Vagal component in the chronotropic and dromotropic actions of adenosine and ATP

Several studies indicate that the vagus plays an important modulating role in the electrophysiologic actions of exogenous adenosine and ATP in the heart of certain mammalian species. In addition, extracellular adenosine can enhance the depressant effects of the vagus on the heart. These findings have immediate clinical implication with regard to the use of adenosine and ATP as antiarrhythmic agents as well as the mechanism of cardiac arrhythmias associated with high vagal tone and/or elevate extracellular adenosine levels.