CARDIOVASCULAR AND RESPIRATORY EFFECTS OF ADENOSINE IN HUMANS AFTER PULMONARY DENERVATION

Adenosine infusion causes tachycardia in normal subjects. A proposed m echanism is secondary pulmonary stretch receptor activation due to hyp erventilation, induced by direct stimulation of carotid body chemorece ptors by adenosine. We examined responses to adenosine (incremental do ses given by intravenous infusion, 5 min each rate) in six normal volu nteers and six lung-transplant recipients with pulmonary denervation. Adenosine caused chemoreceptor stimulation in both groups with minute ventilation increasing from 5.8 +/- 0.4 to; 10.7 +/- 1.3 l/min (P < 0. 05) in the volunteers and from 4.8 +/- 0.4 to 9.2 +/- 0.8 l/min (P < 0 .001) in the lung-transplant recipients. There was no difference in th e magnitude of the ventilatory increase between the two groups (P = NS at all infusion rates). Adenosine produced tachycardia in both groups , with heart rate increasing from 66 +/- 5 to 84 +/- 3 beats/min (P < 0.01) in the volunteers and from 82 +/- 6 to 110 +/- 6 beats/min (P < 0.05) in the lung-transplant recipients. There was no difference in th e magnitude of the heart rate response between the two groups (P = NS at all infusion rates). These data suggest, contrary to previous think ing, that pulmonary stretch receptor activation does not contribute to adenosine-induced tachycardia in humans.