Microtubule-neurofilament segregation produced by beta, beta'-iminodipropionitrile: evidence for the association of fast axonal transport with microtubules.

The subperineurial injection of beta,beta'-iminodipropionitrile (IDPN) into rat sciatic nerves resulted in focal disorganization of the axonal cytoskeleton characterized by segregation of neurofilaments and microtubules. Shortly after injection, microtubules clustered together to form a central channel, while neurofilaments became chaotically arrayed between the microtubule channel and axolemma. Electron microscopic autoradiography disclosed that rapidly transported organelles were preferentially associated with the microtubule-enriched central channels. These studies indicate that IDPN acts at the level of the axon to disrupt interactions between cytoskeletal elements and show that rapidly transported constituents are preferentially conveyed in association with microtubules. The model provides an opportunity to dissect the interactions of the cytoskeletal elements and other organelles.