Autonomic neural control of cardiac function: modulation by adenosine and adenosine 5'-triphosphate

Adenosine and adenosine 5'-triphosphate (ATP) are found in every cell of the human body. These molecules are released from cells into the extracellular fluid under physiologic and pathophysiologic conditions. Outside of cells, adenosine and ATP act as physiologic regulators of cells, tissues, and organs. In the heart, extracellular adenosine and ATP exert pronounced inotropic, lusitropic, electrophysiologic, and metabolic effects, which are mediated by specific cell surface receptors. In addition, both compounds can modulate sympathetic and parasympathetic input to the heart by interacting with neural elements within and without the heart, thereby modulating autonomic neural control of cardiac functions. This article briefly reviews these indirect, neurally-mediated actions of adenosine and ATP.