title: Suppression of ANP secretion by somatostatin through somatostatin receptor type 2.
abstract: Somatostatin is a cyclic-14 amino acid peptide which mainly distributed in digestive system and brain. Somatostatin receptor (SSTR) is a G-protein coupled receptor and all five SSTR subtypes are expressed in cardiomyocytes. The aim of this study was to investigate the effect of somatostatin on atrial natriuretic peptide (ANP) secretion and its signaling pathway. Somatostatin (0.01 and 0.1nM) decreased ANP secretion in isolated beating rat atrium in a dose-dependent manner. But atrial contractility and translocation of extracellular fluid were not changed. Somatostatin-induced decrease in ANP secretion was significantly attenuated by the pretreatment with CYN 154806 (SSTR type 2 antagonist; 0.1μM), but not by BIM 23056 (SSTR type 5 antagonist; 0.1μM) and urantide (urotensin II receptor antagonist; 0.1μM). When pretreated with an agonist for SSTR type 2 (Seglitide, 0.1nM) and SSTR type 5 (L 817818, 0.1nM), only Seglitide reduced ANP secretion similar to that of somatostatin. The suppressive effect of somatostatin on ANP secretion was attenuated by the pretreatment with an inhibitor for adenylyl cyclase (MDL-12330A, 5μM) or protein kinase A (KT 5720, 0.1μM). In diabetic rat atria, the suppressive effect of somatostatin on ANP secretion and concentration was attenuated. Real time-PCR and western blot shows the decreased level of SSTR type 2 mRNA and protein in diabetic rat atria. These data suggest that somatostatin decreased ANP secretion through SSTR type 2 and an attenuation of suppressive effect of somatostatin on ANP secretion in diabetic rat atria is due to a down-regulation of SSTR type 2.
authors.affiliation: Department of Physiology, Research Institute for Endocrine Sciences, Chonbuk National University Medical School, 2-20 Keum-Am-Dong-San, Jeonju 561-180, Republic of Korea.
authors.forename: Shan
authors.initials: S
authors.lastname: Gao
authors.forename: Young-bin
authors.initials: YB
authors.lastname: Oh
authors.forename: Amin
authors.initials: A
authors.lastname: Shah
authors.forename: Woo Hyun
authors.initials: WH
authors.lastname: Park
authors.forename: Suhn Hee
authors.initials: SH
authors.lastname: Kim
mesh_terms: D000818:Animals; D016275:Atrial Function / Q000187:drug effects*; D009320:Atrial Natriuretic Factor / Q000037:antagonists & inhibitors / Q000378:metabolism; D015153:Blotting, Western; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000503:physiopathology; D045604:Extracellular Fluid / Q000187:drug effects; D006325:Heart Atria / Q000187:drug effects / Q000378:metabolism; D006439:Hemodynamics / Q000187:drug effects; D007097:Imines / Q000494:pharmacology; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects* / Q000502:physiology; D009842:Oligopeptides / Q000494:pharmacology; D009924:Organ Culture Techniques; D010456:Peptides, Cyclic / Q000494:pharmacology; D016133:Polymerase Chain Reaction; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D017481:Receptors, Somatostatin / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013004:Somatostatin / Q000037:antagonists & inhibitors / Q000494:pharmacology*
chemical_list: C403089:CYN 154806; D007097:Imines; D009842:Oligopeptides; D010456:Peptides, Cyclic; D047428:Protein Kinase Inhibitors; D012333:RNA, Messenger; D017481:Receptors, Somatostatin; D013004:Somatostatin; C040968:seglitide; C014925:RMI 12330A; D009320:Atrial Natriuretic Factor; C093733:somatostatin receptor 2; D017868:Cyclic AMP-Dependent Protein Kinases