Endolymph's the fluid contained in the membranous labyrinth of the inner ear. It's also called Scarpa's fluid, after Antonio Scarpa. Composition The main cation of this unique extracellular fluid's potassium, which's secreted from the stria vascularis. The high potassium content of the endolymph means that potassium, not sodium,'s carried as the depolarizing electrical current in the hair cells. This's known as the mechano-electric transduction (MET) current. Endolymph has a high positive cha… (More on Endolymph)