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Single-Cell Biophysics: Measurement, Modulation, and Modeling
Poster Abstracts
75
61-POS
Board 31
Dual-Component Voltage Sensitivity of Indocyanine Green Fluorescence in the Heart
Regina Macianskiene
, Mante Almanaityte, Rimantas Treinys, Antanas Navalinskas, Rimantas
Benetis, Jonas Jurevicius.
Lithuanian University of Health Sciences, Kaunas, Lithuania.
Background
: Voltage-sensitive fluorescent dyes (VSDs) have been used in heart
electrophysiological studies for over 30 years. Nevertheless, to date, VSDs have not yet been
approved for clinical use. It was reported that the widely used fluorescent dye indocyanine green
(ICG), which has FDA approval, exhibits voltage sensitivity in various tissues.
Objective: The aim of this study was to explore the possibility of using ICG to monitor cardiac
electrical activity.
Methods
: A standard glass microelectrode and optical mapping, using a near-infrared ICG
fluorescent dye, were used to simultaneously record electrical action potential (AP) and optical
signal (OS) in a Langendorff-perfused rabbit heart that was fully stopped.
Results
: We showed the first successful detection of voltage sensitivity of the ICG dye in a heart.
The ICG OS is not caused by contraction or by Ca2+ transients, and reliably follows the AP
changes induced by pharmacological compounds. The ICG OS has a dual-component (fast and
slow) response to membrane potential changes that accurately tracks the time of electrical signal
propagation but clearly differ in their kinetics and voltage-sensitive spectral properties. The
voltage-sensitive fluorescence of ICG dye was not high relative to the fluorescence of standard
VSDs. However, after averaging, the good signal-to-noise ratio (> 20 dB) of ICG rendered its
signal suitable for observing cardiac electrical activity.
Conclusions
: Our research confirms that ICG is a voltage-sensitive dye with a dual-component
(fast and slow) response to membrane potential changes. We suggest that it can be used as a tool
for examining excitation wave propagation in the heart.
This research was funded by a grant (No.SEN-15/2015) from the Research Council of Lithuania.