Hodgkin was born inBanbury, Oxfordshire, on 5 February 1914. He was the oldest of three sons ofQuakers George Hodgkin and Mary Wilson Hodgkin. His father was the son ofThomas Hodgkin and had read for theNatural Science Tripos atCambridge where he had befriended electrophysiologistKeith Lucas.[1]
Because of poor eyesight, he was unable to study medicine and eventually ended up working for a bank in Banbury. As members of theSociety of Friends, George and Mary opposed theMilitary Service Act of 1916, which introduced conscription, and had to endure a great deal of abuse from their local community, including an attempt to throw George in one of the town canals.[2] In 1916, George Hodgkin travelled to Armenia as part of an investigation of distress. Moved by the misery and suffering ofArmenian refugees he attempted to go back there in 1918 on a route through the Persian Gulf (as the northern route was closed because of theOctober Revolution in Russia). He died of dysentery inBaghdad on 24 June 1918, just a few weeks after his youngest son, Keith, had been born.[3]
Between school and college, he spent May 1932 at theFreshwater Biological Station atWray Castle based on a recommendation of his future Director of Studies atTrinity,Carl Pantin.[10] After Wray Castle, he spent two months with a German family inFrankfurt as "in those days it was thought highly desirable that anyone intending to read science should have a reasonable knowledge of German."[11] After his return to England in early August 1932, his mother Mary was remarried to Lionel Smith (1880–1972),[12] the eldest son ofA. L. Smith, whose daughter Dorothy was also married to Alan's uncleRobert Howard Hodgkin.[13]
During his studies, Hodgkin, who described himself as "having been brought up as a supporter of the British Labour Party"[19] was friends with communists[20] and actively participated in the distribution of anti-war pamphlets.[21] At Cambridge, he knewJames Klugmann[22] andJohn Cornford,[23] but he emphasised in his autobiography that none of his friends "made any serious effort to convert me [toCommunism], either then or later."[24] From 1935 to 1937, Hodgkin was a member of theCambridge Apostles.[25]
Trinity College at theUniversity of Cambridge where Hodgkin was a student from 1932 to 1935, worked as a research fellow from 1936 on and finally served asMaster from 1978 to 1984
Hodgkin started conducting experiments on how electrical activity is transmitted in thesciatic nerve of frogs in July 1934.[26] He found that anerve impulse arriving at a cold or compression block, can decrease the electrical threshold beyond the block, suggesting that the impulse produces a spread of anelectrotonic potential in the nerve beyond the block.[27] In 1936, Hodgkin was invited byHerbert Gasser, then director of theRockefeller Institute in New York City, to work in his laboratory during 1937–38. There he metRafael Lorente de Nó[28] andKenneth Stewart Cole with whom he ended up publishing a paper.[29] During that year he also spent time at theWoods Hole Marine Biological Laboratory where he was introduced to thesquid giant axon,[30] which ended up being the model system with which he conducted most of the research that eventually led to his Nobel Prize. In the spring of 1938, he visitedJoseph Erlanger atWashington University in St. Louis who told him he would take Hodgkin's local circuit theory of nerve impulse propagation seriously if he could show that altering the resistance of the fluid outside a nerve fibre made a difference to the velocity of nerve impulse conduction.[31] Working with single nerve fibres fromshore crabs andsquids, he showed that the conduction rate was much faster in seawater than in oil, providing strong evidence for the local circuit theory.[32]
After his return to Cambridge he started collaborating withAndrew Huxley who had enteredTrinity as a freshman in 1935, three years after Hodgkin.[33] With a £300 equipment grant from theRockefeller Foundation, Hodgkin managed to set up a similar physiology setup to the one he had worked with at the Rockefeller Institute. He moved all his equipment to thePlymouth Marine Laboratory in July 1939.[34] There, he and Huxley managed to insert a finecannula into the giant axon of squids and recordaction potentials from inside the nerve fibre. They sent a short note of their success to Nature just before the outbreak ofWorld War II.[35]
