Activation of ecto-5′-nucleotidase in the blood and hearts of patients with chronic heart failure

Background: Because plasma levels of adenosine are increased in patients with chronic heart failure (CHF), we examined adenosine concentrations in the plasma and heart and assessed the activity of ecto-5'-nucleotidase in the plasma and ventricular myocardium in patients with CHF. Methods and Results: We studied 36 patients with CHF (New York Heart Association Class I/II/II/IV, 9/8/12/7). Twenty-five subjects without CHF were used as controls. Both plasma adenosine levels and ecto-5'-nucleotidase activity were significantly higher in patients with CHF (219 +/- 28 nmol/L and 0.72 +/- 0.03 nmoL/mg protein/min, respectively) than in control subjects (71 +/- 8 nmol/L and 0.54 +/- 0.02 nmoL/mg protein/min, respectively). Plasma adenosine levels sampled from the coronary sinus were significantly higher than from the aorta in patients with CHF, but these differences were not observed in control subjects. Ecto-5'-nucleotidase protein levels were markedly increased in the ventricular myocardium in patients with CHF. Conclusions: These increases in ecto-5'-nucleotidase in the plasma and myocardium may contribute to increased plasma and cardiac adenosine levels. The increased ecto-5'-nucleotidase activity and adenosine levels in blood may become an index of the presence or severity of CHF.