoing therapeutic ERCP were presence of obstructive factors in ARP and CP, Hispanic ethnicity, or white race in CP.ConclusionsTherapeutic ERCP is frequently utilized in children with ARP or CP and may offer benefit in selected cases, specifically if ductal obstruction is present. Longitudinal studies are needed to clarify the efficacy of therapeutic ERCP and to explore subgroups that might have increased benefit from such intervention.

ObjectivesAcute recurrent pancreatitis (ARP) and chronic pancreatitis (CP) have been diagnosed in children at increasing rates during the past decade. As pediatric ARP and CP are still relatively rare conditions, little quality evidence is available on which to base the diagnosis and determination of etiology. The aim of the study was to review the current state of the literature regarding the etiology of these disorders and to developed a consensus among a panel of clinically active specialists caring for children with these disorders to help guide the diagnostic evaluation and identify areas most in need of future research.MethodsA systematic review of the literature was performed and scored for quality, followed by consensus statements developed and scored by each individual in the group for level of agreement and strength of the supporting data using a modified Delphi method. Scores were analyzed for the level of consensus achieved by the group.ResultsThe panel reached consensus on 27 statements covering the definitions of pediatric ARP and CP, evaluation for potential etiologies of these disorders, and long-term monitoring. Statements for which the group reached consensus to make no recommendation or could not reach consensus are discussed.ConclusionsThis consensus helps define the minimal diagnostic evaluation and monitoring of children with ARP and CP. Even in areas in which we reached consensus, the quality of the evidence is weak, highlighting the need for further research. Improved understanding of the underlying cause will facilitate treatment development and targeting.

ImportancePediatric acute recurrent pancreatitis (ARP) and chronic pancreatitis (CP) are poorly understood.ObjectiveTo characterize and identify risk factors associated with ARP and CP in childhood.Design, setting, and participantsA multinational cross-sectional study of children with ARP or CP at the time of enrollment to the INSPPIRE (International Study Group of Pediatric Pancreatitis: In Search for a Cure) study at participant institutions of the INSPPIRE Consortium. From August 22, 2012, to February 8, 2015, 155 children with ARP and 146 with CP (aged ≤19 years) were enrolled. Their demographic and clinical information was entered into the REDCap (Research Electronic Data Capture) database at the 15 centers. Differences were analyzed using 2-sample t test or Wilcoxon rank sum test for continuous variables and Pearson χ2 test or Fisher exact test for categorical variables. Disease burden variables (pain variables, hospital/emergency department visits, missed school days) were compared using Wilcoxon rank sum test.Main outcomes and measuresDemographic characteristics, risk factors, abdominal pain, and disease burden.ResultsA total of 301 children were enrolled (mean [SD] age, 11.9 [4.5] years; 172 [57%] female); 155 had ARP and 146 had CP. The majority of children with CP (123 of 146 [84%]) reported prior recurrent episodes of acute pancreatitis. Sex distribution was similar between the groups (57% female in both). Hispanic children were less likely to have CP than ARP (17% vs 28%, respectively; odds ratio [OR] = 0.51; 95% CI, 0.29-0.92; P = .02). At least 1 gene mutation in pancreatitis-related genes was found in 48% of patients with ARP vs 73% of patients with CP (P

