title: Mimicking the cardiac cycle in intact cardiomyocytes using diastolic and systolic force clamps; measuring power output.
abstract: A single isolated cardiomyocyte is the smallest functional unit of the heart. Yet, all single isolated cardiomyocyte experiments have been limited by the lack of proper methods that could reproduce a physiological cardiac cycle. We aimed to investigate the contractile properties of a single cardiomyocyte that correctly mimic the cardiac cycle.
  
  
  
  By adjusting the parameters of the feedback loop, using a suitably engineered feedback system and recording the developed force and the length of a single rat cardiomyocyte during contraction and relaxation, we were able to construct force-length (FL) relations analogous to the pressure-volume (PV) relations at the whole heart level. From the cardiac loop graphs, we obtained, for the first time, the power generated by one single cardiomyocyte.
  
  
  
  Here, we introduce a new approach that by combining mechanics, electronics, and a new type optical force transducer can measure the FL relationship of a single isolated cardiomyocyte undergoing a mechanical loop that mimics the PV cycle of a beating heart.
authors.affiliation: Department of Physiology, VU University Medical Center, Institute for Cardiovascular Research (ICaR-VU), van der Boechorststraat 7, 1081 BT Amsterdam, The Netherlands IonOptix Llc., Milton, MA, USA.
authors.forename: Michiel
authors.initials: M
authors.lastname: Helmes
authors.affiliation: Department of Physiology, VU University Medical Center, Institute for Cardiovascular Research (ICaR-VU), van der Boechorststraat 7, 1081 BT Amsterdam, The Netherlands ICIN-Netherlands Heart Institute, Utrecht, The Netherlands.
authors.forename: Aref
authors.initials: A
authors.lastname: Najafi
authors.affiliation: IonOptix Llc., Milton, MA, USA.
authors.forename: Bradley M
authors.initials: BM
authors.lastname: Palmer
authors.affiliation: Biophotonics and Medical Imaging and Laserlab, VU University Amsterdam, Amsterdam, The Netherlands Optics11 BV, Amsterdam, The Netherlands.
authors.forename: Ernst
authors.initials: E
authors.lastname: Breel
authors.affiliation: Optics11 BV, Amsterdam, The Netherlands.
authors.forename: Niek
authors.initials: N
authors.lastname: Rijnveld
authors.affiliation: Biophotonics and Medical Imaging and Laserlab, VU University Amsterdam, Amsterdam, The Netherlands.
authors.forename: Davide
authors.initials: D
authors.lastname: Iannuzzi
authors.affiliation: Department of Physiology, VU University Medical Center, Institute for Cardiovascular Research (ICaR-VU), van der Boechorststraat 7, 1081 BT Amsterdam, The Netherlands ICIN-Netherlands Heart Institute, Utrecht, The Netherlands j.vandervelden@vumc.nl.
authors.forename: Jolanda
authors.initials: J
authors.lastname: van der Velden
mesh_terms: D000465:Algorithms; D000818:Animals; D003971:Diastole; D004867:Equipment Design; D025461:Feedback, Physiological; D005336:Fiber Optic Technology; D007368:Interferometry; D040542:Mechanotransduction, Cellular; D008904:Miniaturization; D032383:Myocytes, Cardiac / Q000502:physiology*; D051381:Rats; D012815:Signal Processing, Computer-Assisted; D013599:Systole; D013997:Time Factors; D014160:Transducers, Pressure
keywords: Cardiomyocyte function; Force–length relation; Microtechnology