Current View on Autonomic System Receptors in the Heart

Overview

Heart function reflects activity of the heart pacemaker cells. This basic function is permanently influenced by two practically antagonistic systems - sympathetic and parasympathetic systems. They control not only the force of contraction (influencing calcium channels), heart rate (via potassium channels), but also arterioventricular transduction (changing the threshold for ion channels opening by influencing the maximal negative level of the membrane potential). Last few years changed our view on autonomic receptor expression in the heart. It is assumed that the heart adrenoreceptors are represented by a1, b, and b2 subtypes. The expression of b3 subtype is still controversial, similary the existence of other, fourth b-adrenoreceptor subtype, putative b4, is uncertain. Moreover, the end of the twentieth century brought the correction of former idea about a single muscarinic receptor subtype (M2) in the heart. Functional correlates of these findings are also reviewed.

Key words:
heart, sympathetic nervous system, parasympathetic nervous system, muscarinic receptors, adrenoreceptors