We began with a paper by Alan Hodgkin and Bernard Katz (“The Effect of Sodium Ions on the Electrical Activity of the Giant Axon of the Squid,” Journal of Physiology, Volume 108, Pages 37–77, 1949) that tests the hypothesis that the nerve membrane becomes selectively permeable to sodium during an action potential. We then moved on to Alan Hodgkin and Andrew Huxley’s monumental 1952 paper in which they present the Hodgkin-Husley model of the squid nerve axon (“A Quantitative Description of Membrane Current and Its Application to Conduction and Excitation in Nerve,” Journal of Physiology, Volume 117, Pages 500–544, 1952). In order to provide a more modern view of the ion channels that underlie Hodgkin and Huxley’s model, we next read an article by Roderick MacKinnon and his group (“The Structure of the Potassium Channel: Molecular Basis of K+ Conduction and Selectivity,” Science, Volume 280, Pages 69–77, 1998). Then we read a paper by Erwin Neher, Bert Sakmann and their colleagues that described patch clamp recordings of single ion channels (“Improved Patch-Clamp Techniques for High-Resolution Current Recordings from Cells and Cell-Free Membrane Patches,” Pflugers Archive, Volume 391, Pages 85–100, 1981).
This week I wanted to cover one-dimensional cable theory, so I chose one of my favorite papers, by Alan Hodgkin and William Rushton (“The Electrical Constants of a Crustacean Nerve Fibre,” Proceedings of the Royal Society of London, B, Volume 133, Pages 444–479, 1946). I recall reading this lovely article during my first summer as a graduate student at Vanderbilt University (where my daughter Kathy is now an attending college). My mentor, John Wikswo, had notebook after notebook full of research papers about nerve electrophysiology, and I set out to read them all. Learning a subject by reading the original literature is an interesting experience. It is less efficient than learning from a textbook, but you pick up many insights that are lost when the research is presented in a condensed form. Hodgkin and Rushton’s paper contains the fascinating quote
Electrical measurements were made by applying rectangular pulses of current and recording the potential response photographically. About fifteen sets of film were obtained in May and June 1939, and a preliminary analysis was started during the following months. The work was then abandoned and the records and notes stored for six years [my italics]. A final analysis was made in 1945 and forms the basis of this paper.During those six years, the authors were preoccupied with a little issue called World War II.
Sometimes I like to provide my students with biographical information about the authors of these papers, and I had already talked about my hero, the Nobel Prize-winning Alan Hodgkin, earlier in the semester. So, I did some research on Rushton, who I was less familiar with. It turns out, he is known primarily for his work on vision. William Albert Hugh Rushton (1901–1980) has only a short Wikipedia entry, which does not even discuss his work on nerves. (Footnote: Several months ago, after reading—or rather listening to while walking my dog Suki—The Wikipedia Revolution: How a Bunch of Nobodies Created the World’s Greatest Encyclopedia by Andrew Lih, I became intensely interested in Wikipedia and started updating articles related to my areas of expertise. This obsession lasted for only about a week or two. I rarely make edits anymore, but I may update Rushton’s entry.) Rushton was a professor of physiology at Trinity College in Cambridge University. He became a Fellow of the Royal Society in 1948, and received the Royal Medal from that society in 1970.
Horace Barlow wrote an obituary for Rushton in the Biographical Memoirs of Fellows of the Royal Society (Volume 32, Pages 423–459, 1986). It begins
William Rushton first achieved scientific recognition for his work on the excitability of peripheral nerve where he filled the gap in the Cambridge succession between Lord Adrian, whose last paper on peripheral nerve appeared in 1922, and Alan Hodgkin, whose first paper was published in 1937. It was on the strength of this work that he was elected as a fellow of the Royal Society in 1948, but then Rushton started his second scientific career, in vision, and for the next 30 years he was dominant in a field that was advancing exceptionally fast. In whatever he was engaged he cut a striking and influential figure, for he was always interested in a new idea and had the knack of finding the critical argument or experiment to test it. He was argumentative, and often an enormously successful showman, but he also exerted much influence from the style of his private discussions and arguments. He valued the human intellect and its skillful use above everything else, and he successfully transmitted this enthusiasm to a large number of students and disciples.Another of my favorite papers by Rushton is “A Theory of the Effects of Fibre Size in Medullated Nerve” (Journal of Physiology, Volume 115, Pages 101–122, 1951). Here, he correctly predicts many of the properties of myelinated nerve axons, such as the ratio of the inner and outer diameters of the myelin, from first principles.
Both of the Rushton papers I have cited here are also referenced in the 4th edition of Intermediate Physics for Medicine and Biology. Problem 34 in Chapter 6 is based on the Hodgkin-Rushton paper. It examines their analytical solution to the one-dimensional cable equation, which involves error functions. Was it Hodgkin or Rushton who was responsible for this elegant piece of mathematics gracing the Journal of Physiology? I can’t say for sure, but in Hodgkin’s Nobel Prize autobiography he claims he learned about cable theory from Rushton (who was 13 years older than him).
William Rushton provides yet another example of how a scientist with a firm grasp of basic physics can make fundamental contributions to biology.
No comments:
Post a Comment