The aim of this work was to investigate the effect of tissue culture on the intracellular amino acid pool in both freshly isolated and surgically prepared saphenous vein segments taken from patients undergoing coronary artery bypass surgery (number of patients, n = 8). Viability of freshly isolated vein rings, indicated by ATP concentration, was maintained in culture (321 +/- 41 vs. 277 +/- 31 nmol (g wet wt)-1, 0 vs. 14 days). The initial decrease in ATP concentration in surgically prepared rings was significantly reversed following 14 days in culture from 135 +/- 26 to 201 +/- 18 nmol (g wet wt)-1 (P < 0.05). Freshly isolated vein rings maintained their intracellular free amino acid pool during the 14 days in culture (from 166 +/- 25 to 166 +/- 23 mumol (g protein)-1). Surgical preparation of vein rings induced a decrease in the intracellular free amino acid pool (from 166 +/- 25 to 87 +/- 15 mumol (g protein)-1, P < 0.05). This decrease was partially reversed after 14 days in culture (140 +/- 19 mumol (g protein)-1). Although the total amino acid pool in both types of vein rings after 14 days in culture was similar, there were variations in individual amino acid concentrations. Freshly isolated rings showed an increase in glutamine concentration and a decrease in alanine and aspartate concentrations after 14 days in culture. Surgically prepared vein rings showed a decrease in aspartate concentration and an increase in concentrations of glutamine, asparagine, glutamate and glycine. The changes in individual intracellular free amino acid concentrations, which were largely determined by the corresponding concentrations in the medium, indicates that culture media should be supplemented with taurine, aspartate and alanine.