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Optical and electrical recordings from isolated coronary-perfused ventricular wedge preparations.

ABSTRACT: The electrophysiological heterogeneity that exists across the ventricular wall in the mammalian heart has long been recognized, but remains an area that is incompletely understood. Experimental studies of the mechanisms of arrhythmogenesis in the whole heart often examine the epicardial surface in isolation and thereby disregard transmural electrophysiology. Significant heterogeneity exists in the electrophysiological properties of cardiomyocytes isolated from different layers of the ventricular wall, and given that regional heterogeneities of membrane repolarization properties can influence the electrophysiological substrate for re-entry, the diversity of cell types and characteristics spanning the ventricular wall is important in the study of arrhythmogenesis. For these reasons, coronary-perfused left ventricular wedge preparations have been developed to permit the study of transmural electrophysiology in the intact ventricle. Since the first report by Yan and Antzelevitch in 1996, electrical recordings from the transmural surface of canine wedge preparations have provided a wealth of data regarding the cellular basis for the electrocardiogram, the role of transmural heterogeneity in arrhythmogenesis, and differences in the response of the different ventricular layers to drugs and neurohormones. Use of the wedge preparation has since been expanded to other species and more recently it has also been widely used in optical mapping studies. The isolated perfused wedge preparation has become an important tool in cardiac electrophysiology. In this review, we detail the methodology involved in recording both electrical and optical signals from the coronary-perfused wedge preparation and review the advances in cardiac electrophysiology achieved through study of the wedge.

SUBMITTER: Di Diego JM

PROVIDER: S-EPMC3535682 | biostudies-literature | 2013 Jan

REPOSITORIES: biostudies-literature

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Optical and electrical recordings from isolated coronary-perfused ventricular wedge preparations.

Di Diego José M JM Sicouri Serge S Myles Rachel C RC Burton Francis L FL Smith Godfrey L GL Antzelevitch Charles C Antzelevitch Charles C

Journal of molecular and cellular cardiology 20121109

The electrophysiological heterogeneity that exists across the ventricular wall in the mammalian heart has long been recognized, but remains an area that is incompletely understood. Experimental studies of the mechanisms of arrhythmogenesis in the whole heart often examine the epicardial surface in isolation and thereby disregard transmural electrophysiology. Significant heterogeneity exists in the electrophysiological properties of cardiomyocytes isolated from different layers of the ventricular ...[more]

PMID: 23142540

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Project description:The zebrafish (Danio rerio) has emerged as an important model for developmental cardiovascular (CV) biology; however, little is known about the cardiac function of the adult zebrafish enabling it to be used as a model of teleost CV biology. Here, we describe electrophysiological parameters, such as heart rate (HR), action potential duration (APD), and atrioventricular (AV) delay, in the zebrafish heart over a range of physiological temperatures (18-28°C). Hearts were isolated and incubated in a potentiometric dye, RH-237, enabling electrical activity assessment in several distinct regions of the heart simultaneously. Integration of a rapid thermoelectric cooling system facilitated the investigation of acute changes in temperature on critical electrophysiological parameters in the zebrafish heart. While intrinsic HR varied considerably between fish, the ex vivo preparation exhibited impressively stable HRs and sinus rhythm for more than 5 h, with a mean HR of 158 ± 9 bpm (means ± SE; n = 20) at 28°C. Atrial and ventricular APDs at 50% repolarization (APD50) were 33 ± 1 ms and 98 ± 2 ms, respectively. Excitation originated in the atrium, and there was an AV delay of 61 ± 3 ms prior to activation of the ventricle at 28°C. APD and AV delay varied between hearts beating at unique HRs; however, APD and AV delay did not appear to be statistically dependent on intrinsic basal HR, likely due to the innate beat-to-beat variability within each heart. As hearts were cooled to 18°C (by 1°C increments), HR decreased by ~40%, and atrial and ventricular APD50 increased by a factor of ~3 and 2, respectively. The increase in APD with cooling was disproportionate at different levels of repolarization, indicating unique temperature sensitivities for ion currents at different phases of the action potential. The effect of temperature was more apparent at lower levels of repolarization and, as a whole, the atrial APD was the cardiac parameter most affected by acute temperature change. In conclusion, this study describes a preparation enabling the in-depth analysis of transmembrane potential dynamics in whole zebrafish hearts. Because the zebrafish offers some critical advantages over the murine model for cardiac electrophysiology, optical mapping studies utilizing zebrafish offer insightful information into the understanding and treatment of human cardiac arrhythmias, as well as serving as a model for other teleosts.

Project description:BackgroundElectrical slow waves drive peristaltic contractions in the stomach and facilitate gastric emptying. In gastroparesis and other disorders associated with altered gastric emptying, motility defects have been related to altered slow wave frequency and disordered propagation. Experimental and clinical measurements of slow waves are made with extracellular or abdominal surface recording.MethodsWe tested the consequences of muscle contractions and movement on biopotentials recorded from murine gastric muscles with array electrodes and pairs of silver electrodes.Key resultsPropagating biopotentials were readily recorded from gastric sheets composed of the entire murine stomach. The biopotentials were completely blocked by nifedipine (2 μmol L(-1) ) that blocked contractile movements and peristaltic contractions. Wortmannin, an inhibitor of myosin light chain kinase, also blocked contractions and biopotentials. Stimulation of muscles with carbachol increased the frequency of biopotentials in control conditions but failed to elicit biopotentials with nifedipine or wortmannin present. Intracellular recording with microelectrodes showed that authentic gastric slow waves occur at a faster frequency typically than biopotentials recorded with extracellular electrodes, and electrical slow waves recorded with intracellular electrodes were unaffected by suppression of movement. Electrical transients, equal in amplitude to biopotentials recorded with extracellular electrodes, were induced by movements produced by small transient stretches (<1 mm) of paralyzed or formalin fixed gastric sheets.Conclusions & inferencesThese data demonstrate significant movement artifacts in extracellular recordings of biopotentials from murine gastric muscles and suggest that movement suppression should be an obligatory control when monitoring electrical activity and characterizing propagation and coordination of electrical events with extracellular recording techniques.

Dataset Information

Optical and electrical recordings from isolated coronary-perfused ventricular wedge preparations.

Publications

Optical and electrical recordings from isolated coronary-perfused ventricular wedge preparations.

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