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  • 1
    ISSN: 1432-1912
    Keywords: Somatostatin ; Octreotide ; Neutrophils ; Raspiratory burst ; Chemotaxis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Growth hormone, prolactin and somatostatin are polypeptide hormones of the neuroendocrine and peripheral nervous systems. In vitro, these have opposing effects on cells of the immune system. We compared the effects of these peptides on activation of neutrophils using a recombinant preparation of human growth hormone, human prolactin and octreotide, a long acting analog of somatostatin. In the absence of growth hormone, octreotide did not affect either neutrophil locomotion or respiratory burst. Octreotide, however, significantly antagonized growth hormone-induced activation of neutrophils for enhanced respiratory burst as well as growth hormone-induced inhibition of stimulated migration. As the effect of growth hormone on neutrophils is mediated by the prolactin receptor, its inhibition by octreotide was also tested using prolactin as priming agent. Data indicate comparable effects of octreotide on priming of neutrophils by prolactin. The effect of octreotide was dose-dependent and appeared to be selective, as activation of neutrophil respiration burst by γ-interferon, and inhibition of stimulated migration by tumor necrosis factor-α were unaffected by octreotide. The present study suggests that octreotide may act on neutrophils directly by antagonizing growth hormone or prolactin at the cellular level.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1440
    Keywords: Nitric oxide ; Respiratory burst ; Ischemia ; Reperfusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In animal studies of myocardial ischemia/reperfusion l-arginine reduces necrotic injury by preservation of endothelial function and attenuation of neutrophil accumulation in ischemic cardiac tissue. Because release of oxygen radical species by circulating neutrophils is important in endothelial function and ischemia-reperfusion injury, this study investigated the effect of intravenous administration of L-arginine on the in vitro release of superoxide anion of neutrophils in healthy young adults. Neutrophils were obtained at various time points before, during, and after infusion of l-arginine (17 mg kg−1 min−1 for 30 min) and analyzed for superoxide dismutase inhibitable reduction of ferricytochrome c. The spontaneously occurring respiratory burst of polymorphonuclear leukocytes at basal conditions was compared with that after triggering by 1 μmol/l formylpeptide or 50 ng/ml phorbolester. Infusion of l-arginine inhibited both basal (P 〈 0.01) and formylpeptide-triggered (P 〈 0.05) release of superoxide anion did, but not affect release stimulated by phorbol 12-myristate 13-acetate. Pretreatment of neutrophils with 1 mmol/l l-arginine in vitro also significantly reduced formylpeptide-triggered (1 μmol/l) superoxide anion release, suggesting that the affects observed after in vivo pretreatment may be due to direct action of l-arginine on neutrophils. These findings demonstrate the ability of L-arginine to reduce release of oxygen radical species by circulating neutrophils in man.
    Type of Medium: Electronic Resource
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