ObjectiveTo estimate selected direct medical care costs of children with chronic pancreatitis (CP) and acute recurrent pancreatitis (ARP).MethodsWe performed a cross-sectional study of data from International Study Group of Pediatric Pancreatitis: In Search for a Cure (INSPPIRE), a multinational registry of children with ARP or CP. We determined health care utilization and estimated costs of hospitalizations, surgical and endoscopic procedures, and medications in our study population. Health care utilization data were obtained from all subjects enrolled in the study, and costs were calculated using national United States costs.ResultsWe included 224 subjects (median age 12.7 years), 42% of whom had CP. Mean number of hospitalizations, including for surgery and endoscopic retrograde cholangiopancreatography, was 2.3 per person per year, costing an estimated average $38,755 per person per year. Including outpatient medications, estimated total mean cost was $40,589 per person per year. Subjects using surgical procedures or endoscopic retrograde cholangiopancreatography incurred mean annual costs of $42,951 per person and $12,035 per person, respectively. Estimated annual costs of pancreatic enzyme replacement therapy, diabetic medications, and pain medications were $4114, $1761, and $614 per person, respectively. In an exploratory analysis, patients with the following characteristics appear to accrue higher costs than those without them: more frequent ARP attacks per year, reported constant or episodic pain, family history of pancreatic cancer, and use of pain medication.ConclusionsARP and CP are uncommon childhood conditions. The severe burden of disease associated with these conditions and their chronicity results in high health care utilization and costs. Interventions that reduce the need for hospitalization could lower costs for these children and their families.

ObjectiveTo determine the clinical presentation, diagnostic variables, risk factors, and disease burden in children with chronic pancreatitis.Study designWe performed a cross-sectional study of data from the International Study Group of Pediatric Pancreatitis: In Search for a Cure, a registry of children with acute recurrent pancreatitis and chronic pancreatitis. Between-group differences were compared using Wilcoxon rank-sum test.ResultsAmong 170 subjects in the registry, 76 (45%) had chronic pancreatitis; 57% were female, 80% were white; median age at diagnosis was 9.9 years. Pancreatitis-predisposing genetic mutations were identified in 51 (67%) and obstructive risk factors in 25 (33%). Toxic/metabolic and autoimmune factors were uncommon. Imaging demonstrated ductal abnormalities and pancreatic atrophy more commonly than calcifications. Fifty-nine (77%) reported abdominal pain within the past year; pain was reported as constant and receiving narcotics in 28%. Children with chronic pancreatitis reported a median of 3 emergency department visits and 2 hospitalizations in the last year. Forty-seven subjects (70%) missed 1 day of school in the past month as the result of chronic pancreatitis; 26 (34%) missed 3 or more days. Children reporting constant pain were more likely to miss school (P = .002), visit the emergency department (P = .01), and experience hospitalizations (P = .03) compared with children with episodic pain. Thirty-three children (43%) underwent therapeutic endoscopic retrograde pancreatography; one or more pancreatic surgeries were performed in 30 (39%).ConclusionsChronic pancreatitis occurs at a young age with distinct clinical features. Genetic and obstructive risk factors are common, and disease burden is substantial.

ObjectivesAcute recurrent pancreatitis (ARP) and chronic pancreatitis (CP) are rare and poorly understood diseases in children. Better understanding of these disorders can only be accomplished via a multicenter, structured, data collection approach.MethodsThe International Study Group of Pediatric Pancreatitis: In Search for a Cure (INSPPIRE) consortium was created to investigate the epidemiology, etiologies, pathogenesis, natural history, and outcomes of pediatric ARP and CP. Patient and physician questionnaires were developed to capture information on demographics, medical history, family and social history, medications, hospitalizations, risk factors, diagnostic evaluation, treatments, and outcome information. Information collected in paper questionnaires was then transferred into Research Electronic Data Capture (REDCap), tabulated, and analyzed.ResultsThe administrative structure of the INSPPIRE consortium was established, and National Institutes of Health funding was obtained. A total of 14 sites (10 in the United States, 2 in Canada, and 2 overseas) participated. Questionnaires were amended and updated as necessary, followed by changes made into the REDCap database. Between September 1, 2012 and August 31, 2013, a total of 194 children were enrolled into the study: 54% were girls, 82% were non-Hispanic, and 72% were whites.ConclusionsThe INSPPIRE consortium demonstrates the feasibility of building a multicenter patient registry to study the rare pediatric diseases, ARP and CP. Analyses of collected data will provide a greater understanding of pediatric pancreatitis and create opportunities for therapeutic interventional studies that would not otherwise be possible without a multicenter approach.

