Journal of Neuroscience, Vol 11, 1413-1420, Copyright © 1991 by Society for Neuroscience
Dependence of Ca2+ and K+ current development on RNA and protein synthesis in muscle-lineage cells of the ascidian Boltenia villosa
L Simoncini and WJ Moody
Department of Zoology, University of Washington, Seattle 98195.
The early development of excitability of muscle-lineage cells of the
ascidian Boltenia villosa is characterized by the appearance, just after
gastrulation, of a Ca2+ current and a delayed outward K+ current, while an
inwardly rectifying K+ current, present since fertilization, disappears.
The muscle-lineage cells are the first cells in which we detect
tissue-specific electrical properties after gastrulation. Here, we show
that the development of electrical properties in these cells involves RNA
and protein synthesis. If transcription or translation is blocked, the Ca2+
and outward K+ currents fail to appear, whereas the inward K+ current
disappears normally. For the Ca2+ current, the sensitive period for
transcription extends until just before gastrulation, while the sensitive
period for translation extends until after gastrulation. The oocyte has a
Ca2+ current present at about 5- 10% the density of that in the
muscle-lineage cells; this current disappears by gastrulation. A comparison
of the oocyte and muscle Ca2+ currents indicates that they are similar in
voltage dependence and inactivation mechanism. A small difference in
permeability sequence can be attributed to different surface charge
properties at the two stages of development.