Purine release from vascular adrenergic nerves by high potassium and a calcium ionophore, A-23187.
The effect of high KCl and a Ca++-ionophore, A-23187, on 3H-purine efflux from [3H]adenosine-labeled pulmonary artery and thoracic aortic media of the rabbit was assessed. High KCl (30, 50 and 70 mM) and A-23187 (5 microM) markedly enhanced the efflux from the adrenergically innervated pulmonary artery. The KCl-induced increase of 3H-efflux was greatly diminished by removal of Ca++ from the medium and pretreatment with 6-hydroxydopamine (30 micrograms/ml) and cold storage (4 days), but not by treatment with reserpine and phentolamine. In contrast, the 3H-efflux induced by l-epinephrine was not affected by cold storage or 6-hydroxydopamine but was inhibited by phentolamine. 3H-purine efflux by A-23187 was also significantly reduced by Ca++ removal or cold storage. In the nerve-free aortic medial preparation, the efflux inducing effects of both KCl and A-23187 were very limited. The remaining effect of KCl in this tissue was not Ca++-dependent. From these results the efflux of 3H-purines induced by the high KCl or Ca++-ionophore appears to originate mainly from the amine-containing vesicles in adrenergic nerve terminals, probably through the Ca++-dependent exocytosis. This supports the view that the release of ATP and norepinephrine are coupled in adrenergic neurotransmission.
D000320:Adrenergic Fibers / Q000378:metabolism*; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001013:Aorta, Thoracic / Q000294:innervation; D000001:Calcimycin / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D003080:Cold Temperature; D003714:Denervation; D006892:Hydroxydopamines / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D011188:Potassium / Q000494:pharmacology*; D011651:Pulmonary Artery / Q000294:innervation; D011687:Purines / Q000378:metabolism*; D011817:Rabbits
D000900:Anti-Bacterial Agents; D006892:Hydroxydopamines; D011687:Purines; D000001:Calcimycin; D011188:Potassium; D002118:Calcium