Abstract
Regulation of heart function during physiological and/or pathological stresses occurs via numerous cellular signal transduction systems. Since there are a limited number of second messengers, these pathways are spatially and temporally compartmentalized resulting in tightly controlled localized signaling. In ventricular myocytes, prominent signaling cascades occur through G-protein coupled receptors (GPCRs) with the β-adrenergic (β-AR) and endothelin pathways being two important illustrations.