Andrew Huxley, Nobel-Winning Physiologist, Dies at 94

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Sir Andrew Huxley, a British scientist from an illustrious family whose boyhood mechanical skills led to a career in physiology -- "the mechanical engineering of living things," he called it -- and a Nobel Prize for explaining the electrical basis of bodily movement, died on Wednesday. He was 94.

His death was announced by Cambridge University's Trinity College, where he had served as master from 1984 to 1990.

Professor Huxley, a half brother of the novelist Aldous Huxley, shared the 1963 Nobel in Physiology or Medicine with his collaborator and former teacher, Sir Alan Hodgkin of Britain, and Sir John Eccles of Australia for explaining how nerve cells transmit electrical signals to control every bodily action and sensation.

Professor Huxley and Professor Hodgkin's work further explained how anesthesia works, laid the groundwork for devices that operate prosthetic limbs, and led to the identification of certain genetic diseases.

The two specifically explained how electricity travels the length of a single nerve cell, while Dr. Eccles described how the impulse jumps from one nerve cell to the next.

Their research solved a mystery dating from 1771, when the Italian physicist Luigi Galvani zapped the leg of a dead frog with electricity, making it twitch. Movement required electricity, but how did electrical current pulse through living things?

Professor Huxley and Professor Hodgkin ran experiments using a nerve cell extracted from a squid. The nerve cell, known as the giant axon, is the largest found in any species, running the entire length of the creature. The researchers threaded the long, stringy axon with an electrode and measured the changes in voltage as a current swept the nerve.

Based on their measurements, they proposed that electrically charged atoms called ions moved through hinged gates in the cell membrane to generate electricity. First sodium ions entered the axon through one gate, and then potassium ions exited through another.

Through this flux of ions, the electrical impulse propagated itself along the length of the axon, transmitting signals for action, thought, sight or touch from one end of the nerve to the other, they said.

No instrument at the time was capable of detecting the ion gates. So to test their explanation, the scientists devised a series of equations to see if the laws of physics could predict the voltage changes they had seen in their squid experiments. Most of the number crunching fell to Professor Huxley, a mathematical whiz. His results closely matched their research data, suggesting that their theory was correct.

Their insight, known as the ionic hypothesis, solved one of the leading questions in brain science at the time. The hypothesis helped explain the numbing effects of anesthetics, which block the activity of ions, and it made possible devices that harness electricity from brain cells to operate prosthetic limbs. Their research also led to the identification of genetic diseases known as channelopathies, which result from defects in ion gates, or ion channels as they are known today.

Beyond this, the ionic hypothesis gave scientists a framework for studying the cells that make up the nervous system.

"It did for the cell biology of neurons what the structure of DNA did for the rest of biology," Dr. Eric R. Kandel, a Nobel laureate, wrote in his 2006 memoir, "In Search of Memory," about his career in brain science.

In awarding the Nobel Prize to Professor Huxley and Professor Hodgkin, the Karolinska Institute in Sweden called their discovery a "milestone" toward understanding electrical stimulation of nerve cells.

Andrew Fielding Huxley was born in London on Nov. 22, 1917, the son of Leonard Huxley, a writer, and the former Rosalind Bruce.

His grandfather Thomas Huxley was a noted 19th-century biologist and early proponent of evolutionary theory. Julian Huxley, a pioneer in the field of animal behavior, and Aldous Huxley, the author of "Brave New World" and other works, were half brothers from his father's first marriage.

Professor Huxley said his famous siblings had little influence on him when he was growing up; in fact, he said, they seemed more like uncles than brothers because of the age differences: Julian was 30 and Aldous was 23 when Andrew was born. He credited his technical gifts to his mother, who encouraged woodworking and was good with her hands.

When Professor Huxley was 14, his parents gave him a lathe, which he used to build wooden candlesticks, and a working internal combustion engine. (He kept the candlesticks all his life.) He later used the lathe to build apparatuses for his experiments, including those that led to the Nobel.

His father died when he was 15. His mother, recognizing her son's mechanical talent, encouraged Professor Huxley to study physics; in 1935, he entered Cambridge University with plans to become an engineer. But he switched his focus to physiology after taking the subject to fulfill an elective.

He received his bachelor's degree in 1938 and his master's in 1945. During the summer of 1939 he joined Professor Hodgkin, who was one of his teachers, at the Marine Biological Laboratory in Plymouth, England, to begin their studies with the squid axon. But they were forced to put their work aside after World War II broke out that September with Germany's invasion of Poland.

Professor Huxley, recruited by the British Anti-Aircraft Command, worked on developing radar control of antiaircraft guns. Later he was transferred to the Admiralty, where he did the same work for naval gunnery. The wartime research sharpened his already considerable mathematical skills, preparing him for his later success in devising the equations that explained the electrical conductivity of nerves.

Professor Huxley resumed his collaboration with Professor Hodgkin in 1946, and they published their findings in 1952. Two decades later, the German physiologists Erwin Neher and Bert Sakmann obtained the first recording of the small electric currents that pass through ion gates -- a discovery that proved the existence of ion channels and earned the 1991 Nobel Prize in Physiology or Medicine.

Professor Huxley's later research explored electrical conductivity in muscles. He was a physiology professor at University College in London from 1960 to 1983, and then master of Trinity College. He was named a fellow in the Royal Society in 1955 and served as its president from 1980 to 1985. He was knighted in 1974.

His wife, the former Jocelyn Richenda Gammell Pease, died in 2003. His survivors include a son and five daughters.

nation

This article originally appeared in The New York Times.


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