0.57 METABOLISM OF AAINO ACIDS (AA) IN ISOLATED PERFUSED RAT LIVER (IPRL). J.P. Debandt, F.Ballet, L. Cynober, C. Rey, C. Coudray-Lucas, J. Giboudeau. Lab. Biochimie A et U. d'HBpatologie INSERM, HBp. St Antoine, Paris - France.

The influence of the AA composition of the perfusion medium on AA hepatic uptake was examined. Livers (n q 11) from Sprague-Dawley rats (weight : 220 g) were perfused for two hours in a recirculating system with whole rat blood diluted (1:3) in Krebs-albumin buffer with various AA concentrations : group A, no AA added ; wow 6, addition at t0 of 8 AA (known for their antiproteolytic properties) at twice physiological levels (2x) ; group C as group 8 + addition at t60 min of a balanced AA mixture (2x). Results for 3 representative AA (expressed as nmol/min.g liver) were as follows :

ALANINE LEUCINE PHENYLALANINE 1st hour 2nd hour 1st hour 2nd hour 1st hour 2nd hour

group A + 7+ 6 - 19 2 12 - 32 + lo* - 45 2 7* - 11 + 3" -3? 1* group 8 + 148 2 42* + 26 + 15* - 18 2 9* - 50 2 i3* + 6?4* +3+ 4 group C + 160 ? 69* + 39 + 17" - 16 ? 9* - 20 ? 11* + 6+5 +45 z 20* positive values : uptake ; negative values : release ; *p < 0.05 : significant release or uptake.

Thus, marked proteolysis occurred when an unsupplemented medium was used (group A). Proteolysis was inhibited only the first hour in group B. Only the double AA supplementation (to and t 60 min) blocked proteolysis-and allowed consistent uptake of gluconeogenic AA throughout the period of the experiment and this protocol is therefore suitable for the study of AA metabolism in IPRL.

0.55 EFFECT OF CHRONIC SUBMAXIMAL EXERCISE ON SKELETAL MUSCLE COMPOSITION DURING INTRAVENOUS FEEDING IN NORMAL MAN. A.Legaspi, JU Albert, JP Roberts, GT Shires, SF Lowry.The New York Hospital-Cornell lJniver??-ty Medical Center and University of Miami School of Medicine.

Acute changes in skeletal muscle (SK) amino acid concentrations ([AA]) have been observed durins hospitalization after injury. To determine the effect of uncomplicated hospitaliz- ation; simultaneous provision of adequate protein and calories, with and without anabolic stimulation was done in weight-stable adult volunteers. Total parenteral nutrition (TPN) was administered for 10 days to hospitalized males. Five subjects underwent one hour of daily cycle ergometry at 40% of their VOpmax (EXE), while four subjects received TPN and did not exercise (NOEX). SK membrane potential (Em) in mV, intracellular water (H2Oi) in g/kg wet SK, free intracellular non-essential ([NEAA]i), essential ([EAA]i) in mmol/l of H2Oi, plasma non-essential ([NEAA]e), and essential ([EAA]e) amino acids in mmol/l were determined on the tenth TPN day. Em was measured with Ling-Gerard electrodes and used to calculate HpOi with the Nernst equation, SK was obtained by needle biopsy, and AA were determined by column chromatography. Results in table are expressed as MEAN+SEM.

[NEAA]e [NEAA]i [EAA]e [EAA]i Em H2Oi EXE 2.9tO.l" 23.5t2.4 1.5kO.l 3.2kO.5 68+1 733t18* NOEX 2.6iO.l 18.8t3.8 1.3'10.1 2.2i0.3 72t2 657+33 p 0.05 by unpaired Student's t-test.

Increased [NEAA]e observed in the EXE 9roup, while [AA]i are comparable in both grouos, suqqests accelerated whole-body amino acid turnover in the EXE subjects. Expansion of the-H$i comnart!:;ent in the EXE-group indicates an increase in the intracellular amino alid pool in SK. These chanqes in [AA] bolic stimuation during TPN: Unchanoed

may represent SK and whole-body adaptation to ana- Em in SK in this unstressed model may indicate in-

tact electrical charge and electrolyte homeostasis at the cellular level in the -presence of a moderate anabolic stimulus.

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