title: Voltage-Sensitive Fluorescence of Indocyanine Green in the Heart.
abstract: So far, the optical mapping of cardiac electrical signals using voltage-sensitive fluorescent dyes has only been performed in experimental studies because these dyes are not yet approved for clinical use. It was recently reported that the well-known and widely used fluorescent dye indocyanine green (ICG), which has FDA approval, exhibits voltage sensitivity in various tissues, thus raising hopes that electrical activity could be optically mapped in the clinic. The aim of this study was to explore the possibility of using ICG to monitor cardiac electrical activity. Optical mapping experiments were performed on Langendorff rabbit hearts stained with ICG and perfused with electromechanical uncouplers. The residual contraction force and electrical action potentials were recorded simultaneously. Our research confirms that ICG is a voltage-sensitive dye with a dual-component (fast and slow) response to membrane potential changes. The fast component of the optical signal (OS) can have opposite polarities in different parts of the fluorescence spectrum. In contrast, the polarity of the slow component remains the same throughout the entire spectrum. Separating the OS into these components revealed two different voltage-sensitivity mechanisms for ICG. The fast component of the OS appears to be electrochromic in nature, whereas the slow component may arise from the redistribution of the dye molecules within or around the membrane. Both components quite accurately track the time of electrical signal propagation, but only the fast component is suitable for estimating the shape and duration of action potentials. Because ICG has voltage-sensitive properties in the entire heart, we suggest that it can be used to monitor cardiac electrical behavior in the clinic.
authors: Lithuanian University of Health Sciences, Kaunas, Lithuania.
authors: Irma
authors: I
authors: Martišienė
authors: Lithuanian University of Health Sciences, Kaunas, Lithuania. Electronic address: regina.macianskiene@lsmuni.lt.
authors: Regina
authors: R
authors: Mačianskienė
authors: Lithuanian University of Health Sciences, Kaunas, Lithuania.
authors: Rimantas
authors: R
authors: Treinys
authors: Lithuanian University of Health Sciences, Kaunas, Lithuania.
authors: Antanas
authors: A
authors: Navalinskas
authors: Lithuanian University of Health Sciences, Kaunas, Lithuania.
authors: Mantė
authors: M
authors: Almanaitytė
authors: Lithuanian University of Health Sciences, Kaunas, Lithuania.
authors: Dainius
authors: D
authors: Karčiauskas
authors: Lithuanian University of Health Sciences, Kaunas, Lithuania.
authors: Audrius
authors: A
authors: Kučinskas
authors: Lithuanian University of Health Sciences, Kaunas, Lithuania.
authors: Ramunė
authors: R
authors: Grigalevičiūtė
authors: Lithuanian University of Health Sciences, Kaunas, Lithuania.
authors: Vilma
authors: V
authors: Zigmantaitė
authors: Lithuanian University of Health Sciences, Kaunas, Lithuania.
authors: Rimantas
authors: R
authors: Benetis
authors: Lithuanian University of Health Sciences, Kaunas, Lithuania.
authors: Jonas
authors: J
authors: Jurevičius
mesh_terms: D000200:Action Potentials; D000818:Animals; D005456:Fluorescent Dyes; D006321:Heart / Q000502:physiology*; D007208:Indocyanine Green; D011817:Rabbits; D056969:Voltage-Sensitive Dye Imaging / Q000379:methods*
chemical_list: D005456:Fluorescent Dyes; D007208:Indocyanine Green