Arterial and venous plasma concentrations of adenosine during haemorrhage.

A haemorrhage model was used to impose severe metabolic stress in anaesthetized cats by removing blood (15.3 ml min-1) to attain an arterial pressure of ca. 50 mmHg for a 2 h period. Adenosine levels in central venous blood rose by 5 min, reached a peak of about 3.5 times control levels by 15 min and then returned to the basal level (1 microM) by 60 min. However, the adenosine concentration in arterial blood remained unchanged for the entire 2 h period of hypotension. These data demonstrate that haemorrhage results in rapid adenosine release, but the released adenosine is not able to serve a role as a systemic circulating vasodilator even in this severe model.