RT Journal Article SR Electronic T1 Permeability of the Paranodal Junction of Myelinated Nerve Fibers JF The Journal of Neuroscience JO J. Neurosci. FD Society for Neuroscience SP 15962 OP 15968 DO 10.1523/JNEUROSCI.4047-10.2010 VO 30 IS 47 A1 Amanda Mierzwa A1 Seema Shroff A1 Jack Rosenbluth YR 2010 UL http://www.jneurosci.org/content/30/47/15962.abstract AB We have used fluorescent dextran tracers to test the tightness of the paranodal junction of living or fixed myelinated fibers in mouse sciatic nerve. Both 3 and 70 kDa tracers are able to penetrate from the perinodal space symmetrically into the paranodes on either side of the node of Ranvier at a rate consistent with diffusion through an elongated helical pathway between the paranodal terminal loops of the myelin sheath. This pathway thus provides an access route for movement of water soluble nutrients and metabolites to and from the internodal axon and constitutes a pathway through which juxtaparanodal potassium channels may be activated and may in turn affect nodal excitability. This pathway may also allow access of antibodies and toxic molecules to the internodal axon in paraneoplastic syndromes and demyelinating diseases.