ThediscoveryofionchannelsThe notion of the existence of some type of narrow ionchannel arose inthe 1920s.Thedevelopment of thethermionic values and the cathode ray oscilloscope, whichwould allow greatertime-resolutionofthe experiment aswellasgreaterreproducibilitybetweendifferentexperiments.As surprisinglyaccurate as these early results would be,the ability to measure the voltage of a cell membranedirectly wouldremainimpossiblewithoutelectrodes smallenough to insert directly inside the cell itself
The notion of the existence of some type of narrow ion channel arose in the 1920s. The development of the thermionic values and the cathode ray oscilloscope, which would allow greater time-resolution of the experiment as well as greater reproducibility between different experiments. As surprisingly accurate as these early results would be, the ability to measure the voltage of a cell membrane directly would remain impossible without electrodes small enough to insert directly inside the cell itself. The discovery of ion channels
Inthe20thcenturyIn1937,JohnZacharyYoung(1907-1997)wasoneofthefirstto make use of squid neuronsto study ionic currents.Theease of working withlarge neurons madeimportantexperimentspossibleforthefirsttime,includingthefirstintracellularrecordingsofthe nerve cell action potential,as well as the first measurements of the underlying ioniccurrents that produce them.His discovery and work withgiant squid axons eventuallyled tothe award of theNobelPrizeto Alan HodgkinandAndrew Huxley.The appearanceof true cellular electrophysiology followedtheintroduction,in 1949,of intracellular glassmicroelectrodes byGilbertLingandRalf Gerard.Withthisinvention,it became possible to detect and measuretherestingpotential of acell by impalingits membrane,withoutdestroyingthecell
In the 20th century In 1937, John Zachary Young (1907–1997) was one of the first to make use of squid neurons to study ionic currents. The ease of working with large neurons made important experiments possible for the first time, including the first intracellular recordings of the nerve cell action potential, as well as the first measurements of the underlying ionic currents that produce them. His discovery and work with giant squid axons eventually led to the award of the Nobel Prize to Alan Hodgkin and Andrew Huxley. The appearance of true cellular electrophysiology followed the introduction, in 1949, of intracellular glass microelectrodes by Gilbert Ling and Ralf Gerard. With this invention, it became possible to detect and measure the resting potential of a cell by impaling its membrane, without destroying the cell
Inthe20thcenturyUsingsquidneurons,AlanLloydHodgkinandBernardKatz(1949)removedsodiumionsfromoutsidetheneuronandwere able to concludefromtheir data thatsodiumionswereresponsiblefortheformation of theaction potential.The next improvement in instrumentationtookplacearound the same period when Kenneth Cole and GeorgeMarmontdescribedthe concept of the voltageclampmethod.Thisapproachconsistedofplacingasecondglass electrode inside the cell in orderto stabilize or“"clamp"themembranepotentialofneuronsforexperimentalpurposes.Voltageclampingallowedmeasurementsoftheeffectofchangesinmembranepotentialonthe conductanceofthismembranetovariousindividualionspecies
In the 20th century Using squid neurons, Alan Lloyd Hodgkin and Bernard Katz (1949) removed sodium ions from outside the neuron and were able to conclude from their data that sodium ions were responsible for the formation of the action potential. The next improvement in instrumentation took place around the same period when Kenneth Cole and George Marmont described the concept of the voltage clamp method. This approach consisted of placing a second glass electrode inside the cell in order to stabilize or “clamp” the membrane potential of neurons for experimental purposes. Voltage clamping allowed measurements of the effect of changes in membrane potential on the conductance of this membrane to various individual ion species
Hodgkinand HuxleyIntheearly1950s,twoBritishscientistsAlanHodgkinandAndrew Huxley characterized the time and voltagedependencyof the ionicconductancesthat underlieanaction potential in the squid giant axon,using the voltageclamptechnique,anddevelopeda mathematical modelthat accurately predicted the waveform of theactionpotential.This was a major breakthrough.For this determining workon neuronal excitability,Hodgkinand Huxley receivedtheNobelPrize inPhysiologyorMedicine in 1963.Theyshowed howiontransportthrough nervecell membranesproduces a signal thatis conveyedfrom nerve cell to nervecell likearelayracebaton.Itisprimarilysodiumandpotassium ions, Nat and Kt, that are active in thesereactions
Hodgkin and Huxley In the early 1950s, two British scientists Alan Hodgkin and Andrew Huxley characterized the time and voltage dependency of the ionic conductances that underlie an action potential in the squid giant axon, using the voltage clamp technique, and developed a mathematical model that accurately predicted the waveform of the action potential. This was a major breakthrough. For this determining work on neuronal excitability, Hodgkin and Huxley received the Nobel Prize in Physiology or Medicine in 1963. They showed how ion transport through nerve cell membranes produces a signal that is conveyed from nerve cell to nerve cell like a relay race baton. It is primarily sodium and potassium ions, Na+ and K +, that are active in these reactions
Nobel Prize-lon channels1963lonicmechanismsofnervecellmembraneEccles,JohnCarew1/27/1903to5/2/1997AustralianHodgkin,AlanLloyd2/5/1914to12/20/1998BritishHuxley,SirAndrewFielding12/22/1917toBritish
Nobel Prize – Ion channels 1963 Ionic mechanisms of nerve cell membrane Eccles, John Carew 1/27/1903 to 5/2/1997 Australian Hodgkin, Alan Lloyd 2/5/1914 to 12/20/1998 British Huxley, Sir Andrew Fielding 12/22/1917 to British