Substance P: a carotid body peptide.

Immunofluorescent studies have shown that substance P or substance P-like material is present in the cat carotid body, being located in some of the glomus cells and also in nerve axons. About 20% of the glomus cells were substance P positive. Substance P may be stored in glomus cells containing monoamine(s), but further studies are needed to investigate this aspect and also to determine what role, if any, substance P plays in the process of chemoreception.