Release and regulation of endogenous adenosine during hemorrhage.

Pretreatment of animals with dilazep, a blocker of adenosine uptake, potentiated the increased concentrations of adenosine in venous blood by 6-fold and raised arterial adenosine concentrations by 3-fold. Pretreatment of animals with erythro-9-)2-hydroxy-3-nonyl)adenine (EHNA), an inhibitor of adenosine deaminase, also potentiated the increased concentrations of adenosine in venous blood by 6-fold and raised arterial adenosine concentrations by 3-fold. Pretreatment with combination of dilazep and EHNA furthermore increased venous adenosine levels by 11 times and arterial adenosine levels by 6 times. These data clearly suggest that hemorrhage induced extensive adenosine release and the released endogenous adenosine was eliminated quickly from plasma by the uptake mechanism and adenosine deaminase.