Inhibition of cardiac sympathetic neurotransmission by adenosine

Experiments were performed to study the effect of adenosine on sympathetic neurotransmission to the myocardium. Adenosine administration to pentobarbital-anesthetized dogs resulted in decrease in blood pressure and significant impairment of cardioacceleration produced by stimulation of cardiac sympathetic nerves. The positive chronotropic effect of intravenous norepinephrine was not affected by adenosine. The blood pressure lowering as well as the inhibitory effect of adenosine on cardiac sympathetic nerve function could be significantly antagonized by theophylline. These results provide in vivo evidence in support of the hypothesis that adenosine caused inhibition of sympathetic neurotransmission via an action on purinergic receptors located on sympathetic nerve terminals.