Co-ordinated modulation of Ca2+ and K+ currents during ascidian muscle development

The Journal of Physiology
A A GreavesW J Moody

Abstract

1. The development of Ca2+ and K+ currents was studied in ascidian muscle cells at twelve embryonic stages from gastrulation to the mature cell, a period of 24 h. A high degree of co-ordination occurs between the development of the inwardly rectifying K+ current (IK(IR)), which sets the resting potential, and Ca2+ and outward K+ currents, which determine action potential waveform. 2. At neurulation IK(IR), which had been present since fertilization, begins to decrease, reaching 12% of its previous density in 6 h. IK(IR) then immediately begins to increase again, reaching its previous density in another 6 h. 3. When IK(IR) begins to decrease, a high-threshold inactivating Ca2+ current and a slowly activating voltage-gated K+ current appear. 4. When IK(IR) returns to its previous density, two new currents appear: a sustained Ca2+ current with the same voltage dependence, but different conotoxin sensitivity than the inactivating Ca2+ current; and a Ca(2+)-dependent K+ current, which activates 8-10 times faster and at potentials 20-30 mV more negative than the voltage-dependent K+ current. 5. The transient downregulation of IK(IR) destabilizes the resting potential and causes spontaneous action potentials to occur. Because IK(IR) i...Continue Reading

Citations

Aug 26, 1998·The Journal of Physiology·A B Ribera
Jul 25, 2000·Mechanisms of Development·O CrocianiA Arcangeli
Sep 2, 2006·The Journal of Physiology·Annette K McCabeWilliam J Moody
Aug 7, 2004·The Journal of Physiology·Rebekah CorlewWilliam J Moody
Oct 20, 1998·Journal of Neurobiology·W J Moody
Mar 4, 2003·Journal of Neurophysiology·Heidi L Picken Bahrey, William J Moody
Jun 14, 2015·International Journal of Developmental Neuroscience : the Official Journal of the International Society for Developmental Neuroscience·Salvador GaliciaAmira Flores
Feb 27, 2020·Cellular and Molecular Neurobiology·Bo JinXiaofeng Yin
Apr 30, 1998·Physiological Reviews·B M Millman

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