Substance P-like immunoreactivity in the phrenic nerve and diaphragm: axonal transport of substance P in the phrenic nerve

Substance P-like immunoreactivity was demonstrated in the phrenic nerve of rat in quantities similar to that found in vagus and sciatic nerves. In the diaphragm, the peptide was concentrated in the motor endplate zone. A surgical cut of the phrenic nerve was followed by disappearance of substance P from the motor endplate zone. In addition we could demonstrate axonal transport of substance P in the phrenic nerve after transection of the nerve.