Characterization of the facilitatory prejunctional purinoceptor on adrenergic nerves of the rabbit ear artery.
The effects of a number of purinoceptor agonists and antagonists on the release of endogenous norepinephrine (NE) from electrically field-stimulated (2 ms, 4 Hz) rabbit ear arteries were determined. NE was quantified by high-performance liquid chromatography and electrochemical detection techniques. Both P1- and P2-purinoceptor agonists enhanced the release of NE in a concentration-dependent manner (0.1 microM-100 microM), the relative order of potency being beta, gamma-methylene ATP (beta gamma-mATP) > 2-chloroadenosine (2CA) > ATP > L-phenylisopropyl-adenosine > 2-methylthio ATP > 5'N-ethylcarboxamido-adenosine. Adenosine and alpha, beta-methylene ATP (alpha beta-mATP) at 100 microM did not significantly enhance the electrical field stimulation-evoked release of NE. None of drugs changed the spontaneous overflow of NE. Pretreatment with alpha beta-mATP (1, 10 microM), a P2x-purinoceptor desensitizing agent, and 8-sulfophenyl theophylline (8SPT; 1 and 10 microM), a P1-purinoceptor antagonist, caused a shift to right of the concentration-release curve for beta gamma-mATP. alpha beta-mATP and 8SPT did not by themselves significantly affect the spontaneous overflow and the electrical field stimulation-evoked release of NE. Pretreatment of alpha beta-mATP (30 microM) and 8SPT (30 microM) antagonized facilitation of NE release by 2CA (10 microM). The concentration-contraction curve for beta gamma-mATP (1-300 microM) in the rabbit ear artery was shifted to the right by alpha beta-mATP (30 microM) but not by 8SPT (30 microM).(ABSTRACT TRUNCATED AT 250 WORDS)
Ishii
R
R
Department of Pharmacology, Meiji College of Pharmacy, Tokyo, Japan.
Shinozuka
K
K
Kunitomo
M
M
Hashimoto
T
T
Takeuchi
K
K
D015762:2-Chloroadenosine / Q000494:pharmacology; D000241:Adenosine / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000320:Adrenergic Fibers / Q000378:metabolism*; D000818:Animals; D001158:Arteries / Q000294:innervation; D004423:Ear / Q000098:blood supply; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D009638:Norepinephrine / Q000378:metabolism; D058913:Purinergic Agonists; D058914:Purinergic Antagonists; D011817:Rabbits; D011983:Receptors, Purinergic / Q000378:metabolism*; D013806:Theophylline / Q000031:analogs & derivatives / Q000494:pharmacology
D058913:Purinergic Agonists; D058914:Purinergic Antagonists; D011983:Receptors, Purinergic; D015762:2-Chloroadenosine; C005147:5'-adenylyl (beta,gamma-methylene)diphosphonate; C031433:8-(4-sulfophenyl)theophylline; D000255:Adenosine Triphosphate; D013806:Theophylline; D000241:Adenosine; C002630:alpha,beta-methyleneadenosine 5'-triphosphate; D009638:Norepinephrine