Single-Cell Biophysics: Measurement, Modulation, and Modeling

Single-Cell Biophysics: Measurement, Modulation, and Modeling

Poster Abstracts

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.

75