Mechanical properties of axons.
The mechanical response of PC12 neurites under tension is investigated using a microneedle technique. Elastic response, viscoelastic relaxation, and active contraction are observed. The mechanical model proposed by Dennerll et al. [J. Cell Biol. 109, 3073 (1989).10.1083/jcb.109.6.3073], which involves three mechanical devices--a stiff spring kappa coupled with a Voigt element that includes a less stiff spring k and a dashpot gamma--has been improved by adding a new element to describe the main features of the contraction of axons. This element, which represents the action of molecular motors, acts in parallel with viscous forces defining a global tension response of axons T against elongation rates delta(k). Under certain conditions, axons show a transition from a viscoelastic elongation to active contraction, suggesting the presence of a negative elongation rate sensitivity in the curve T vs delta(k).
Bernal
Roberto
R
Departamento de Física, Universidad de Santiago de Chile, and CIMAT, Correo 2, Santiago, Chile.
Pullarkat
Pramod A
PA
Melo
Francisco
F
D000818:Animals; D001369:Axons / Q000378:metabolism*; D004548:Elasticity; D016501:Neurites / Q000378:metabolism; D016716:PC12 Cells; D051381:Rats; D014783:Viscosity