title: Plasma glucagon-immunoreactive components in early life in dogs.
abstract: High plasma concentrations of C-terminal immunoreactive glucagon (IRG) have been found during early life in several mammalian species. We have analyzed the plasma IRG of 12 h to 60 day-old dogs in terms of the 4 peaks (IRG greater than 20,000, IRG9000, IRG3500 and IRG2000) obtained by gel filtration on Bio-Gel P-30. Significant changes with age and in response to administered agents were confined to IRG9000 and IRG3500. IRG9000 was 9-fold higher in 12-36 h old dogs than in adults (108 +/- 24 pg/ml pancreatic glucagon equivalents v. 12 +/- 3 pg/ml, mean +/- SEM) and showed a decline to 2-fold higher (27 +/- 5 pg/ml) at 31-60 days. IRG3500 was higher than in the adult only during the first 36 h of life (36 +/- 5 pg/ml v. 15 +/- 3 pg/ml). Arginine infusion (0.5 g/kg over 15 min) caused an increase in plasma levels of both IRG9000 and IRG3500 in the newborn, whereas in adult dogs only IRG3500 was increased. Insulin injection (0.2 U/kg intravenously) causing a marked hypoglycemia had no significant effect on the plasma level of any IRG component in newborn dogs. Dihydrosomatostatin infusion (10 micrograms/kg bolus +/- 90 micrograms/kg over 30 min) caused a decrease in both IRG9000 and IRG3500. The increased basal level and secretory response to arginine of IRG9000 in newborn dogs may reflect an immaturity of the A cells, whereby more of this component, which may represent a precursor of pancreatic glucagon, is secreted than in the adult. The immature A cells also appear to have an impaired secretory response to hypoglycemia.
authors.forename: M
authors.initials: M
authors.lastname: Ghiglione
authors.forename: J M
authors.initials: JM
authors.lastname: Pascual
authors.forename: A
authors.initials: A
authors.lastname: Rovira
authors.forename: G
authors.initials: G
authors.lastname: Calvo
authors.forename: I
authors.initials: I
authors.lastname: Valverde
mesh_terms: D000375:Aging; D000818:Animals; D000831:Animals, Newborn; D001120:Arginine / Q000494:pharmacology; D004285:Dogs; D005934:Glucagon / Q000097:blood*; D004763:Glucagon-Like Peptides; D007328:Insulin / Q000494:pharmacology; D010455:Peptides / Q000097:blood*; D011863:Radioimmunoassay; D013004:Somatostatin / Q000494:pharmacology
chemical_list: D007328:Insulin; D010455:Peptides; D013004:Somatostatin; D004763:Glucagon-Like Peptides; C015236:glucagon-like-immunoreactivity; D005934:Glucagon; D001120:Arginine