Adenine nucleotide synthesis in human erythrocytes depends on the mode of supplementation of cell suspension with adenosine

In suspensions of washed human erythrocytes, adenosine added in a single do se to concentrations of 0.1-10.0 mmol/l suspension was deaminated at rates ranging from 10 to 50 mmol/l cells h. The sum of adenosine, inosine, and hy poxanthine concentrations in the suspension, as well as the intracellular c oncentration of ATP, remained constant. In the presence of 25-50 mmol/l ort hophosphate, addition of a single dose of adenosine into erythrocyte suspen sion increased the ATP concentration by up to 280% of the initial level. If the initial adenosine concentrations were greater than 5 mmol/l suspension , ATP increased independently of adenosine concentration to the level deter mined only by the concentration of orthophosphate. After orthophosphate was returned to its initial level, ATP in erythrocytes began to decrease. In t he presence of coformycin, erythrocytes utilized adenosine at a rate of 0.2 -0.3 mmol/l cells h. Their adenylate pool increased at a rate of 0.10-0.16 mmol/l cells h for several hours, but intracellular ATP increased only slig htly. The energy charge of cells decreased significantly from 0.86 +/- 0.05 (control) to 0.82 +/- 0.06. Adenosine continuously pumped into erythrocyte suspensions at rates of 0.02-5.0 mmol/l cells h for several hours caused t he adenylate pool of erythrocytes and intracellular ATP to increase synchro nously at a rate of 0.02-0.35 mmol/l cells h. The energy charge of these er ythrocytes increased significantly up to 0.91 +/- 0.03. After pumping of ad enosine was stopped, the intracellular ATP and the adenylate pool began to decrease, returning sometimes to the initial level in 2-3 h.