Mapping action potentials and calcium transients simultaneously from the intact heart

2001 ◽  
Vol 280 (5) ◽  
pp. H2053-H2060 ◽  
Author(s):  
Kenneth R. Laurita ◽  
Ashish Singal
Keyword(s):  
Action Potentials ◽  
Cardiac Electrophysiology ◽  
Optical Mapping ◽  
Fluorescence Emission ◽  
Calcium Transients ◽  
Calcium Handling ◽  
Guinea Pig Heart ◽  
Spectral Overlap ◽  
Intact Heart

Intracellular calcium handling plays an important role in cardiac electrophysiology. Using two fluorescent indicators, we developed an optical mapping system that is capable of measuring calcium transients and action potentials at 256 recording sites simultaneously from the intact guinea pig heart. On the basis of in vitro measurements of dye excitation and emission spectra, excitation and emission filters at 515 ± 5 and >695 nm, respectively, were used to measure action potentials with di-4-ANEPPS, and excitation and emission filters at 365 ± 25 and 485 ± 5 nm, respectively, were used to measure calcium transients with indo 1. The percent error due to spectral overlap was small when action potentials were measured (1.7 ± 1.0%, n = 3) and negligible when calcium transients were measured (0%, n = 3). Recordings of calcium transients, action potentials, and isochrone maps of depolarization time and the time of calcium transient onset indicated negligible error due to fluorescence emission overlap. These data demonstrate that the error due to spectral overlap of indo 1 and di-4-ANEPPS is sufficiently small, such that optical mapping techniques can be used to measure calcium transients and action potentials simultaneously in the intact heart.

scholarly journals A Complete and Low-Cost Cardiac Optical Mapping System in Translational Animal Models

2021 ◽  
Vol 12 ◽  
Author(s):  
Manuel Marina-Breysse ◽  
Alba García-Escolano ◽  
Joaquín Vila-García ◽  
Gabriel Reale-Nosei ◽  
José M. Alfonso-Almazán ◽  
...  
Keyword(s):  
Action Potentials ◽  
Cardiac Electrophysiology ◽  
High Speed ◽  
Optical Mapping ◽  
Low Cost ◽  
Cytosolic Calcium ◽  
Calcium Transients ◽  
Spatiotemporal Resolution ◽  
Mapping System ◽  
Computer Scientists

Clinicians, biologists, physicists, engineers, and computer scientists are coming together to better understand heart disease, which is currently the leading cause of death globally. Optical mapping, a high-speed fluorescence imaging technique that visualizes and measures key cardiac parameters such as action potentials, cytosolic calcium transients, and fibrillation dynamics, is a core research tool that has arisen from such interdisciplinary collaborations. In an effort to broaden its use, especially among clinical scientists and students, we developed a complete and low-cost optical mapping system, including a constant-flow Langendorff perfusion system, which minimizes the economic threshold to widespread use of this powerful tool in cardiac electrophysiology research. The system described here provides high spatiotemporal resolution data about action potentials, intracellular calcium transients and fibrillation wave dynamics in isolated Langendorff-perfused hearts (pigs and rabbits), relevant for translational research. All system components and software elements are fully disclosed with the aim of increasing the use of this affordable and highly versatile tool among clinicians, basic scientists and students wishing to tackle their own research questions with their own customizable systems.

Intracellular calcium handling heterogeneities in intact guinea pig hearts

2004 ◽  
Vol 286 (2) ◽  
pp. H648-H656 ◽  
Author(s):  
Rodolphe P. Katra ◽  
Etienne Pruvot ◽  
Kenneth R. Laurita
Keyword(s):  
Guinea Pig ◽  
Intracellular Calcium ◽  
Calcium Release ◽  
Optical Mapping ◽  
Contractile Function ◽  
Calcium Transient ◽  
Calcium Transients ◽  
Calcium Handling ◽  
Excitation Light ◽  
Intact Heart

