Studies on stimulus-response coupling in human neutrophils. II. Relationships between the effects of changes of external ionic composition on the properties of N-formylmethionylleucylphenylalanine receptors and on the respiratory and secretory responses.
Studies were carried out on the mechanism responsible for the enhancement of the respiratory and secretory responses to N-formylmethionylleucylphenylalanine (fMet-Leu-Phe) exhibited by human neutrophils suspended in Na+-free, high-K+ buffered solution. The results demonstrate that: (a) the variation of Na+ concentration in the suspending solution induces in human neutrophils a marked modification of the recognition apparatus for the chemotactic peptide fMet-Leu-Phe, the lack of or low concentration of this ion increasing the number of the receptors and their specific affinity for the ligand; (b) the greater respiratory burst and secretion induced by fMet-Leu-Phe in human neutrophils suspended in Na+-free, high-K+ medium are due to the increased formation of receptor-ligand complexes at the cell membrane; (c) the greater respiratory response is partially due also to a higher efficiency of these receptor-ligand complexes. The molecular mechanism by which Na+ exerts a regulative role on the properties of the recognition apparatus for the chemotactic peptide and its possible significance are discussed.
D002414:Cations, Monovalent / Q000494:pharmacology*; D004151:Dipeptides / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D008715:Methionine / Q000031:analogs & derivatives*; D009239:N-Formylmethionine / Q000031:analogs & derivatives* / Q000494:pharmacology; D009240:N-Formylmethionine Leucyl-Phenylalanine; D009504:Neutrophils / Q000187:drug effects* / Q000378:metabolism; D009842:Oligopeptides / Q000494:pharmacology*; D010101:Oxygen Consumption / Q000187:drug effects; D011955:Receptors, Drug / Q000187:drug effects; D013997:Time Factors
D002414:Cations, Monovalent; D004151:Dipeptides; D009842:Oligopeptides; D011955:Receptors, Drug; C017330:N-formylmethionylphenylalanine; D009239:N-Formylmethionine; D009240:N-Formylmethionine Leucyl-Phenylalanine; D008715:Methionine