[Role of novel G-protein-coupled receptors and their ligands in the cardiovascular system].
INTRODUCTION: Despite current drug therapies, cardiovascular disease remains the major cause of morbidity and mortality, which suggests that yet unknown transmitter systems might be also involved in this disease. AIMS: Recent years discoveries have mainly focused on the most common type of cardiac receptors--the seven-transmembrane-spanning G-protein coupled receptors. mRNA encoding several recently discovered, orphan' receptors and their putative ligands has been identified in human tissues such as heart, vessels and plasma. RESULTS: Data obtained from in vitro pharmacological studies using healthy and pathological surgical samples of human arteries, veins and heart muscle as well as from subsequent in vivo studies are proving advantageous in characterization of potent vasoactive and direct cardiac effects of these peptide ligands, such as apelin, relaxin, ghrelin, and urotensin II. These novel peptides also have a clinical relevance as they are shown to be differentially expressed in human heart failure. CONCLUSIONS: The pharmacological characterization of these emerging peptide-receptor systems is therefore a tantalizing area of cardiovascular research, with the prospect of identifying new diagnostic and therapeutic targets.