Effect of adenyl purines on the release of endogenous noradrenaline from adrenergic nerves of rabbit ear artery

• Published in: Japanese Journal of Pharmacology 1993, Vol.61 (suppl.2), p.338-338
• Main Authors: Ishii, Reiko, Shinozuka, Kazumasa, Hattori, Keisuke, Akimoto, Hiroko, Takeuchi, Koichi, Hashimoto, Takao
• Format: Article
• Language: eng ; jpn
• ISSN: 0021-5198
• DOI: 10.1016/S0618-8278(19)31763-3

We have shown that methoxamine (MET) enhanced noradrenaline (NA) release via endogenous adenyl purines in rabbit ear artery (Jpn.J.Pharmacol., 58,172P,1992). In the present study, we examined the nature of prejunctional purinoceptors indirectly activated by MET in rabbit ear artery. NA and adenyl purines were quantified by HPLC-electrochemical and fluorescence detection, respectively. 1) MET (10^-5 M) enhanced NA-release to electrical stimulation (ES： 4 Hz, 2 msec), an action which was blocked by prazosin. MET at 10^-6 M did not affect the NA-release. 2) MET (10^-5 M) caused the release of adenyl urines, ATP, ADP, AMP and adenosine, an action which was blocked by prazosin. MET at 10^-6 M did not elicit the purines release. 3) Exogeneous ATP (10^-5 M) enhanced NA-release to ES. 4) The enhancements of NA-release by MET and ATP were blocked by P_2 -blocker suramin and α,β-methylene ATP and P_1 -antagonist 8-sulfophenyl theophylline. These results suggested that the prejunctional purinoceptor on adrenergic nerves of rabbit ear artery may not be adequately defined as either P_1 - or P_2 -purinoceptors.