Adenosine plasma concentration in pulmonary hypertension

Objective: In this study, we sought to appreciate the role of adenosine in the regulation of pulmonary vascular tone, especially in the case of clinic al pulmonary hypertension, by investigating the relationship between endoge nous plasma adenosine levels and pulmonary artery vasoconstriction. Methods : Adenosine plasma concentrations, were measured simultaneously in the dist al right pulmonary artery and in the femoral artery, both at steady state ( room air) and during pure oxygen inhalation, Three clinical situations were considered: (1) normal hemodynamics [7 control subjects, mean pulmonary ar tery pressure (MPAP) = 18.5 +/- 1 mmHg], (2) moderate pulmonary hypertensio n secondary to chronic obstructive pulmonary disease (COPD). (8 patients, M PAP = 31 +/- 3 mm Hg), (3) severe primary pulmonary hypertension (PPH), (8 patients, MPAP = 70 +/- 5 mm Hg). Results: In every instance, adenosine eva luated by HPLC was higher in the pulmonary than in the systemic circulation . For room air, adenosine plasma concentrations were significantly lower in COPD (0.49 +/- 0.16 mu mol l(-1)) and PPH patients (0.45 +/- 0.14 mu mol l (-1)) than in controls (1.26 +/- 0.12 mu mol l(-1)). During O-2 administrat ion, adenosine plasma concentrations all decreased but more so in COPD and PPH patients. The significant correlations between adenosine plasma concent rations and both pulmonary vascular resistance and PvO2, in controls, were not found in COPD or PPH patients. Conclusion: The adenosine plasma concent rations in the pulmonary circulation of PPH and COPD patients are low, and may contribute to pulmonary artery hypertension. (C) 1999 Elsevier Science B.V. All rights reserved.