Measurement of strains experienced by viscerofugal nerve cell bodies during mechanosensitive firing using Digital Image Correlation

Gwen Palmer, Timothy Hibberd, Tiina Roose, Simon Brookes, Mark Taylor

    Research output: Contribution to journalArticlepeer-review

    4 Citations (Scopus)

    Abstract

    Mechanosensory neurons detect physical events in the local environments of the tissues that they innervate. Studies of mechanosensitivity of neurons or nerve endings in the gut have related their firing to strain, wall tension, or pressure. Digital image correlation (DIC) is a technique from materials engineering that can be adapted to measure the local physical environments of afferent neurons at high resolution. Flat-sheet preparations of guinea pig distal colon were set up with arrays of tissue markers in vitro. Firing of single viscerofugal neurons was identified in extracellular colonic nerve recordings. The locations of viscerofugal nerve cell bodies were inferred by mapping firing responses to focal application of the nicotinic receptor agonist 1,1- dimethyl-4-phenylpiperazinium iodide. Mechanosensory firing was recorded during load-evoked uniaxial or biaxial distensions. Distension caused movement of surface markers which was captured by video imaging. DIC tracked the markers, interpolating the mechanical state of the gut at the location of the viscerofugal nerve cell body. This technique revealed heterogeneous load-evoked strain within preparations. Local strains at viscerofugal nerve cell bodies were usually smaller than global strain measurements and correlated more closely with mechanosensitive firing. Both circumferential and longitudinal strain activated viscerofugal neurons. Simultaneous loading in circumferential and longitudinal axes caused the highest levels of viscerofugal neuron firing. Multiaxial strains, reflecting tissue shearing and changing area, linearly correlated with mechanosensory firing of viscerofugal neurons. Viscerofugal neurons were mechanically sensitive to both local circumferential and local longitudinal gut strain, and appear to lack directionality in their stretch sensitivity.

    Original languageEnglish
    Pages (from-to)G869-G879
    Number of pages10
    JournalAmerican Journal of Physiology-Gastrointestinal and Liver Physiology
    Volume311
    Issue number5
    DOIs
    Publication statusPublished - 2016

    Keywords

    • Afferent
    • Biomechanics
    • Digital image correlation
    • Mechanosensory
    • Strain
    • Viscerofugal

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