[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"detail-sidebar-cat-0-en-105":3,"doc-seo-461814-105":59,"doc-detail-461814-en":130},{"code":4,"msg":5,"data":6},0,"success",[7,13,18,23,28,33,38,43,48,51,55],{"id":8,"doc_module":4,"doc_module_name":9,"category_name":10,"show_sort_weight":11,"slug":12},1,"Document","Story & Novel",90,"story-novel",{"id":14,"doc_module":4,"doc_module_name":9,"category_name":15,"show_sort_weight":16,"slug":17},2,"Literature",80,"literature",{"id":19,"doc_module":4,"doc_module_name":9,"category_name":20,"show_sort_weight":21,"slug":22},4,"Exam",70,"exam",{"id":24,"doc_module":4,"doc_module_name":9,"category_name":25,"show_sort_weight":26,"slug":27},5,"Comic",60,"comic",{"id":29,"doc_module":4,"doc_module_name":9,"category_name":30,"show_sort_weight":31,"slug":32},6,"Technology",50,"technology",{"id":34,"doc_module":4,"doc_module_name":9,"category_name":35,"show_sort_weight":36,"slug":37},7,"Healthcare",40,"healthcare",{"id":39,"doc_module":4,"doc_module_name":9,"category_name":40,"show_sort_weight":41,"slug":42},8,"Research & Report",30,"research-report",{"id":44,"doc_module":4,"doc_module_name":9,"category_name":45,"show_sort_weight":46,"slug":47},9,"Religion & Spirituality",20,"religion-spirituality",{"id":46,"doc_module":4,"doc_module_name":9,"category_name":49,"show_sort_weight":46,"slug":50},"World Cup","world-cup",{"id":52,"doc_module":4,"doc_module_name":9,"category_name":53,"show_sort_weight":52,"slug":54},10,"Lifestyle","lifestyle",{"id":56,"doc_module":4,"doc_module_name":9,"category_name":57,"show_sort_weight":24,"slug":58},19,"General","general",{"code":4,"msg":60,"data":61},"ok",{"site_id":62,"language":63,"slug":64,"title":65,"keywords":66,"description":67,"schema_data":68,"social_meta":123,"head_meta":125,"extra_data":127,"updated_unix":129},105,"en","contractile-effects-of-glucagon-in-mouse-cardiac-preparations","Contractile Effects of Glucagon in Mouse Cardiac Preparations","","Glucagon, an endogenous pancreatic peptide, increases beating rate in cultured rat neonatal cardiomyocytes and in isolated rat right atrial preparations, and can elevate heart rate in living adult mice. The study tests whether glucagon’s in vivo effects in adult mice arise from central versus direct cardiac glucagon receptor actions. Isolated paced atria and Langendorff-perfused whole hearts were used to measure chronotropy and contractility. Glucagon produced time- and concentration-dependent positive chronotropic effects in right atria via glucagon receptors, involving HCN channels. It reduced right atrial force, did not affect left atrial force, and increased beating rate but reduced left ventricular force in whole hearts. Receptor gene expression was lowest in left atrium, higher in ventricle, and highest in right atrium.",{"@graph":69,"@context":122},[70,84,105],{"@type":71,"itemListElement":72},"BreadcrumbList",[73,77,79,82],{"item":74,"name":75,"@type":76,"position":8},"https://docshare.wps.com","Home","ListItem",{"item":78,"name":9,"@type":76,"position":14},"https://docshare.wps.com/document/",{"item":80,"name":35,"@type":76,"position":81},"https://docshare.wps.com/document/healthcare/",3,{"item":83,"name":65,"@type":76,"position":19},"https://docshare.wps.com/document/contractile-effects-of-glucagon-in-mouse-cardiac-preparations/461814/",{"url":83,"name":65,"@type":85,"image":86,"author":91,"headline":65,"publisher":94,"fileFormat":97,"inLanguage":63,"description":67,"dateModified":98,"datePublished":99,"encodingFormat":97,"isAccessibleForFree":100,"interactionStatistic":101},"DigitalDocument",{"url":87,"@type":88,"width":89,"height":90},"https://docshare.wps.com/thumbnails/contractile-effects-of-glucagon-in-mouse-cardiac-preparations/461814.png","ImageObject",300,407,{"name":92,"@type":93},"Patrick","Person",{"url":74,"name":95,"@type":96},"DocShare","Organization","application/pdf","2026-10-31","2026-09-30",true,{"@type":102,"interactionType":103,"userInteractionCount":56},"InteractionCounter",{"@type":104},"ViewAction",{"@type":106,"mainEntity":107},"FAQPage",[108,114,118],{"name":109,"@type":110,"acceptedAnswer":111},"What