Regional heterogeneities of ventricular repolarizing currents and their role in arrhythmogenesis have received much attention; however, relatively little is known regarding heterogeneities of intracellular calcium handling. Because repolarization properties and contractile function are heterogeneous from base to apex of the intact heart, we hypothesize that calcium handling is also heterogeneous from base to apex. To test this hypothesis, we developed a novel ratiometric optical mapping system capable of measuring calcium fluorescence of indo-1 at two separate wavelengths from 256 sites simultaneously. With the use of intact Langendorff-perfused guinea pig hearts, ratiometric calcium transients were recorded under normal conditions and during administration of known inotropic agents. Ratiometric calcium transients were insensitive to changes in excitation light intensity and fluorescence over time. Under control conditions, calcium transient amplitude near the apex was significantly larger (60%, P < 0.01) compared with the base. In contrast, calcium transient duration was significantly longer (7.5%, P < 0.03) near the base compared with the apex. During isoproterenol (0.05 μM) and verapamil (2.5 μM) administration, ratiometric calcium transients accurately reflected changes in contractile function, and, the direction of base-to-apex heterogeneities remained unchanged compared with control. Ratiometric optical mapping techniques can be used to accurately quantify heterogeneities of calcium handling in the intact heart. Significant heterogeneities of calcium release and sequestration exist from base to apex of the intact heart. These heterogeneities are consistent with base-to-apex heterogeneities of contraction observed in the intact heart and may play a role in arrhythmogenesis under abnormal conditions.

scholarly journals Transmural Cellular Heterogeneity in Myocardial Electromechanics

2016 ◽  
Author(s):  
Anastasia Khokhlova ◽  
Nathalie Vikulova ◽  
Leonid Katsnelson ◽  
Gentaro Iribe ◽  
Olga Solovyova
Keyword(s):  
Experimental Data ◽  
Electrical Properties ◽  
Electromechanical Coupling ◽  
Cellular Heterogeneity ◽  
Calcium Handling ◽  
Normal Heart ◽  
Guinea Pig Heart ◽  
Simulation Results ◽  
Myocardial Heterogeneity ◽  
Intact Heart

Myocardial heterogeneity is an attribute of the normal heart. We have developed integrative models of cardiomyocytes from the subendocardial (ENDO) and subepicardial (EPI) ventricular regions that take into account experimental data on specific features of intracellular electromechanical coupling in the guinea pig heart. The models adequately simulate experimental data on the action potential and contraction of the ENDO and EPI cells. The modeling results predict that heterogeneity in the parameters of calcium handling and myofilament mechanics in isolated ENDO and EPI cardiomyocytes via cooperative mechanisms of mechano-calcium-electric feedback are essential to produce the differences in Ca2+ transients and contraction profiles and may further enhance transmural differences in the electrical properties between the cells. Simulation results predict that ENDO cells have greater sensitivity to changes in afterload than EPI cells. These data are important for understanding the behavior of cardiomyocytes in the intact heart.

Hyperthyroid adult rat cardiomyocytes. II. Single cell electrophysiology and free calcium transients

1989 ◽  
Vol 257 (5) ◽  
pp. C957-C963 ◽  
Author(s):  
Q. Li ◽  
Z. Guan ◽  
B. A. Biagi ◽  
B. T. Stokes ◽  
R. A. Altschuld
Keyword(s):  
Single Cell ◽  
Action Potentials ◽  
Mechanical Performance ◽  
Ventricular Myocytes ◽  
Calcium Transients ◽  
Calcium Handling ◽  
Free Calcium ◽  
Half Time ◽  
Rat Cardiomyocytes ◽  
Adult Rat

The effects of hyperthyroidism on electrophysiological properties and intracellular free calcium transients in single adult rat cardiomyocytes were studied using conventional microelectrodes and time-resolved single cell fura-2 fluorescence microscopy. Under control conditions, resting membrane potentials and triggered action potentials were not different in euthyroid and hyperthyroid myocytes. Calcium transients produced by electrical stimulation, however, were markedly abbreviated in hyperthyroid myocytes. During a train of stimuli, the duration of the calcium transients at half peak amplitude (half time) was 124 +/- 14 ms at the fifth beat in hyperthyroid cells vs. 287 +/- 35 ms in euthyroid cells. Isoproterenol (1 microM) prolonged time to 50% repolarization (APD50) of the action potentials and increased the peak calcium transients in both euthyroid and hyperthyroid myocytes. It also shortened the half time of the calcium transients in euthyroid myocytes but had little effect on the half time in hyperthyroid cells. These data are consistent with the electrophysiology and mechanical performance in intact euthyroid and hyperthyroid cardiac tissues, and the intrinsic changes in hyperthyroid tissues can therefore be illustrated in single ventricular myocytes. Furthermore, the results suggest that alterations in intracellular calcium handling by sarcoplasmic reticulum may account for contractile changes of the heart induced by hyperthyroidism.

