Kress Michaela and Reeh Peter W.
- Published in print:
- 1996
- Published Online:
- March 2012
- ISBN:
- 9780198523345
- eISBN:
- 9780191724527
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198523345.003.0011
- Subject:
- Neuroscience, Sensory and Motor Systems
From early psychophysical studies a variety of exogenous and endogenous substances have been found to induce pain and hyperalgesia, that is, to be algogenic. To study the underlying mechanisms ...
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From early psychophysical studies a variety of exogenous and endogenous substances have been found to induce pain and hyperalgesia, that is, to be algogenic. To study the underlying mechanisms several behavioural and reflex models have been developed in animals. However, it has been difficult to differentiate between peripheral and central mechanisms. Single-fibre recordings provided a tool for isolating the contributions of primary afferents. Controlled application of defined mediator concentrations became feasible allowing for the investigation of the direct effects on nociceptive nerve endings. These sensory terminals, however, comprise receptive membrane sections, action potential generator region(s), and conductive zones of the axon, each of which could be the target of a chemical mediator. To differentiate these would require intracellular recording of the membrane potential or currents; this is not achievable due to the submicroscopic size of nociceptive nerve endings and their embedding in the tissue. Considering the cell soma in dissociated sensory ganglion cultures to be a model of its receptive ending, valuable information can be obtained from patch-clamp recordings of chemically mediated membrane effects.Less
From early psychophysical studies a variety of exogenous and endogenous substances have been found to induce pain and hyperalgesia, that is, to be algogenic. To study the underlying mechanisms several behavioural and reflex models have been developed in animals. However, it has been difficult to differentiate between peripheral and central mechanisms. Single-fibre recordings provided a tool for isolating the contributions of primary afferents. Controlled application of defined mediator concentrations became feasible allowing for the investigation of the direct effects on nociceptive nerve endings. These sensory terminals, however, comprise receptive membrane sections, action potential generator region(s), and conductive zones of the axon, each of which could be the target of a chemical mediator. To differentiate these would require intracellular recording of the membrane potential or currents; this is not achievable due to the submicroscopic size of nociceptive nerve endings and their embedding in the tissue. Considering the cell soma in dissociated sensory ganglion cultures to be a model of its receptive ending, valuable information can be obtained from patch-clamp recordings of chemically mediated membrane effects.
Alan J. McComas
- Published in print:
- 2011
- Published Online:
- September 2011
- ISBN:
- 9780199751754
- eISBN:
- 9780199897094
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199751754.003.0009
- Subject:
- Neuroscience, History of Neuroscience, Sensory and Motor Systems
At Cambridge, Elliott, and then Langley, speculate that impulses liberate chemicals from nerve endings. Others, including Adrian, believe that nerve endings exert their effects by electric currents ...
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At Cambridge, Elliott, and then Langley, speculate that impulses liberate chemicals from nerve endings. Others, including Adrian, believe that nerve endings exert their effects by electric currents flowing through the synapses. In Austria, Otto Loewi dreams of a way to detect any chemical released by the endings of the vagus nerve in the frog heart. The method works and the chemical is later identified as acetylcholine—the first neurotransmitter to be discovered. In London, Henry Dale’s pharmacological experiments lead him to suggest that acetylcholine is also the transmitter in the sympathetic ganglia and at the nerve endings on muscle fibres. His later experiments are aided by Wilhelm Feldberg’s sensitive bioassay for acetylcholine. John Eccles, however, is still convinced that electric currents are responsible for part, or all, of the excitatory and inhibitory effects at synapses. Dale and Loewi share the 1936 Nobel Prize.Less
At Cambridge, Elliott, and then Langley, speculate that impulses liberate chemicals from nerve endings. Others, including Adrian, believe that nerve endings exert their effects by electric currents flowing through the synapses. In Austria, Otto Loewi dreams of a way to detect any chemical released by the endings of the vagus nerve in the frog heart. The method works and the chemical is later identified as acetylcholine—the first neurotransmitter to be discovered. In London, Henry Dale’s pharmacological experiments lead him to suggest that acetylcholine is also the transmitter in the sympathetic ganglia and at the nerve endings on muscle fibres. His later experiments are aided by Wilhelm Feldberg’s sensitive bioassay for acetylcholine. John Eccles, however, is still convinced that electric currents are responsible for part, or all, of the excitatory and inhibitory effects at synapses. Dale and Loewi share the 1936 Nobel Prize.
