Effect of Adenosine on Adrenergic Neurotransmission in the Superfused Rat Portal Vein

Publisher Website
Google Scholar
Abstract
This study examined the effect of exogenously applied adenosine on the release of 3H-norepinephrine from the field-stimulated, superfused rat portal vein. Adenosine was found to inhibit the field-stimulated release of 3H-norepinephrine in a dose-dependent manner in 50- to 1,000-µM concentrations. The effect was reversed when adenosine was washed out. The inhibitory effects of adenosine were antagonized by theophylline (10–4M) which by itself showed a slight enhancement of stimulated 3H-norepinephrine release. ATP was found to inhibit 3H-norepinephrine release at the same concentration as adenosine while inosine was inactive. When adenosine was tested in the presence of the muscarinic and α-adrenergic blocking agents atropine and phenoxybenzamine along with indomethacin, a prostaglandin synthesis inhibitor, its inhibitory effect on the stimulated release of 3H-norepinephrine persisted. It is concluded that adenosine and/or ATP can modulate the nerve-stimulated induced release of norepinephrine presumably by an action on the adrenergic nerve terminals.