Hussain K, Bryan J, Christesen HT, Brusgaard K, Aguilar-Bryan L. Serum glucagon counterregulatory hormonal response to hypoglycemia is blunted in congenital hyperinsulinism. glucose tolerance or insulin sensitivity (13). These findings suggest that GLP-1 and its receptor play a key role in the control of insulin secretion in this mouse model. We hypothesized that exendin-(9-39) can elevate fasting blood glucose levels in children and adults with KATPHI and, thus, may have a potential therapeutic application for this disorder. To evaluate this hypothesis, we examined the effect of exendin-(9-39) on glucose homeostasis in subjects with congenital hyperinsulinism. Given the dearth of available effective medical therapies for individuals with KATPHI, these studies are important in understanding the pathophysiology of this disorder and evaluating the potential therapeutic applications of antagonists of the GLP-1 receptor in the treatment of this serious condition. RESEARCH DESIGN AND METHODS Nine subjects with confirmed genetic and clinical diagnosis of KATP hyperinsulinism were recruited from the Hyperinsulinism Center at the Childrens Hospital of Philadelphia (CHOP). Exclusion criteria included acute medical illnesses; a history of systemic chronic diseases such as cardiac failure, renal insufficiency, hepatic insufficiency, chronic obstructive pulmonary disease, anemia, or uncontrolled hypertension; pregnancy; diabetes; and use of medications that affect glucose metabolism, such as glucocorticoids, -agonists, octreotide, Araloside V and diazoxide. This was a randomized, open-label, two-period complete crossover pilot study to evaluate the effect of the GLP-1 receptor antagonist exendin-(9-39), on glucose metabolism in subjects with KATPHI. The study was approved by the human subjects committee of CHOP and the U.S. Food and Drug Administration. Written informed consent was obtained from all subjects or their parent/guardian. Assent was obtained from the children when appropriate. Subjects were admitted to the CHOP Clinical and Translational Research Center (CTRC) inpatient unit. All subjects were administered 5 ng exendin-(9-39) (0.05 g/mL) intradermally as a test of immediate hypersensitivity. Baseline chemistry profiles were obtained to evaluate liver and kidney function in all subjects, and a pregnancy test was performed in all postmenarchal females. An antecubital vein was cannulated in each forearm for infusions and blood sampling. Each subject underwent two experiments in random order and on consecutive days. On one day, Araloside V after a 12-h overnight fast, subjects received an intravenous infusion of vehicle (0.9% Rabbit Polyclonal to GPR132 NaCl) for 1 h followed by an intravenous infusion of exendin-(9-39) at 100 pmol/kg/min (0.02 mg/kg/h) for 2 h and then 300 pmol/kg/min (0.06 mg/kg/h) for 2 h, followed by 500 pmol/kg/min (0.1 mg/kg/h) for the last 2 h. The doses of exendin-(9-39) Araloside V were selected based on previously published data demonstrating that at a dose of 300 pmol/kg/min, exendin-(9-39) abolishes the effects of physiologic postprandial plasma concentrations Araloside V of GLP-1 and that a higher dose of 500 pmol/kg/min increases fasting plasma glucose concentration in normal subjects (5,12). On the other day, after a 12-h overnight fast, subjects received an intravenous infusion of vehicle for 7 h. The infusion rates of vehicle were identical to the volume infused during the exendin-(9-39) study day. The primary outcome for this study was fasting blood glucose concentration. Secondary outcomes include fasting plasma insulin, C-peptide, glucagon, intact GLP-1, and insulin/glucose. Blood samples for blood glucose, insulin, glucagon, and intact GLP-1 were obtained at multiple time points during the infusions (?60, 0, 40, 60, 80, 120, 160, 180, 200, 220, 240, 280, 300, 320, 340, and 360 min). During the infusion, blood glucose was monitored by a bedside glucose meter (Surestep) as needed to avoid hypoglycemia (defined as 3.9 mmol/L [70 mg/dL]). An intravenous infusion of dextrose was started if blood glucose levels fell to 3.3 mmol/L (60 mg/dL) during the study period. Peptide. Exendin-(9-39) was synthesized by the American Peptide Company (Sunnyvale, CA) under cGMP guidelines. The peptide was purified to 97% by high-performance liquid chromatography, and the sequence and mass were verified. The peptide was stored in a lyophilized form at ?20C. For administration, the peptide was diluted in 0.9% NaCl and added to 0.25% human serum albumin (final concentration of 0.1 mg/mL). Aliquots were tested for sterility and pyrogenicity through the Investigational Drug Support at the University of Pennsylvania. The use of synthetic exendin-(9-39) is approved under the U.S. Drug and Meals Administration Investigational New Medication zero. 76612. Islet research. Refreshing pancreata from medical specimens from three neonates (age group 4C6 weeks) with KATPHI who have been homozygous for mutations in either (R136L) or (R248X and E824X) had been procured via an institutional.