Prof. Sir Andrew Huxley, widely regarded as one of Britain's most eminent scientists and great university administrators, the former master of Trinity College, Cambridge, shared the Nobel Prize in Physiology or Medicine in 1963 with Sir Alan Hodgkin, a lifelong friend and collaborator, and with Australian scientist Sir John Eccles, who was cited for research on synapses. They received the prize for unravelling the biophysical mechanism of nerve impulses which control muscle action.

Huxley and Hodgkin began collaborating on the nature of nerve impulses in August 1939, when Hodgkin invited him down to the Plymouth Marine Laboratory, following his return from America. While there, he had successfully demonstrated the mechanism by which electrical impulses activate the next segment of a nerve fibre, and had begun to work with the recently discovered nerve fibre of the giant squid. At the time, there was controversy about the way in which neural signals were generated and transmitted along fibres and across synapses the connecting junctions where there are gaps between the ends of one fibre and the beginning of the next.

The scientists began experiments on the very large nerve fibres (diameter about 0.5mm) possessed by squids. Their first task was to measure the viscosity of the interior of the fibre by suspending it vertically and dropping droplets of mercury down it. This failed because the mercury droplets stopped as they entered the fibre, showing that its interior was a solid, not a viscous liquid as supposed. Instead, they pushed an electrode down inside, in order to measure directly the potential difference between inside and outside and obtained a direct recording of the voltages across the nerve membrane, the first time that this had been done.

The consensus of the time was that the interior of a fibre at rest was up to one-tenth of a volt negative relative to the external solution, but rose to equality with the external potential at the peak of a nerve impulse. The pair confirmed this as regards the resting state, but the internal potential at the peak of the impulse was substantially positive. They published a short paper in the journal Nature, announcing their achievement of recording action potentials from inside a nerve fibre.

However, their work was suspended with the outbreak of the Second World War, during which time Huxley was involved in a number of projects. Initially a clinical student in London, due to the Blitz teaching was suspended, and Huxley spent the rest of the war on operational research in gunnery, first for Anti-Aircraft Command and later for the Admiralty, working in a team under Patrick (later Lord) Blackett. Hodgkin worked in radar research with the Air Ministry.

In spite of the war and their involvement in widely separated and often secret activities, the two men remained in touch and even swapped advice on particular problems. One such occasion saw Huxley design and produce, using a lathe, a new type of gun sight during the development of airborne radar.

Soon after the war, in 1946, they returned to neurological research at Cambridge. Their work necessitated the development of specialist equipment which in many cases was not only designed by Huxley, but also built by him. They began discussing how the squid membrane becomes specifically permeable to sodium ions. These are about ten times more concentrated in the external solution than inside the fibre, so they diffuse inwards, carrying their positive charge.

Within six years, Huxley and Hodgkin had laid the detailed foundations of the modern understanding of the transmission of nerve impulses. Their model, which was developed well before the advent of electron microscopes or computer simulations, was able to give scientists a basic understanding of how nerve cells work without having a detailed understanding of how the membrane of a nerve cell looked.

They demonstrated that these travel, not along the core of the fibre, but along the outer membrane as a product of successive cascades of two types of ion. The finding and the detailed mathematical theory that accompanied the work, completed in 1952 in a series of five papers, was groundbreaking and resulted in their share of the Nobel Prize.

Born in Hampstead in 1917, Andrew Fielding Huxley came from a celebrated family. His grandfather was Thomas Huxley, the 19th century biologist and staunch supporter of Charles Darwin; his two half-brothers were Julian Huxley, also a biologist, and Aldous Huxley, author of the novel Brave New World.

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Sir Andrew Huxley: Eminent scientist whose pioneering work earned him a Nobel Prize in 1963