Features of Optical Mapping in Blue-Green and NIR Lights in Rabbit Heart

Abstract

Optical signal is the image created from the propagating electrical signal. Due to optical features (absorption, scattering, etc.) of the heart tissue the coincidence between optical and electrical action potentials (APs) is moderate. Having electrical action potentials recorded transmurally, we aimed to evaluate contribution of the electrical and the optical features on OAP upstroke formation using blue-green and near-infrared (NIR) lights. Here we introduce a new approach in analysis of the electrical activity from the optical mapping (OM) studies by recording transmural-APs with glass-microelectrodes and comparing them with the OAP, obtained using blue-green (di-4-ANEPPS) and NIR (di-4-ANBDQBS) dyes in Langendorff-perfused rabbit heart under atrial/endo-/epicardial pacing. We used averaged upstroke of transmural-APs for isolation of electrical and optical (of dye/tissue) impacts influencing formation of OAP upstroke shape, and this had helped to split the OAP upstroke into components (depth-weighted and lateral-scattering). These components separately reflect the transmural and the parallel to the epicardium electrical propagating wave. In addition, to calculate depth-weighted component, we used the probing-depth constant for fluorescence measurement that was detected directly during the OM experiment, but not from separate measurements of the excitation and the emission light penetration. The detected probing-depth constant (k) for the NIR dye was ∼2 mm, while that magnitude was about twice smaller for the blue-green dye. The results of the study open a new opportunity for the future investigations of the electrical impulse propagation in the heart.This research was funded by the European Social Fund under the Global Grant measure.