458 The Molecular Basis of Nerve Conduction /24 : 5 



The effects of ACh as well as the mechanical and chemical effects 

 uncovered by the subthreshold analog may all be relatively unimportant 

 secondary manifestations of the primary- process of the conduction of 

 spike potentials. The analog experiments emphasize the important 

 role of Ca + + not used explicitly in the equations based on the voltage 

 clamped nerves. (The Ca ++ action must be there implicitly because 

 g K , J Na , g h , and V L , as well as all the a's and /3's, probably depend on the 

 concentration of calcium ions.) 



The data from voltage clamped nerves make the axon appear far 

 more complex than it did to investigators in the 1930's who were success- 

 fully applying electronic techniques to biological phenomena. The 

 molecular basis for the resting potential as well as the spike potential 

 is a challenging, unsolved problem. These are two facets of the more 

 general problem of how membranes actively transport small ions against 

 a concentration gradient. 



REFERENCES 



The following references were used in preparing this chapter : 



1. Barron, E. S. G., ed., Modern Trends in Physiology and Biochemistry (New 

 York: Academic Press, Inc., 1952). 



a. Grundfest, H., "Mechanisms and Properties of Biological Potentials," 

 pp. 193-229. 



b. Tobias, J. M., " Ultrastructure and Function in Nerve," pp. 291-322. 



c. Nachmansohn, D., "Chemical Mechanisms of Nervous Activity," 

 pp. 230-276. 



2. Grundfest, Harry, C. Y. Kao, and Mario Altamirano, "Bioelectric Effects 

 of Ions Microinjected Into the Giant Axon of Loligo," J. Gen. Physiol. 38: 

 245-282 (Nov. 20, 1954). 



3. Clamped Nerve Experiments: 



a. Hodgkin, A. L., A. F. Huxley, and B. Katz, "Measurement of 

 CurrentA T oltage Relations in Membrane of Giant Axon of Loligo," 

 J. Physiol. 116: 424-448 (Apr. 28, 1952). 



b. Hodgkin, A. L., and A. F. Huxley, "Currents Carried by Sodium and 

 Potassium Ions Through Membrane of Giant Axon of Loligo," 

 J. Physiol. 116: 449-472 (Apr. 28, 1952). 



c. Hodgkin, A. L., and A. F. Huxley, "Components of Membrane 

 Conductance in Giant Axon of Loligo," J. Physiol. 116: 473-496 

 (Apr. 28, 1952). 



d. Hodgkin, A. L., and A. F. Huxley, "Dual Effect of Membrane 

 Potential on Sodium Conductance in Giant Axon of Loligo," J. 

 Physiol. 116: 497-506 (Apr. 28, 1952). 



