Regional difference of endogenous ATP release in the pulmonary artery of rabbits

1. The release of adenyl purines such as ATP, ADP, AMP and adenosine, from the pulmonary artery trunk (PAT), extrapulmonary artery (EPA) and intrapulmonary artery (IPA) were compared. 2. The amount of basal overflow of adenyl purines from the PAT was significantly smaller than those from EPA and IPA. There was no significant difference between the amount of the overflow from EPA and PAT. 3. Methoxamine, an alpha 1-adrenoceptor agonist, significantly increased the overflow of adenine nucleotides from the PAT, EPA and IPA, but did not increase those of adenosine. Methoxamine-induced release of adenyl purines from IPA was significantly larger than those from EPA and PAT. 4. These results suggest that an alpha 1-adrenoceptor-mediated mechanism for ATP-release is not homogeneously distributed in the pulmonary artery and a larger amount of ATP may be released in the peripheral part of the artery.