title: Local Field Fluorescence Microscopy: Imaging Cellular Signals in Intact Hearts.
abstract: In the heart, molecular signaling studies are usually performed in isolated myocytes. However, many pathological situations such as ischemia and arrhythmias can only be fully understood at the whole organ level. Here, we present the spectroscopic technique of local field fluorescence microscopy (LFFM) that allows the measurement of cellular signals in the intact heart. The technique is based on a combination of a Langendorff perfused heart and optical fibers to record fluorescent signals. LFFM has various applications in the field of cardiovascular physiology to study the heart under normal and pathological conditions. Multiple cardiac variables can be monitored using different fluorescent indicators. These include cytosolic [Ca2+], intra-sarcoplasmic reticulum [Ca2+] and membrane potentials. The exogenous fluorescent probes are excited and the emitted fluorescence detected with three different arrangements of LFFM epifluorescence techniques presented in this paper. The central differences among these techniques are the type of light source used for excitation and on the way the excitation light is modulated. The pulsed LFFM (PLFFM) uses laser light pulses while continuous wave LFFM (CLFFM) uses continuous laser light for excitation. Finally, light-emitting diodes (LEDs) were used as a third light source. This non-coherent arrangement is called pulsed LED fluorescence microscopy (PLEDFM).
authors.affiliation: School of Natural Sciences, University of California, Merced.
authors.forename: Yuriana
authors.initials: Y
authors.lastname: Aguilar-Sanchez
authors.affiliation: Centro de Investigaciones Cardiovasculares, Universidad de la Plata and Conicet; Facultad de Ingenieria, Universidad Nacional de Entre Rios.
authors.forename: Diego
authors.initials: D
authors.lastname: Fainstein
authors.affiliation: Department of Physiology, Midwestern University.
authors.forename: Rafael
authors.initials: R
authors.lastname: Mejia-Alvarez
authors.affiliation: School of Engineering, University of California, Merced; aescobar4@ucmerced.edu.
authors.forename: Ariel L
authors.initials: AL
authors.lastname: Escobar
mesh_terms: D000818:Animals; D001145:Arrhythmias, Cardiac / Q000175:diagnosis* / Q000378:metabolism; D020013:Calcium Signaling; D004195:Disease Models, Animal; D051379:Mice; D008856:Microscopy, Fluorescence / Q000379:methods*; D032383:Myocytes, Cardiac / Q000378:metabolism / Q000473:pathology*; D012519:Sarcoplasmic Reticulum / Q000378:metabolism / Q000473:pathology