Changes in intracellular concentration of amino acids in human saphenous vein during preparation for coronary artery bypass grafting.
OBJECTIVE
Earlier research on human skeletal and cardiac muscle has shown a fall in the intracellular free amino acid pool, particularly the non-essential amino acids, during surgery. Surgical preparation of the human saphenous vein for coronary artery by pass grafting has been shown to provoke metabolic damage and may therefore induce changes in cellular amino acids which may have long-term implications for the performance of the grafted vein. This work investigates the hypothesis that surgical preparation of saphenous vein induces changes in amino acids.


METHODS
Changes in the intracellular free amino acid pool were monitored, using high-performance liquid chromatography (HPLC), in both freshly isolated and surgically prepared human saphenous veins during coronary artery bypass grafting. In order to asses the extent of metabolic damage incurred by surgical preparation, adenosine triphosphate (ATP) levels were also measured.


RESULTS
A substantial fall in intracellular free amino acid was associated with surgical preparation of human saphenous vein for coronary artery bypass grafting (190.8 +/- 25 to 106 +/- 18 mumol.g-1 protein, n = 10, P < 0.05). Although the fall was seen in most amino acids detected, it was marked and statistically significant (P < 0.05) for taurine (30.6 +/- 3.1 to 9.0 +/- 2.2 mumol.g-1 protein), glutamate (43.6 +/- 5.6 to 18.2 +/- 4.5 mumol.g-1 protein), glutamine (12.8 +/- 1.6 to 3.3 +/- 1.2 mumol.g-1 protein) and asparagine (9.6 +/- 1.6 to 4.1 +/- 1.0 mumol.g-1 protein). The fall in tissue taurine which would be largely due to transport showed a strong positive correlation with the fall seen in glutamate, glutamine and asparagine. ATP levels significantly decreased as a result of surgical preparation (279 +/- 44 to 96 +/- 21 nmol.g-1 wet weight, P < 0.05). The fall in ATP was accompanied by an increase in alanine/glutamate ratio which may reflect increased glutamate-alanine transaminase activity and therefore metabolic changes.


CONCLUSIONS
The metabolic damage associated with surgical preparation of human saphenous vein for coronary artery bypass grafting is accompanied by a fall in the intracellular free amino acid pool which is marked and statistically significant for glutamate, taurine, glutamine and asparagine. The fall is likely to be due to transport metabolism may also contribute. This may have important implications for the functional recovery of the grated vein.
Suleiman
M S
MS
University Department of Cardiac Surgery, Bristol Royal Infirmary, UK.
Wallace
D
D
Birkett
S
S
Angelini
G D
GD
D000255:Adenosine Triphosphate / Q000032:analysis; D000596:Amino Acids / Q000378:metabolism*; D001216:Asparagine / Q000378:metabolism; D001692:Biological Transport; D002851:Chromatography, High Pressure Liquid; D001026:Coronary Artery Bypass; D018698:Glutamic Acid / Q000378:metabolism; D005973:Glutamine / Q000378:metabolism; D006801:Humans; D007424:Intracellular Fluid / Q000378:metabolism*; D012501:Saphenous Vein / Q000201:enzymology / Q000378:metabolism* / Q000601:surgery; D013654:Taurine / Q000378:metabolism
D000596:Amino Acids; D005973:Glutamine; D013654:Taurine; D018698:Glutamic Acid; D001216:Asparagine; D000255:Adenosine Triphosphate