Perilymph contains:

(a) Na+(Ref. Shambaugh, 6th ed., page 79)Perilymph is the fluid which fills the bony labyrinth.Perilymph is actually an extension of CSF which enters from the subarachnoid space into the scala tympani through Cochlear aqueduct.CSF being an extracellular fluid therefore perilymph is rich in Na+.Endolymph filling the membranous labyrinth and secreted from stria vascularis is rich in K+.