Structure-Activity Relationships of Neurokinin A and B
Neurokinin A (NKA) and neurokinin B (NKB) are newly discovered mammalian neuropeptides, the chemical structures of which are closely related to tachykinin peptides (1). Both neurokinins have qualitatively the same pharmacological properties, such as contraction of smooth muscles, hypotensive effect and salivation (2). The peptides also possess electrophysiological characteristics like substance P (SP) though the efficacies are not equal (2,3). Furthermore, at least NKA is considered to be involved in pain transmission as is SP (4).