External Calcium Ions are Required for Potassium Channel Gating in Squid Neurons

• Published in: Science (American Association for the Advancement of Science) 1987-05, Vol.236 (4802), p.712-714
• Main Authors: Armstrong, Clay M., Lopez-Barneo, Jose
• Format: Article
• Language: English
• Subjects: Active biological transport; Animals; Barium - pharmacology; Biological and medical sciences; Biological transport, Active; Calcium; Calcium (Chemical element); Calcium - physiology; Cations, Divalent; Cell Membrane - physiology; Chemistry; Decapodiformes; Electric Conductivity; Electric current; Electric potential; Fundamental and applied biological sciences. Psychology; giant axons; Invertebrates; Ion channels; Ion Channels - drug effects; Ion Channels - physiology; Ion currents; Ion flow dynamics; Loligo pealei; Mollusca; Nervous system; Neurons; Neurons - physiology; Physiological aspects; Physiology. Development; Potassium; Potassium (Chemical element); Potassium - metabolism; Potassium channels; Squid; Squids; Stellate Ganglion - cytology
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.2437654

The effects of calcium removal on the voltage-dependent potassium channels of isolated squid neurons were studied with whole cell patch-clamp techniques. When the calcium ion concentration was lowered from 10 to 0 millimolar (that is, no added calcium), potassium channel activity, identified from its characteristic time course, disappeared within a few seconds and there was a parallel increase in resting membrane conductance and in the holding current. The close temporal correlation of the changes in the three parameters suggests that potassium channels lose their ability to close in the absence of calcium and simultaneously lose their selectivity. If potassium channels were blocked by barium ion before calcium ion was removed, the increases in membrane conductance and holding current were delayed or prevented. Thus calcium is an essential cofactor in the gating of potassium channels in squid neurons.