Effect of systemic hyperinsulinemia on amino acid flux across human legs in postabsorptive state.
The effect of physiological hyperinsulinemia (approximately 110 mU/l) on leg tissue protein balance was investigated in eight weight-stable healthy individuals. A primed constant infusion of L-[U-14C]tyrosine was used to measure the disposal and release of tyrosine across the leg before and during 2 h of euglycemic clamp studies. The leg exchange of 3-methyl-L-histidine (3-MH) and all amino acids in blood were measured before and during insulinization, including the muscle tissue content of amino acids. Hyperinsulinemia decreased whole body tyrosine flux from 52 +/- 2 to 35 +/- 1 mumol/min (P less than 0.0001), whereas neither disposal (53 +/- 9 vs. 45 +/- 9 nmol.min-1.100 g-1) nor release of tyrosine across the leg (76 +/- 11 vs. 66 +/- 10 nmol X min-1 X 100 g-1) was significantly influenced. The arterial concentration and the leg exchange of 3-MH were not significantly affected by 2 h of hyperinsulinemia, but the sum of all amino acids declined significantly. The net leg balance of tyrosine was not affected at all by hyperinsulinemia, whereas the balance of the branched-chain amino acids and methionine were switched from efflux toward influx. Phenylalanine efflux from the leg only showed a trend to a significant effect by insulin. The muscle tissue concentration of six individual amino acids decreased significantly during hyperinsulinemia, particularly the branched-chain amino acids. The leg exchange of glucose, free fatty acids, and glycerol immediately changed significantly, as expected in response to insulinization.(ABSTRACT TRUNCATED AT 250 WORDS)
Arfvidsson
B
B
Department of Surgery, University of Gothenburg, Sweden.
Zachrisson
H
H
Möller-Loswick
A C
AC
Hyltander
A
A
Sandström
R
R
Lundholm
K
K
D000596:Amino Acids / Q000097:blood / Q000378:metabolism*; D001786:Blood Glucose / Q000378:metabolism; D005230:Fatty Acids, Nonesterified / Q000097:blood; D006801:Humans; D006946:Hyperinsulinism / Q000378:metabolism*; D007328:Insulin / Q000097:blood / Q000494:pharmacology; D007700:Kinetics; D007866:Leg / Q000098:blood supply; D008297:Male; D008875:Middle Aged; D009132:Muscles / Q000187:drug effects / Q000378:metabolism*; D011188:Potassium / Q000097:blood; D011506:Proteins / Q000378:metabolism; D012039:Regional Blood Flow; D013997:Time Factors; D014443:Tyrosine / Q000378:metabolism*
D000596:Amino Acids; D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D011506:Proteins; D014443:Tyrosine; D011188:Potassium