title: The effects of acute elevations in plasma cortisol levels on alanine metabolism in the conscious dog.
abstract: The present study was undertaken to determine whether an acute physiological increase in plasma cortisol level had significant effects on alanine metabolism and gluconeogenesis within 3 hours in conscious, overnight-fasted dogs. Each experiment consisted of an 80-minute tracer and dye equilibration period, a 40-minute basal period, and a 3-hour experimental period. A primed, continuous infusion of [3-3H]glucose and continuous infusions of [U-14C]alanine and indocyanine green dye were initiated at the start of the equilibration period and continued throughout the experiment. Dogs were studied with (1) a hydrocortisone infusion ([CORT] 3.0 micrograms.kg-1.min-1, n = 5), (2) hydrocortisone infused as in CORT, but with pancreatic hormones clamped using somatostatin and basal intraportal replacement of insulin and glucagon (CLAMP+CORT, n = 5), or (3) saline infusion during a pancreatic clamp (CLAMP, n = 5). Glucose production and gluconeogenesis were determined using tracer and arteriovenous difference techniques. During CLAMP, all parameters were stable except for a modest 67% +/- 6% increase in gluconeogenic conversion of alanine to glucose and a 53% +/- 26% increase in gluconeogenic efficiency. When plasma cortisol levels were increased fourfold during CLAMP+CORT, there was no change in the concentration, production, or clearance of glucose. Gluconeogenic conversion of alanine to glucose increased 10% +/- 34% and gluconeogenic efficiency increased 65% +/- 43%, while net hepatic alanine uptake (NHAU) increased 60% +/- 19% and hepatic fractional extraction of alanine increased 38% +/- 12%. Cortisol did not cause an increase in the arterial glycerol level or net hepatic glycerol uptake.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Molecular Physiology and Biophysics, Surgery, Vanderbilt University School of Medicine, Nashville, TN 37232.
authors.forename: R E
authors.initials: RE
authors.lastname: Goldstein
authors.forename: G W
authors.initials: GW
authors.lastname: Reed
authors.forename: D H
authors.initials: DH
authors.lastname: Wasserman
authors.forename: P E
authors.initials: PE
authors.lastname: Williams
authors.forename: D B
authors.initials: DB
authors.lastname: Lacy
authors.forename: R
authors.initials: R
authors.lastname: Buckspan
authors.forename: N N
authors.initials: NN
authors.lastname: Abumrad
authors.forename: A D
authors.initials: AD
authors.lastname: Cherrington
mesh_terms: D020155:3-Hydroxybutyric Acid; D000409:Alanine / Q000378:metabolism*; D000818:Animals; D001786:Blood Glucose / Q000032:analysis / Q000378:metabolism; D050260:Carbohydrate Metabolism; D002250:Carbon Radioisotopes; D003243:Consciousness / Q000502:physiology*; D004285:Dogs; D004837:Epinephrine / Q000097:blood; D005260:Female; D005934:Glucagon / Q000097:blood; D005943:Gluconeogenesis / Q000187:drug effects; D005947:Glucose / Q000378:metabolism / Q000502:physiology; D005990:Glycerol / Q000097:blood / Q000378:metabolism; D006854:Hydrocortisone / Q000008:administration & dosage / Q000097:blood* / Q000502:physiology*; D006885:Hydroxybutyrates / Q000097:blood / Q000378:metabolism; D007328:Insulin / Q000097:blood; D007773:Lactates / Q000097:blood; D008099:Liver / Q000378:metabolism; D008297:Male; D009638:Norepinephrine / Q000097:blood; D013997:Time Factors
chemical_list: D001786:Blood Glucose; D002250:Carbon Radioisotopes; D006885:Hydroxybutyrates; D007328:Insulin; D007773:Lactates; D005934:Glucagon; D005947:Glucose; D000409:Alanine; D005990:Glycerol; D020155:3-Hydroxybutyric Acid; D006854:Hydrocortisone; D009638:Norepinephrine; D004837:Epinephrine