Turnover of adenosine in plasma of human and dog blood.

摘要: To determine half-life and turnover of plasma adenosine, heparinized blood from healthy volunteers was incubated with radiolabeled adenosine in the physiological concentration range 0.1-1 microM. Plasma levels vitro were 82 +/- 14 nM similar to those determined immediately after collection a "stopping solution." Dipyridamole (83 microM) erythro-9(2-hydroxynon-3yl)-adenine (EHNA) (8 did not measurably alter basal but completely blocked uptake added adenosine. Inhibition ecto-5'-nucleotidase 100 microM alpha, beta-methyleneadenosine 5'-diphosphate (AOPCP) reduced 22 6 nM. For determination turnover, decrease specific radioactivity [3H]adenosine measured using dipyridamole-containing stopping solution. Without altering levels, estimated be 0.6 s. Similar experiments carried out washed erythrocytes or presence AOPCP, yielding half-lives 0.7 0.9 s, respectively. When initial 1 microM, its activity decreased by only 11% within 5 whereas total exponentially 1.5 Venous concentrations relief 3-min forearm ischemia. Changes correlate well changes flow augmented dipyridamole.(ABSTRACT TRUNCATED AT 250 WORDS)