title: Contractility Measurements on Isolated Papillary Muscles for the Investigation of Cardiac Inotropy in Mice.
abstract: Papillary muscle isolated from adult mouse hearts can be used to study cardiac contractility during different physiological/pathological conditions. The contractile characteristics can be evaluated independently of external influences such as vascular tonus or neurohumoral status. It depicts a scientific approach between single cell measurements with isolated cardiac myocytes and in vivo studies like echocardiography. Thus, papillary muscle preparations serve as an excellent model to study cardiac physiology/pathophysiology and can be used for investigations like the modulation by pharmacological agents or the exploration of transgenic animal models. Here, we describe a method of isolating the murine left anterior papillary muscle to investigate cardiac contractility in an organ bath setup. In contrast to a muscle strip preparation isolated from the ventricular wall, the papillary muscle can be prepared in toto without damaging the muscle tissue severely. The organ bath setup consists of several temperature-controlled, gassed and electrode-equipped organ bath chambers. The isolated papillary muscle is fixed in the organ bath chamber and electrically stimulated. The evoked twitch force is recorded using a pressure transducer and parameters such as twitch force amplitude and twitch kinetics are analyzed. Different experimental protocols can be performed to investigate the calcium- and frequency-dependent contractility as well as dose-response curves of contractile agents such as catecholamines or other pharmaceuticals. Additionally, pathologic conditions like acute ischemia can be simulated.
authors.affiliation: Pharmakologisches Institut, Universität Heidelberg.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Uhl
authors.affiliation: Pharmakologisches Institut, Universität Heidelberg.
authors.forename: Marc
authors.initials: M
authors.lastname: Freichel
authors.affiliation: Pharmakologisches Institut, Universität Heidelberg; ilka.mathar@pharma.uni-heidelberg.de.
authors.forename: Ilka
authors.initials: I
authors.lastname: Mathar
mesh_terms: D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism; D004558:Electric Stimulation; D000067268:Isolated Heart Preparation / Q000379:methods*; D051379:Mice; D009200:Myocardial Contraction / Q000502:physiology*; D032383:Myocytes, Cardiac / Q000378:metabolism / Q000502:physiology; D010210:Papillary Muscles / Q000187:drug effects / Q000378:metabolism / Q000502:physiology* / Q000601:surgery; D015398:Signal Transduction
chemical_list: D000318:Adrenergic beta-Agonists; D002118:Calcium