Despite hisQuaker upbringing, Hodgkin was eager to join the war effort as contact with the Nazis during his stay in Germany in 1932 had removed all hispacifist beliefs. His first post was at theRoyal Aircraft Establishment where he worked on issues in aviation medicine, such as oxygen supply for pilots at high altitudes and thedecompression sickness caused by nitrogen bubbles coming out of the blood.[36] In February 1940 he transferred to theTelecommunications Research Establishment (TRE) where he worked on the development of centimetricradar, including the design of thevillage Inn AGLT airborne gun-laying system. He was a member ofE.G. Bowen's group inSt Athan in South Wales and lived in a local guest house together with John Pringle andRobert Hanbury Brown. The group moved toSwanage in May 1940 where Pringle replaced Bowen as leader of the group.[37] In March 1941, Hodgkin flew on the test flight of aBristol Blenheim fitted with the first airborne centimetric radar system. In February and March 1944, he visited theMIT Radiation Laboratory to help foster the interchange of information on developments in radar between Britain and America.[38]
Providing a readable account of the little-known piece of military history that he was a part of during World War II was a main motivation for Hodgkin to write his autobiographyChance and Design: Reminiscences of Science in Peace and War.[39]
1945–1963: Action potential theory and Nobel Prize
Basic components of Hodgkin–Huxley-type models. Hodgkin–Huxley type models represent the biophysical characteristics of cell membranes. The lipid bilayer is represented as a capacitance (Cm). Voltage-gated and leak ion channels are represented by nonlinear (gn) and linear (gL) conductances, respectively. The electrochemical gradients driving the flow of ions are represented by batteries (E), and ion pumps and exchangers are represented by current sources (Ip).
As theAllied Forces'invasion of France and their continuedadvance towards Germany in autumn 1944 suggested an end of the war in the foreseeable future, Hodgkin started to plan his return to a career in research at Cambridge. He renewed his collaboration withW. A. H. Rushton and they published an article on how to calculate a nerve fibre's membrane resistance, membrane capacity, its axoplasm's resistance, and the resistance of the external fluid in which the fibre is placed, from experimental observations.[40]
After being released from military service in August 1945 uponAdrian's request, Hodgkin was able to restart his experiments in collaboration withBernard Katz and his pre-war collaboratorAndrew Huxley. They spent the summers of 1947, 1948, and 1949 at thePlymouth Marine Laboratory where they continued to measure resting and action potentials from inside the giant axon of the squid.[41] Together with Katz, he provided evidence that the permeability of the neuronal cell membrane for sodium increased during an action potential, thus allowing sodium ions to diffuse inward.[42] The data they had obtained in 1949 resulted in a series of five papers published inThe Journal of Physiology that described what became later known as theHodgkin–Huxley model of theaction potential and eventually earned Hodgkin and Huxley theNobel Prize in Physiology or Medicine.[43][44][45][46][47] Building on work byKenneth S. Cole[48] they used a technique ofelectrophysiology, known as thevoltage clamp to measure ionic currents through the membranes of squid axons while holding the membrane voltage at a set level. They proposed that the characteristic shape of theaction potential is caused by changes in the selective permeability of the membrane for different ions, specificallysodium,potassium, andchloride. Amodel that relies on a set ofdifferential equations and describes each component of an excitable cell as an electrical element was in good agreement with their empirical measurements.[47][49]
The cell membrane depolarisation sequence where a small depolarization leads to an increase in sodium permeability, which leads to influx of sodium ions, which in turn depolarizes the membrane even more[50] is now known as theHodgkin cycle.[51]
In addition, Hodgkin and Huxley's findings led them to hypothesize the existence ofion channels on cell membranes, which were confirmed only decades later. Confirmation of ion channels came with the development of thepatch clamp leading to a Nobel prize in 1991 forErwin Neher andBert Sakmann, and in 2003 forRoderick MacKinnon.[52]
