The contractile activities of neurokinin A, B and related peptides on smooth muscles.
The contractile activities of neurokinin A (NKA), neurokinin B (NKB) and related peptides on the guinea-pig ileum, rat vas deferens and rat duodenum were compared to the activity of substance P (SP). The potencies of NKA and NKB on the guinea-pig ileum (SP-P tissue) were nearly the same as that of SP. NKA was approximately 250-400 times more potent than SP on the rat vas deferens (EC50 = 59.5 nM; SP, EC50 = 1500 nM) and rat duodenum (EC50 = 1.8 nM; SP, EC50 = 674 nM) (SP-E tissues). NKB also showed high contracting activity on the rat duodenum (EC50 = 3.1 nM) but was 10 fold less active than NKA on the rat vas deferens. These results suggest that neurokinin peptides are possible endogenous agonists for the SP-E tissues. The contractile potency of NKA and NKB remained nearly complete after removal of N-terminal tripeptide portions, i.e., His-Lys-Thr and Asp-Met-His from the native peptides, respectively. However, the removal of the Asp residue from both NKA7 and NKB7 decreased activity until it was similar to that of SP.
F
F
Osakada
K
K
Kubo
K
K
Goto
I
I
Kanazawa
E
E
Munekata
D000595:Amino Acid Sequence; D000818:Animals; D004386:Duodenum / Q000187:drug effects; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects*; D009419:Nerve Tissue Proteins / Q000494:pharmacology*; D015288:Neurokinin A; D015287:Neurokinin B; D009842:Oligopeptides / Q000494:pharmacology*; D051381:Rats; D013329:Structure-Activity Relationship; D013373:Substance P / Q000494:pharmacology; D014649:Vas Deferens / Q000187:drug effects
D009419:Nerve Tissue Proteins; D009842:Oligopeptides; D013373:Substance P; D015288:Neurokinin A; D015287:Neurokinin B