¹ From the Department of Physiology, School of Medicine, University of Maryland, Baltimore, Maryland 21201.

Dr. Schauf's present address is Department of Neurological Science, Rush-Presbyterian-St. Luke's Medical Center, Chicago, Illinois 60612.

All analysis of the sodium and potassium conductances of Myxicola giant axons was made in terms of the Hodgkin-Huxley m, n, and h variables. The potassium conductance is proportional to n². In the presence of conditioning hyperpolarization, the delayed current translates to the right along the time axis. When this effect was about saturated, the potassium conductance was proportional to n³. The sodium conductance was described by assuming it proportional to m³h. There is a range of potentials for which _h and h values fitted to the decay of the sodium conductance may be compared to those determined from the effects of conditioning pulses. _h values determined by the two methods do not agree. A comparison of h values determined by the two methods indicated that the inactivation of the sodium current is not governed by the Hodgkin-Huxley h variable. Computer simulations show that action potentials, threshold, and subthreshold behavior could be accounted for without reference to data on the effects of initial conditions. However, recovery phenomena (refractoriness, repetitive discharges) could be accounted for only by reference to such data. It was concluded that the sodium conductance is not governed by the product of two independent first order variables.

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This article has been cited by other articles:

				G. Baranauskas and M. Martina Sodium Currents Activate without a Hodgkin and Huxley-Type Delay in Central Mammalian Neurons J. Neurosci., January 11, 2006; 26(2): 671 - 684. [Abstract] [Full Text] [PDF]

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