Amino acids augment insulin's suppression of whole body proteolysis

Journal Article · Fri Dec 01 04:00:00 EST 1989 · American Journal of Physiology; (USA)

OSTI ID:7105763

Flakoll, P J; Kulaylat, M; Frexes-Steed, M; Hourani, H; Brown, L L; Hill, J O; Abumrad, N N ^[1]

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1. Vanderbilt Univ. Medical Center, Nashville, TN (USA)

Leucine (LEU) kinetics were assessed using a primed-continuous infusion of L-(1-14C)LEU in normal overnight-fasted male volunteers during a basal period and an experimental period where insulin (INS) was infused at either 0.6, 1.2, 2.5, 5.0, 10, or 20 mU.kg-1.min-1 with euglycemia maintained. Two protocols were used: subjects were allowed to develop hypoaminoacidemia or plasma essential amino acids (AA) were maintained near basal levels by frequently monitoring plasma LEU in conjunction with variable infusions of an AA solution (LEU infused = 0.41, 0.72, 0.93, 1.03, 1.31, and 1.35 mumol.kg-1.min-1 at escalating INS doses, respectively). Basal rates of LEU appearance (Ra), nonoxidative disappearance (NORd) and oxidative disappearance (OXRd) were similar in both protocols (means = 1.74, 1.40, and 0.36 mumol.kg-1.min-1, respectively). INS infusions without AA resulted in a progressive decrement in LEU Ra (14 to 45%), NORd (16-41%), and OXRd (3-56%) compared with basal values. The infusion of AA resulted in an additional reduction in endogenous Ra (P less than 0.01; approximately 100% suppression achieved at plasma INS greater than 1,000 microU/ml) and a blunting of NORd reduction (P less than 0.05) at each dose of INS. Observed differences in INS's suppression of LEU Ra between the two protocols suggests the existence of a component of whole body proteolysis that is highly dependent on circulating plasma AA. Therefore, hypoaminoacidemia associated with INS treatment would appear to blunt the responsiveness of INS's suppression of protein breakdown and in the presence of near basal plasma AA, proteolytic suppression by INS is enhanced.

• OSTI ID: 7105763
• Journal Information: American Journal of Physiology; (USA), Journal Name: American Journal of Physiology; (USA) Vol. 257; ISSN 0002-9513; ISSN AJPHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AMINO ACIDS
ANIMALS
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL FUNCTIONS
CARBON 14 COMPOUNDS
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
DECOMPOSITION
FASTING
FUNCTIONS
HORMONES
INHIBITION
INSULIN
ISOTOPE APPLICATIONS
ISOTOPE DILUTION
KINETICS
LABELLED COMPOUNDS
LEUCINE
MAMMALS
MAN
ORGANIC ACIDS
ORGANIC COMPOUNDS
PEPTIDE HORMONES
PRIMATES
PROTEOLYSIS
REACTION KINETICS
TRACER TECHNIQUES
VERTEBRATES