Effect of N-formyl-L-methionyl-L-leucyl-L-phenylalanine and its analogues on blood pressure.

Effects of N-formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP), the synthetic chemotactic peptide, and its analogues on blood pressure were investigated in the rabbit, rat, mouse, dog, cat and guinea pig. The administration of FMLP (5 micrograms/kg i.v.) induced the depressor effect in the rabbit but no effect was observed in the other animal species. The only peptide which showed a similar effect as FMLP was N-formyl-L-methionyl-L-methionyl-L-phenylalanine (FMMP) among the peptides relating to FMLP. Tachyphylaxis was observed in the hypotensive action induced by the two peptides.