Pericardial fluid adenosine in ischemic and valvular heart disease

Adenosine released by ischemic myocardial cells stimulates coronary artery vasodilation. Measurement of adenosine concentrations in pericardial fluid in animal models of myocardial ischemia has been used to study the process of adenosine release. To determine whether pericardial fluid adenosine concentrations are increased in human ischemic heart disease, adenosine concentrations were measured in pericardial fluid in 23 subjects undergoing open-heart surgery for coronary artery disease. The results were compared with adenosine concentrations measured in pericardial fluid obtained from 20 subjects undergoing surgery for valvular heart disease. Adenosine concentrations also were measured in pleural fluid obtained during internal mammary artery bypass grafting. Adenosine concentrations were significantly increased in subjects with coronary artery disease compared with fluid obtained from subjects with valvular heart disease (2.47 +/- 0.24 vs 1.36 +/- 0.21 [SEM] microM [p = 0.0013]). Adenosine concentrations were higher in pleural fluid than pericardial fluid from the same individuals. Adenosine concentrations were significantly correlated with pericardial fluid cell counts and lactate dehydrogenase concentrations (r = 0.48; p = 0.0012 and r = 0.77, p = 0.0001, respectively). The results are consistent with myocardial release of adenosine in ischemic heart disease. If adenosine concentrations in pericardial fluid approximate those in myocardial interstitial fluid, sufficient adenosine is present to stimulate adenosine receptor activation in coronary artery smooth muscle.