Note to users. If you're seeing this message, it means that your browser cannot find this page's style/presentation instructions -- or possibly that you are using a browser that does not support current Web standards. Find out more about why this message is appearing, and what you can do to make your experience of our site the best it can be.

Science 9 October 1964:
Vol. 146. no. 3641, pp. 266 - 268
DOI: 10.1126/science.146.3641.266
Prev | Table of Contents | Next

Articles

Eel Electroplaques: Spike Electrogenesis without Potassium Activation

Yutaka Nakamura 1, Shigehiro Nakajima 1, and Harry Grundfest 1

1 Laboratory of Neurophysiology, Department of Neurology, College of Physicians and Surgeons, Columbia University, New York 10032

Measurements with the voltage clamp technique demonstrate that only an early conductance increase occurs during spike electrogenesis of eel electroplaques. The delayed increase which is characteristic of spike electrogenesis in many other cells is absent. Instead, the membrane resistance increases two- to threefold above its resting value. The brief initial increase in conductance is due to sodium activation followed by rapid sodium inactivation. The influx of sodium causes an inward current of up to 80 ma/cm2. The inward current is abolished by eliminating the sodium from the normal medium (substitution of choline chloride for NaCl); by blocking sodium activation with tetrodotoxin; or by causing sodium inactivation through enrichment of the potassium in the medium. The delayed increase in membrane resistance is not affected by eliminating sodium influx, nor by substituting various impermeable anions for the chlorine of the normal medium. Thus, the increase in resistance signifies the occurrence of potassium inactivation which is unmasked by the absence of potassium activation.


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Tetrodotoxin: Effects on Brain Metabolism in vitro.
S. L. Chan and J. H. Quastel (1967)
Science 156, 1752-1753
   Abstract »    PDF »
Tetrodotoxin and Manganese Ion: Effects on Action Potential of the Frog Heart.
S. Hagiwara and S. Nakajima (1965)
Science 149, 1254-1255
   Abstract »    PDF »
Adaptation in Stretch Receptor Neurons of Crayfish.
S. Nakajima (1964)
Science 146, 1168-1170
   Abstract »    PDF »


To Advertise     Find Products

Science. ISSN 0036-8075 (print), 1095-9203 (online)