After establishing ion movements across a selectively permeable cell membrane as the mechanism of the action potential, Hodgkin turned his attention to how the ionic interchange that occurs during the action potential could be reversed afterwards. Together withRichard Keynes he demonstrated that in addition to the changes in permeability that lead to an action potential, there is a secretory mechanism that ejects sodium and absorbs potassium against the electrochemical gradients.[53] A few years later, the Danish scientistJens Christian Skou discovered the enzymeNa+/K+-ATPase that usesATP to export three sodium ions in exchange for two potassium ions that are imported,[54] for which he received theNobel Prize in Chemistry in 1997.[55]
Hodgkin was nominated for the Nobel Prize in Physiology or Medicine in 1953 byLord Adrian.[56] In October 1961, he was told by Swedish journalists that he,Huxley, andEccles had been awarded the Nobel Prize. This turned out to be a false alarm, however, when shortly thereafter it was announced that the 1961 Prize was awarded toGeorg von Békésy. It was only two years later that Hodgkin,Huxley, andEccles were finally awarded the Prize "for their discoveries concerning the ionic mechanisms involved in excitation and inhibition in the peripheral and central portions of the nerve cell membrane".[57][58] During theNobel Banquet on 10 December 1963, Hodgkin gave the traditional speech on behalf of the three neurophysiologists, thanking theking and theNobel Committee for Physiology or Medicine for the award.[59] Incidentally, Hodgkin and his wife attended the Nobel Prize ceremony a second time, three years later, when Hodgkin's father-in-law,Francis Peyton Rous, was awarded the 1966 Nobel Prize in Physiology or Medicine.[60]
From 1951 to 1969, Hodgkin was the Foulerton Professor of theRoyal Society at Cambridge. In 1970 he became the John Humphrey Plummer Professor of Biophysics at Cambridge. Around this time he also ended his experiments on nerve at the Plymouth Marine Laboratory and switched his focus to visual research which he could do in Cambridge with the help of others while serving aspresident of the Royal Society. Together withDenis Baylor and Peter Detwiler he published a series of papers on turtlephotoreceptors.[61][62][63][64][65][66][67]
From 1970 to 1975 Hodgkin served as the 53rd president of the Royal Society (PRS). During his tenure as PRS, he was knighted in 1972 and admitted into theOrder of Merit in 1973.[68] From 1978 to 1985 he was the 34thMaster of Trinity College, Cambridge.[69]
He served on the Royal Society Council from 1958 to 1960 and on theMedical Research Council from 1959 to 1963. He was foreign secretary ofthe Physiological Society from 1961 to 1967. He also held additional administrative posts such as Chancellor,University of Leicester, from 1971 to 1984
During his stay at the Rockefeller Institute in 1937, Hodgkin got to know the American pathologist Francis Peyton Rous[77] who was later awarded the 1966 Nobel Prize in Physiology or Medicine.[78] When Rous invited him for dinner to his home, Hodgkin got to know Rous' daughter,Marni, who was then a student atSwarthmore College.[77] He proposed to her before going back to England in 1938, but she rejected him.[79] When Hodgkin briefly returned to the US in 1944 (seeWartime activities), they reunited and got married on 31 March.[80]
Their first daughter, Sarah, was born in April 1945, shortly before the Hodgkins moved back to Cambridge.[81] They had three more children: Deborah Hodgkin (born 2 May 1947),[82] Jonathan Hodgkin (born 24 August 1949),[83] and Rachel Hodgkin (born June 1951).[84]Marni became a Children's Book Editor atMacmillan Publishing Company and a successful writer of children's literature, includingYoung Winter's Tales andDead Indeed.Jonathan Hodgkin became a molecular biologist at Cambridge University. Deborah Hodgkin is also a successful psychologist.
Hodgkin suffered from a series of medical problems that began soon after his retirement as Master of Trinity. In 1989 he had surgery to relieve pressure on thespinal cord from one of theintervertebral discs in his neck, which left him unable to walk without support, and with progressive disablement.[73] Hodgkin died in 1998 inCambridge.[86]
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