title: Venous dilator effect of apelin, an endogenous peptide ligand for the orphan APJ receptor, in conscious rats.
abstract: Apelin is an endogenous depressor peptide for the G protein-coupled APJ receptor. Our hypothesis is that apelin is a venodilator, and it reduces mean circulatory filling pressure (MCFP; index of venous tone). Dose-response curves of apelin (10, 20 and 40 nmol/kg) or vehicle (0.9% NaCl) were constructed in two groups each of conscious, unrestrained rats: unblocked rats and rats pretreated with mecamylamine (Mec; ganglionic blocker) and noradrenaline (NA; to restore vascular tone). The vehicle had no effects in the unblocked or ganglionic-blocked rats. Apelin decreased mean arterial pressure (MAP) and increased heart rate (HR), but it did not alter mean circulatory filling pressure in the unblocked rats. In the ganglionic-blocked rats, apelin did not alter heart rate but decreased mean arterial pressure and mean circulatory filling pressure. These results show that apelin is an arterial and venous dilator in vivo. The depressor effect of apelin is accompanied by tachycardia which is abolished by ganglion blockade.
authors.affiliation: Department of Pharmacology and Therapeutics, Faculty of Medicine, University of British Columbia, 2176 Health Sciences Mall, Vancouver, BC, Canada V6T 1Z3.
authors.forename: Xing
authors.initials: X
authors.lastname: Cheng
authors.forename: Xiao Shuo
authors.initials: XS
authors.lastname: Cheng
authors.forename: Catherine C Y
authors.initials: CC
authors.lastname: Pang
mesh_terms: D000818:Animals; D000073861:Apelin; D000075244:Apelin Receptors; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D002352:Carrier Proteins / Q000494:pharmacology* / Q000502:physiology; D003243:Consciousness / Q000187:drug effects* / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D036341:Intercellular Signaling Peptides and Proteins; D008024:Ligands; D008297:Male; D010455:Peptides / Q000494:pharmacology / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D043562:Receptors, G-Protein-Coupled / Q000819:agonists / Q000502:physiology*; D014664:Vasodilation / Q000187:drug effects* / Q000502:physiology
chemical_list: D000073861:Apelin; D000075244:Apelin Receptors; C498579:Apln protein, rat; C491284:Aplnr protein, rat; D002352:Carrier Proteins; D036341:Intercellular Signaling Peptides and Proteins; D008024:Ligands; D010455:Peptides; D043562:Receptors, G-Protein-Coupled