scholarly journals Design and mechanistic insight into ultrafast calcium indicators for monitoring intracellular calcium dynamics

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Nordine Helassa ◽  
Borbala Podor ◽  
Alan Fine ◽  
Katalin Török
Keyword(s):  
Intracellular Calcium ◽  
Action Potentials ◽  
Rational Design ◽  
Calcium Transients ◽  
Calcium Dynamics ◽  
Binding Interface ◽  
Calcium Indicators ◽  
Slow Kinetics ◽  
Decay Times

Abstract Calmodulin-based genetically encoded fluorescent calcium indicators (GCaMP-s) are powerful tools of imaging calcium dynamics from cells to freely moving animals. High affinity indicators with slow kinetics however distort the temporal profile of calcium transients. Here we report the development of reduced affinity ultrafast variants of GCaMP6s and GCaMP6f. We hypothesized that GCaMP-s have a common kinetic mechanism with a rate-limiting process in the interaction of the RS20 peptide and calcium-calmodulin. Therefore we targeted specific residues in the binding interface by rational design generating improved indicators with GCaMP6f u displaying fluorescence rise and decay times (t 1/2) of 1 and 3 ms (37 °C) in vitro, 9 and 22-fold faster than GCaMP6f respectively. In HEK293T cells, GCaMP6f u revealed a 4-fold faster decay of ATP-evoked intracellular calcium transients than GCaMP6f. Stimulation of hippocampal CA1 pyramidal neurons with five action potentials fired at 100 Hz resulted in a single dendritic calcium transient with a 2-fold faster rise and 7-fold faster decay time (t 1/2 of 40 ms) than GCaMP6f, indicating that tracking high frequency action potentials may be limited by calcium dynamics. We propose that the design strategy used for generating GCaMP6f u is applicable for the acceleration of the response kinetics of GCaMP-type calcium indicators.

scholarly journals Acidosis in models of cardiac ventricular myocytes

2006 ◽  
Vol 364 (1842) ◽  
pp. 1171-1186 ◽  
Author(s):  
Edmund J Crampin ◽  
Nicolas P Smith ◽  
A. Elise Langham ◽  
Richard H Clayton ◽  
Clive H Orchard
Keyword(s):  
Cardiac Electrophysiology ◽  
Ventricular Myocytes ◽  
Ph Regulation ◽  
Respiratory Acidosis ◽  
Calcium Transients ◽  
Calcium Handling ◽  
Contraction Coupling ◽  
Complex Interactions ◽  
Experimental Findings ◽  
Impaired Cardiac Function

The effects of acidosis on cardiac electrophysiology and excitation–contraction coupling have been studied extensively. Acidosis decreases the strength of contraction and leads to altered calcium transients as a net result of complex interactions between protons and a variety of intracellular processes. The relative contributions of each of the changes under acidosis are difficult to establish experimentally, however, and significant uncertainties remain about the key mechanisms of impaired cardiac function. In this paper, we review the experimental findings concerning the effects of acidosis on the action potential and calcium handling in the cardiac ventricular myocyte, and we present a modelling study that establishes the contribution of the different effects to altered Ca 2+ transients during acidosis. These interactions are incorporated into a dynamical model of pH regulation in the myocyte to simulate respiratory acidosis in the heart.

scholarly journals Basic Concepts of Optical Mapping Techniques in Cardiac Electrophysiology

2009 ◽  
Vol 11 (2) ◽  
pp. 195-207 ◽  
Author(s):  
Mina Attin ◽  
William T. Clusin
Keyword(s):  
Membrane Potential ◽  
Cardiac Electrophysiology ◽  
Optical Mapping ◽  
Simultaneous Recording ◽  
Calcium Transients ◽  
Mapping Technique ◽  
Basic Concepts ◽  
Temporal And Spatial ◽  
Mapping Techniques ◽  
Whole Heart

Optical mapping is a tool used in cardiac electrophysiology to study the heart’s normal rhythm and arrhythmias. The optical mapping technique provides a unique opportunity to obtain membrane potential recordings with a higher temporal and spatial resolution than electrical mapping. Additionally, it allows simultaneous recording of membrane potential and calcium transients in the whole heart. This article presents the basic concepts of optical mapping techniques as an introduction for students and investigators in experimental laboratories unfamiliar with it.

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