title: Effects of differing insulin levels on response to equivalent hypoglycemia in conscious dogs.
abstract: The aim of this study was to determine if differing concentrations of insulin can modify the counterregulatory response to equivalent hypoglycemia. Insulin was infused intraportally into normal 18-h-fasted conscious dogs at 2 (low, n = 6) or 8 mU.kg-1.min-1 (high, n = 7) on separate occasions. This resulted in steady-state arterial insulin levels of 80 +/- 8 and 610 +/- 55 microU/ml, respectively. Glucose was infused during the high dose to maintain plasma glucose similar to low (50 +/- 1 mg/dl). Despite similar plasma glucose levels, epinephrine (2,589 +/- 260, 806 +/- 180 pg/ml), norepinephrine (535 +/- 60, 303 +/- 55 pg/ml), cortisol (12.1 +/- 1.5, 5.8 +/- 1.2 micrograms/dl), and pancreatic polypeptide (1,198 +/- 150, 598 +/- 250 pg/ml) were all increased in the presence of high-dose insulin (P < 0.05). Glucagon levels were similar during both insulin infusions. Hepatic glucose production, measured with [3-3H]-glucose, rose from 2.6 +/- 0.2 to 4.7 +/- 0.3 mg.kg-1.min-1 in response to high insulin (P < 0.01) but remained unchanged, 3.0 +/- 0.5 mg.kg-1.min-1, during low-dose infusions. Six hyperinsulinemic euglycemic control experiments (2 or 8 mU.kg-1.min-1, n = 3 in each) provided baseline data. By the final hour of the high-dose euglycemic clamps, cortisol (2.4 +/- 0.4 to 4.8 +/- 0.8 micrograms/dl) and norepinephrine (125 +/- 34 to 278 +/- 60 pg/ml) had increased (P < 0.05) compared with baseline. Plasma epinephrine levels remained unchanged during both series of euglycemic studies.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Molecular Physiology and Biophysics, Vanderbilt University Medical School, Nashville, Tennessee 37232-0615.
authors.forename: S N
authors.initials: SN
authors.lastname: Davis
authors.forename: R
authors.initials: R
authors.lastname: Dobbins
authors.forename: C
authors.initials: C
authors.lastname: Tarumi
authors.forename: C
authors.initials: C
authors.lastname: Colburn
authors.forename: D
authors.initials: D
authors.lastname: Neal
authors.forename: A D
authors.initials: AD
authors.lastname: Cherrington
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D002319:Cardiovascular System / Q000503:physiopathology; D004285:Dogs; D005260:Female; D005947:Glucose / Q000378:metabolism; D015309:Glucose Clamp Technique; D006728:Hormones / Q000097:blood; D007003:Hypoglycemia / Q000097:blood* / Q000503:physiopathology; D007328:Insulin / Q000097:blood*; D007700:Kinetics; D008297:Male; D012016:Reference Values
chemical_list: D001786:Blood Glucose; D006728:Hormones; D007328:Insulin; D005947:Glucose