Young adults who have experienced recurrent acute pancreatitis and chronic pancreatitis as children or adolescents are vulnerable to poor follow-up and disease management during the transfer from the pediatric to adult healthcare system. Although formalized transition programs for young adults have been developed and described for other disease conditions, no such program has been described for young adults with pancreatic disease. This document is the first expert opinion outlining the important aspects of a transitional care and transfer program tailored to youth with recurrent acute and chronic pancreatitis. We emphasize the unique needs of these patients as they transfer to adult health care and the need for further research. The goal of improved transitional care and transfer is to enhance the services provided to adolescents/young adults with pancreatic disease in both healthcare settings and improve continuity of follow-up care. [ABSTRACT FROM AUTHOR]

During development, sympathetic neurons extend axons along a myriad of distinct trajectories, often consisting of arteries, to innervate one of a large variety of distinct final target tissues. Whether or [...]

Gariepy and colleagues (Gariepy CE, Williams SC, Richardson JA, Hammer RE, and Yanagisawa M. J Clin Invest 102: 1092-1101, 1998.) developed rescued spottinglethal rats that carry a naturally occurring deletion of the endothelin (ET) type B receptor gene resulting in a lack of functional renal ETB receptor expression. It has been shown that rats homozygous (sl/sl) for the deletion have elevated plasma ET-1 levels; thus, the purpose of this study was to determine whether this deletion would result in a downregulation of ETA receptors in renal tissue. ET-1 and ET-3 binding experiments were performed with cortex, outer medullary, and inner medullary membranes of heterozygous (sl/+) and si/si ETB receptor-deficient rats. [sup.125]I-labeled ET-1 binding in sl/sl cortex and outer medulla was significantly lower than cortex and outer medulla from sl/+ rats. In contrast to sl/+ rats, [sup.125]IET-3 binding was not detected in the cortex and outer medulla of sl/sl rats, indicating a lack of ETB receptor expression. The inner medulla of sl/+ rats also demonstrated an abundance of [ET.sub.B] receptors. Surprisingly, however, we also observed significant [125.sup.I]ET-3 binding in the sl/sl inner medulla. Furthermore, ET-3 binding in the inner medulla could be blocked with an E[T.sub.A] receptor antagonist in sl/sl rats but not in tissue from sl/+ rats. These studies indicate that rats deficient in ETB receptors have decreased renal cortical and outer medullary ETA receptor number, most likely in response to elevated plasma ET-1 levels. In addition, homozygous [ET.sub.B]-deficient rats express a novel inner medullary ET-3 binding site. endothelin B receptor; kidney; receptor binding; spottinglethal rats

Mechanisms by which endothelin (ET)-1 mediates chronic pulmonary hypertension remain incompletely understood. Although activation of the ET type A (E[T.sub.A]) receptor causes vasoconstriction, stimulation of ET type B (E[T.sub.B]) receptors can elicit vasodilation or vasoconstriction. We hypothesized that the E[T.sub.B] receptor attenuates the development of hypoxic pulmonary hypertension and studied a genetic rat mode] of E[T.sub.B] receptor deficiency (transgenic sl/sl). After 3 wk of severe hypoxia, the transgenic sl/sl pulmonary vasculature lacked expression of mRNA for the E[T.sub.B] receptor and developed exaggerated pulmonary hypertension that was characterized by elevated pulmonary arterial pressure, diminished cardiac output, and increased total pulmonary resistance. Plasma ET-1 was fivefold higher in transgenic sl/sl rats than in transgenic controls. Although mRNA for prepro-ET-1 was not different, mRNA for ET-converting enzyme-1 was higher in transgenic sl/sl than in transgenic control lungs. Hypertensive lungs of sl/sl rats also produced less nitric oxide metabolites and 6-ketoprostaglandin [F.sub.1[alpha]], a metabolite of prostacyclin, than transgenic controls. These findings suggest that the E[T.sub.B] receptor plays a protective role in the pulmonary hypertensive response to chronic hypoxia. endothelin receptors; hypoxia; pulmonary circulation; nitric oxide; prostacyclin