Fluorescence imaging of electrical activity in cardiac cells using an all-solid-state system.
Tracking spatial and temporal determinants of cardiac arrhythmogenesis at the cellular level presents challenges to the optical mapping techniques employed. In this paper, we describe a compact system combining two nontraditional low-cost solutions for excitation light sources and emission filters in fluorescence measurements of transmembrane potentials, Vm, or intracellular calcium, [Ca2+]i in cardiac cell networks. This is the first reported use of high-power blue and green light emitting diodes (LEDs), to excite cell monolayers stained with Vm - (di-8-ANEPPS) or [Ca2+]i - (Fluo-3) sensitive dyes. In addition, we use simple techniques for fabrication of suitable thin emission filters with uniform properties, no auto-fluorescence, high durability and good flexibility for imaging Vm or [Ca2+]i. The battery-operated LEDs and the fabricated emission filters, integrated with a fiber-optic system for contact fluorescence imaging, were used as tools to characterize conduction velocity restitution at the macro-scale. The versatility of the LEDs for illumination is further emphasized through 1) demonstration of their usage for epi-illumination recordings at the single-cell level, and 2) demonstration of their unique high-frequency light modulation ability. The LEDs showed excellent stability as excitation light sources for fluorescence measurements; acceptable signal-to-noise ratio and negligible cell photodamage and indicator dye photobleaching were observed.
Entcheva
Emilia
E
Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD 21250, USA. emilia.entcheva@sunysb.edu
Kostov
Yordan
Y
Tchernev
Elko
E
Tung
Leslie
L
D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D000831:Animals, Newborn; D020013:Calcium Signaling / Q000502:physiology*; D002478:Cells, Cultured; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005456:Fluorescent Dyes; D006329:Heart Conduction System / Q000502:physiology*; D006352:Heart Ventricles / Q000166:cytology; D008564:Membrane Potentials / Q000502:physiology*; D008856:Microscopy, Fluorescence / Q000295:instrumentation* / Q000379:methods; D032383:Myocytes, Cardiac / Q000166:cytology* / Q000502:physiology*; D009431:Neural Conduction / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012666:Semiconductors; D013050:Spectrometry, Fluorescence / Q000295:instrumentation* / Q000379:methods; D016276:Ventricular Function
D005456:Fluorescent Dyes