Andrew Fielding Huxley (1917–2012) Biophysicist Who Showed How Nerves Carry Electrical Signals and Muscles Contract

COMMENT OBITUARY Andrew Fielding Huxley (1917–2012) Biophysicist who showed how nerves carry electrical signals and muscles contract.

ndrew Fielding Huxley made three Hodgkin and Huxley measured the observation, published in 1958, showed crucial discoveries in physiology and kinetics and voltage dependence of these how voltage differences across the surface biophysics. For establishing how ions permeability changes and expressed them membranes of muscle fibres are transmitted Acarry electrical signals in nerves, he shared as equations, which Huxley evaluated using deep within the cell along transverse tubules the Nobel prize with Alan Hodgkin and a mechanical calculator. Their formula- spaced periodically along the fibre. We now John Eccles in 1963. He also described how tion still provides the framework for our know that the signal stimulates the release molecular motors enable muscles to shorten understanding of electrical activity in the of calcium ions, which activate the contrac- and exert force and how electrical activity tion system. Hundreds of similar signal triggers the contraction of muscle fibres. cascades that result in the inward spread Huxley died on 30 May at the age of of electrical or hormonal excitation have 94. He grew up in Cambridge, UK, in a since been discovered in endocrinology, prominent academic and literary dynasty. neuroscience and immunology. To his immense pride, his grandfather, Huxley held prominent academic the anatomist Thomas Henry Huxley, positions — as head of physiology at ‘Darwin’s bulldog’, had defended Charles University College London (beginning Darwin in early debates about evolution. in 1960), president of the Royal Soc Andrew’s half-brothers were Brave New iety (1980–85), president of the British World author Aldous and evolutionary Science Association (1976–77) and COLLECTION/CORBIS HULTON-DEUTSCH biologist Julian Huxley. master of Trinity College, Cambridge Andrew Huxley obtained his under- (1984–90). His management style was graduate degree in physiology from the meticulous, and at times considered University of Cambridge, UK, in 1938. too exacting. His research was interrupted by the Many of his concerns resonate today: Second World War, during which he the funding of research and faculty in applied himself to developing radar and times of scarcity, industry–university gunnery. After the war, he did not bother partnerships, the free dissemination of with a doctorate: it is said that no one results and England’s role in interna- felt competent to serve on his awarding tional scientific programmes. Like his committee. But to his students, who knew grandfather, he spoke strongly for the him as Prof, Huxley’s formidable intellect evaluation of scientific results solely on was made less daunting by his warmth, their merits, and he opposed the sup- modesty and enthusiasm. His marriage to nervous system and throughout the body. pression of studies on the basis of their the delightful Richenda Pease resulted in It presaged the discovery of the sodium and unpopularity or for political contingencies. six children. potassium channels central to brain activity As postdoctoral fellows in Huxley’s lab Huxley first encountered the squid giant and is also the basis for our understanding oratory, we had much contact with Prof over axon in 1939, working with Hodgkin at the of the heartbeat, cardiac arrhythmias and the years, although we did not share many Laboratory of the Marine Biological Asso- many drugs. publications. He had a strict attitude towards ciation in Plymouth, UK, and resumed work Huxley turned next to muscle contraction, authorship and listed himself only if his on it after the war. This large nerve fibre reviving a boyhood interest in mechanical contribution was high, but he was always provided the keys to understanding the devices and optical microscopy. He built a interested and helpful. He had little patience electrical activity that excites biological two-beam interference microscope and used for those who were unprepared, but for those cells, which had been a mystery since the it to discover how muscle produces force and who were, his views were a gold mine. eighteenth-century experiments of Luigi shortens, and how electrical signals activate Andrew Huxley inspired generations of Galvani and Alessandro Volta in muscle contraction. scientists with his careful, imaginative tech- excitability and electricity. In 1954, with Rolf Niedergerke (who nique and his clear vision. His uses of new Huxley and Hodgkin’s collaboration also died this year), Huxley published the instrumentation and the interplay between with biophysicist Bernard Katz yielded the ‘sliding-filament’ hypothesis, which showed experimental tests and quantitative models sodium theory of the action potential. Pub- that myosin and actin protein filaments slide are ideals to be emulated. ■ lished in 1952, this work showed that the relative to one other as muscles shorten. The axon membrane can, within a millisecond, filaments are propelled by myosin molecular Yale E. Goldman and Clara Franzini- switch from being permeable to potassium motors that ‘walk’ along the actin, attaching Armstrong are at the Pennsylvania Muscle ions to being permeable to sodium ions and detaching. Huxley’s ideas underpin a Institute, and Clay M. Armstrong is instead, causing a voltage spike termed the host of molecular motors and cell-motility in the Department of Physiology, at the action potential. The inflow of sodium ions mechanisms, which are important in the Perelman School of Medicine, University of initiates and reinforces the impulse as it cardiovascular and neurological systems Pennsylvania, Philadelphia, Pennsylvania carries a signal along the axon, from a finger- and cancer. 19104, USA. tip to the spinal cord to the brain, for example. Huxley’s second pivotal microscopic e-mail: [email protected]