hypothesis did the study test about glucagon’s effects in adult mice?","Question",{"text":112,"@type":113},"The study tested whether glucagon exerts a direct positive chronotropic effect on the adult mouse heart via cardiac glucagon receptors, rather than solely through central glucagon receptors.","Answer",{"name":115,"@type":110,"acceptedAnswer":116},"How were glucagon effects measured in the experiments?",{"text":117,"@type":113},"Glucagon was applied at cumulatively increasing concentrations (0.1–100 nM) to isolated paced left atrial preparations, isolated spontaneously beating right atrial preparations, and isolated spontaneously beating retrogradely perfused whole hearts.",{"name":119,"@type":110,"acceptedAnswer":120},"Which treatments modified glucagon’s positive chronotropic effects?",{"text":121,"@type":113},"Positive chronotropic effects were reversed by glucagon receptor antagonists SC203972 and desglucagon, attenuated by ivabradine (HCN channel inhibitor), and also attenuated by stimulation of A1-adenosine and muscarinic receptors.","https://schema.org",{"og:url":83,"og:type":124,"og:title":65,"og:site_name":95,"og:description":67},"article",{"robots":126,"canonical":83},"index,follow",{"doc_id":128,"site_id":62},461814,1790815519,{"code":4,"msg":5,"data":131},{"doc_id":128,"user_id":132,"nickname":92,"user_avatar":133,"doc_module":4,"category_id":34,"category_name":35,"doc_title":65,"doc_description":67,"doc_content":134,"file_id":135,"file_url":136,"file_type":137,"file_size":138,"view_count":56,"is_deleted":4,"is_public":8,"is_downloadable":8,"audit_status":8,"page_count":139,"language":140,"language_code":63,"site_id":62,"html_lang":63,"table_of_contents":141,"faqs":142,"seo_title":143,"seo_description":67,"update_tm":144,"read_time":145,"preview_page_count":4},549758146520,"https://ap-avatar.wpscdn.com/avatar/80002397d8c0411e94?_k=1775819394049821470","Article  \nContractile Effects of Glucagon in Mouse Cardiac Preparations  \nJoachim Neumann 1, *,†, Franziska Schmidt 1,†, Pauline Braekow 1, Uwe Kirchhefer 2, Jan Klimas 3, Katarina Hadova 3 and Ulrich Gergs 1  \nAcademic Editor: Anastasios Lymperopoulos  \nReceived: 22 August 2025  \nRevised: 5 December 2025  \nAccepted: 7 December 2025  \nPublished: 22 December 2025  \nCopyright: © 2025 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license.  \n1 Institute for Pharmacology and Toxicology, Medical Faculty, Martin-Luther-University Halle-Wittenberg, Magdeburger Straße 4, D-06097 Halle, Germany; [franziska.schmidt.ue@gmail.com](franziska.schmidt.ue@gmail.com) (F.S.);  \npauline.braekow@student.uni-halle.de (P.B.); [ulrich.gergs@medizin.uni-halle.de](ulrich.gergs@medizin.uni-halle.de) (U.G.)  \n2 Institute for Pharmacology and Toxicology, Medical Faculty, University Münster, Domagkstraße 12, D-48149 Münster, Germany; [kirchhef@uni-muenster.de](kirchhef@uni-muenster.de)  \n3 Department of Pharmacology and Toxicology, Faculty of Pharmacy, Comenius University in Bratislava, Odbojárov 10, SK-832 32 Bratislava, Slovakia; [jan.klimas@uniba.sk](jan.klimas@uniba.sk) (J.K.); [hadova@fpharm.uniba.sk](hadova@fpharm.uniba.sk) (K.H.)  \n* Correspondence: joachim.neumann@medizin.uni-halle.de † These authors contributed equally to this work.  \nAbstract  \nGlucagon is an endogenous peptide that is produced in the pancreas. Via glucagon receptors, glucagon increases the beating rate in cultured rat neonatal cardiomyocytes and also in isolated right atrial preparations from adult rats. Moreover, in living adult mice, injections of glucagon can elevate the heart rate. It is unknown whether these effects of glucagon in living adult mice are mediated via central glucagon receptors or via a direct effect on cardiac glucagon receptors. Thus, we tested the hypothesis that glucagon can exert a direct positive chronotropic effect in the adult mouse heart. We measured the contractile effects of cumulatively increasing concentrations of glucagon (0.1–100 nM) in isolated paced (1 Hz) left atrial preparations, in isolated spontaneously beating right atrial preparations and in isolated spontaneously beating retrogradely perfused whole hearts. We detected in isolated right atrial preparations time-and concentration-dependent positive chronotropic effects of glucagon that were reversed by the glucagon receptor antagonists SC203972 and desglucagon. The positive chronotropic effects of glucagon were also attenuated by 1 µM of ivabradine, an inhibitor of the hyperpolarization-activated cation channels (HCN), but not by 100 nM rolipram, a phosphodiesterase 4 inhibitor, nor by 10 µM of propranolol, a β-adrenoceptor antagonist. Moreover, the positive chronotropic effects of glucagon were also attenuated by stimulation of the A 1-adenosine receptor or muscarinic receptors. Glucagon decreased the force of contraction in right atrial preparations. In left atrial preparations, glucagon failed to alter the force of contraction. In isolated adult mouse hearts perfused in the Langendorff mode, 10 nM of glucagon increased the beating rate and reduced left ventricular force of contraction. The gene expression of the glucagon receptors was lowest in the left atrium, higher in the ventricle and highest in the right atrium of adult mice. In summary, glucagon exerted a positive chronotropic effect in the mouse heart via glucagon receptors, mediated, at least in part, via HCN channels in the sinus node.  \nKeywords: glucagon; atrium; Langendorff-heart; adult mouse; cardiac preparations  \n1. Introduction  \nGlucagon, a peptide comprising 29 amino acids, is produced in α-cells in pancreatic islets of Langerhans (e.g., [1]) . Glucagon acts via glucagon receptors (Figure 1, GCGR [2–6]) .  \nGCGR raises the activity of adenylyl cyclases in many tissues via stimulatory guano","cbCairA1xSQZP8O0","https://ap.wps.com/l/cbCairA1xSQZP8O0","pdf",4921295,27,"English","# Abstract\n# Keywords\n# Introduction","[{\"question\":\"What hypothesis did the study test about glucagon’s effects in adult mice?\",\"answer\":\"The study tested whether glucagon exerts a direct positive chronotropic effect on the adult mouse heart via cardiac glucagon receptors, rather than solely through central glucagon receptors.\"},{\"question\":\"How were glucagon effects measured in the experiments?\",\"answer\":\"Glucagon was applied at cumulatively increasing concentrations (0.1–100 nM) to isolated paced left atrial preparations, isolated spontaneously beating right atrial preparations, and isolated spontaneously beating retrogradely perfused whole hearts.\"},{\"question\":\"Which treatments modified glucagon’s positive chronotropic effects?\",\"answer\":\"Positive chronotropic effects were reversed by glucagon receptor antagonists SC203972 and desglucagon, attenuated by ivabradine (HCN channel inhibitor), and also attenuated by stimulation of A1-adenosine and muscarinic receptors.\"}]","Contractile Effects of Glucagon in Mouse Cardiac Preparations | PDF",1790762489,68]