Noninvasive technique for measurement of heartbeat regularity in zebrafish (Danio rerio) embryos

Abstract

Background: Zebrafish (Danio rerio), due to its optical accessibility and similarity to human, has emerged as model organism for cardiac research. Although various methods have been developed to assess cardiac functions in zebrafish embryos, there lacks a method to assess heartbeat regularity in blood vessels. Heartbeat regularity is an important parameter for cardiac function and is associated with cardiotoxicity in human being. Using stereomicroscope and digital video camera, we have developed a simple, noninvasive method to measure the heart rate and heartbeat regularity in peripheral blood vessels. Anesthetized embryos were mounted laterally in agarose on a slide and the caudal blood circulation of zebrafish embryo was video-recorded under stereomicroscope and the data was analyzed by custom-made software. The heart rate was determined by digital motion analysis and power spectral analysis through extraction of frequency characteristics of the cardiac rhythm. The heartbeat regularity, defined as the rhythmicity index, was determined by short-time Fourier Transform analysis.

NADPH Oxidase 4 Induces Cardiac Arrhythmic Phenotype in Zebrafish

“…Next, we measured the beat-to-beat intervals (time interval of two consecutive contractions) of each embryo. The beat-to-beat intervals of control embryos had small fluctuations as expected for normal physiology (23,24). However, NOX4-overexpressed embryos had much more variable fluctuations in beat-to-beat interval.…”

“…By injecting 300 pg of wild type hNOX4 RNA into one-cell stage myl7:GFP transgenic embryos, we discovered that 53% of these embryos developed a phenotype of irregular heart beats at 24 -30 hpf (supplemental Video I, representative videos from control or NOX4 RNAinjected embryos), although only 10% of control embryos had a phenotype of much less variable heart beats at the same developmental stage (19 out of 167), which is considered physiological (23,24). Table 1 also summarized all phenotypic responses to molecular and pharmacological interventions described below.…”

Automatic Zebrafish Heartbeat Detection and Analysis for Zebrafish Embryos

“…Up to date, an assessment of the heart rate is often practiced manually by counting heartbeats from slow motion replay of videotape recordings, what is neither practical for large numbers of hearts to be analyzed nor is it accurate when determining beat-to-beat intervals as needed for detection of arrhythmias. 7 Existing software for semiautomated analysis of heartbeats [7][8][9][10][11][12][13] has several limitations. One is that the embryos have to be anesthetized by adding Tricaine 11,14 or MS-222 12 to avoid movement of zebrafish embryos during videoing.…”

Organic Nanovesicular Cargoes for Sustained Drug Delivery: Synthesis, Vesicle Formation, Controlling “Pearling” States, and Terfenadine Loading/Release Studies

“…TFN is also known to affect heartbeat regularity in zebrafish, leading to bradycardia, atrioventricular blockage and ultimately death in less than 12 h [26]. Selection of this drug facilitates easy monitoring of …”