Optical monitoring of spontaneous electrical activity of 8-somite embryonic chick heart

A HIROTA, S FUJII, K KAMINO - The Japanese journal of physiology, 1979 - jstage.jst.go.jp
A HIROTA, S FUJII, K KAMINO
The Japanese journal of physiology, 1979jstage.jst.go.jp
Using an optical method for measuring membrane potential, we monitored spontaneous
action potential activity in the embryonic chick heart at the very early developmental stages,
and found that spontaneous electrical activity was present at the developmental stage of 8
somites before the initiation of the heartbeat. Developmental changes in the electrical
activity of embryonic heart cells have received considerable attention in relation to cardiac
morphogenesis. However, in the very early stages of the embryonic heart cells the use of …
Summary
Using an optical method for measuring membrane potential, we monitored spontaneous action potential activity in the embryonic chick heart at the very early developmental stages, and found that spontaneous electrical activity was present at the developmental stage of 8 somites before the initiation of the heartbeat.
Developmental changes in the electrical activity of embryonic heart cells have received considerable attention in relation to cardiac morphogenesis. However, in the very early stages of the embryonic heart cells the use of microelectrodes to follow the membrane potential is either impossible or inconvenient because the cells are so small and frail and topological localization is complex. Thus, electrophysiological studies have been limited to embryos at later developmental stages or to cultured embryonic cells (SPERELAKIS, 1972; IRISAWA, 1978). Quite recently, optical methods of monitoring membrane potential have been introduced for systems where microelectrodes could not be used for reasons of scale, topology, or complexity (COHEN and SALZBERG, 1978). This technique is based on the observation that change in potential across membrane stained with certain dyes is accompanied by changes in their optical properties, including absorption or fluorescence (COHEN et al., 1974, 1977; Ross et al., 1977). Of the dyes that exhibit an absorption response to membrane potential, a merocyanine-oxazolone dye is one of the most sensitive and has little pharmacological or photodynamic effects on the membrane: its signal is detectable with a signalto-noise ratio greater than 10: 1 (GRINVALD et al., 1976). The efficacy of this dye has been demonstrated in simultaneous detection of neuron activity of numerous cells in the supraesophageal ganglion of barnacle (GRINVALD et al., 1976; SALZBERG et al., 1977). In our experiments, we applied optical methods to monitor the spontaneous electrical activity of the very early embryonic chick heart cells stained with
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