Biophysical Journal 27: 193-208 (1979)
© 1979 the Biophysical Society

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Schauf, C L Articles by Bullock, J O Search for Related Content PubMed PubMed Citation Articles by Schauf, C L Articles by Bullock, J O

Modifications of sodium channel gating in Myxicola giant axons by deuterium oxide, temperature, and internal cations.

ABSTRACT

In dialyzed Myxicola axons substitution of heavy water (D2O) externally and internally slows both sodium and potassium kinetics and decreases the maximum conductances. Furthermore, this effect is strongly temperature dependent, the magnitude of the slowing produced by D2O substitution decreasing with increasing temperature over the range 3-14 degrees C with a Q10 of approximately 0.71. The relatively small magnitude of the D2O effect, combined with its strong temperature dependence, suggests that the rate limiting process producing a conducting channel involves appreciable local changes in solvent structure. Maximum conductances in the presence of D2O were decreased by approximately 30%, while the voltage dependences of both gNa and gK were not appreciably changed. In contrast to the effects of heavy water substitution on the ionic currents, membrane asymmetry currents were not altered by D2O, suggesting that gating charge movement may preceed by several steps the final transformation of the Na+ channel to a conducting state. In Myxicola axons the effect of temperature alone on asymmetry current kinetics can be well described via a simple temporal expansion equivalent to a Q10 of 2.2, which is somewhat less than the Q10 of GNa activation. The integral of membrane asymmetry current, representing maximum charge movement, is however not appreciably altered by temperature.

This article has been cited by other articles:

				M. Ikeda, S. Suzuki, M. Kishio, M. Hirono, T. Sugiyama, J. Matsuura, T. Suzuki, T. Sota, C. N. Allen, S. Konishi, et al. Hydrogen-Deuterium Exchange Effects on {beta}-Endorphin Release from AtT20 Murine Pituitary Tumor Cells Biophys. J., January 1, 2004; 86(1): 565 - 575. [Abstract] [Full Text] [PDF]