title: Cardiovascular side-effects and insulin secretion after intravenous administration of radiolabeled Exendin-4 in pigs.
abstract: Radiolabeled Exendin-4, a synthetic glucagon-like peptide-1 (GLP-1) analog, is used as a tracer for diagnostic purposes of β-cells and in experimental animal research. Exendin-4 can be radiolabeled with (68)Ga, (111)In or (99m)Tc and used for positron emission tomography (PET) and single-photon emission computed tomography (SPECT) imaging to diagnose insulinomas, visualization of pancreatic β-cell mass and transplanted Islets of Langerhans. In humans, Exendin-4 is widely used as a therapeutic agent for treatment of type 2 diabetes (T2D). The compound, which is administered subcutaneously (SC) may cause nausea, vomiting and a minor increase in the heart rate (HR). However, possible side-effects on cardiovascular functions after intravenous (IV) administration have not been reported. This study describes the Exendin-4 dose at which cardiovascular side-effects occur in pigs and cynomolgus monkeys. The IV effect of the tracer on insulin secretion is also investigated in pigs.
  
  
  
  Seven clinically healthy littermate pigs (40days old) were used; three of them were made diabetic by streptozotocin (STZ). All pigs underwent PET imaging under general anesthesia to examine the glucagon-like peptide-1 receptor (GLP-1R) in β-cells with radiolabeled Exendin-4. A baseline tracer dose IV [(68)Ga]Exendin-4 (0.025±0.010μg/kg) followed by a competition dose IV [(68)Ga]Exendin-4 (3.98±1.33μg/kg) 60min later were administered. Blood samples were taken and analyzed for insulin secretion by using ELISA. Cardiovascular and respiratory variables were monitored throughout the experiment.
  
  
  
  Immediately after administration of the high dose [(68)Ga]Exendin-4 the HR rose from 122±14 to 227±40bpm (p<0.01) and from 100±5 to 181±13bpm (p<0.01) in healthy non-diabetic and diabetes-induced pigs, respectively. The tachycardia was observed for >2h and one healthy non-diabetic pig suffered cardiac arrest 3h after the IV [(68)Ga]Exendin-4. Arrhythmia was detected by listening to the heart with a stethoscope up to 4days after the [(68)Ga]Exendin-4 injection. In all animals, no effect on the cardiovascular system was registered after the low dose of IV [(68)Ga]Exendin-4. Insulin secretion increased (p<0.05) when IV [(68)Ga]Exendin-4 was given in dosages ≥0.14μg/kg.
  
  
  
  Intravenous administration of ≥2.8μg/kg [(68)Ga]Exendin-4 resulted in severe tachycardia and arrhythmias in healthy non-diabetic and diabetes-induced pigs, and the insulin secretion was stimulated in healthy non-diabetic animals when ≥0.14μg/kg [(68)Ga]Exendin-4 was given.
authors.affiliation: Department of Clinical Sciences, Faculty of Veterinary Medicine and Animal Science, Swedish University of Agricultural Sciences, Uppsala, Sweden. Electronic address: anneli.ryden@slu.se.
authors.forename: Anneli
authors.initials: A
authors.lastname: Rydén
authors.affiliation: Department of Clinical Sciences, Faculty of Veterinary Medicine and Animal Science, Swedish University of Agricultural Sciences, Uppsala, Sweden.
authors.forename: Görel
authors.initials: G
authors.lastname: Nyman
authors.affiliation: Department of Clinical Sciences, Faculty of Veterinary Medicine and Animal Science, Swedish University of Agricultural Sciences, Uppsala, Sweden.
authors.forename: Lovisa
authors.initials: L
authors.lastname: Nalin
authors.affiliation: Department of Clinical Sciences, Faculty of Veterinary Medicine and Animal Science, Swedish University of Agricultural Sciences, Uppsala, Sweden.
authors.forename: Susanne
authors.initials: S
authors.lastname: Andreasson
authors.forename: Irina
authors.lastname: Velikyan
authors.affiliation: Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden.
authors.forename: Olle
authors.initials: O
authors.lastname: Korsgren
authors.affiliation: Department of Medicinal Chemistry, Preclinical PET Platform, Uppsala University, Uppsala, Sweden.
authors.forename: Olof
authors.initials: O
authors.lastname: Eriksson
authors.affiliation: Department of Clinical Sciences, Faculty of Veterinary Medicine and Animal Science, Swedish University of Agricultural Sciences, Uppsala, Sweden.
authors.forename: Marianne
authors.initials: M
authors.lastname: Jensen-Waern
mesh_terms: D061605:Administration, Intravenous; D000818:Animals; D062186:Arterial Pressure / Q000187:drug effects; D001786:Blood Glucose / Q000378:metabolism; D002319:Cardiovascular System / Q000000981:diagnostic imaging / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D000077270:Exenatide; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D007328:Insulin / Q000097:blood / Q000378:metabolism*; D000078790:Insulin Secretion; D008297:Male; D010455:Peptides / Q000008:administration & dosage* / Q000009:adverse effects*; D049268:Positron-Emission Tomography; D013552:Swine; D014688:Venoms / Q000008:administration & dosage* / Q000009:adverse effects*
chemical_list: D001786:Blood Glucose; D007328:Insulin; D010455:Peptides; D014688:Venoms; D000077270:Exenatide
keywords: Adverse-effects; Arrhythmias; Exenatide; Imaging; Monkeys; PET; Swine; Tachycardia