Differential effect of cyclo-oxygenase inhibition on antigen- and ionophore-induced release of slow reacting substance from fragmented guinea-pig lung

The effect of ketoconazole on pulmonary pathology associated with dead Dirofilaria immitis

The involvement of thromboxane and lipoxygenase in the regulation of pulmonary lesions and immune responses was investigated in dogs given ketoconazole and exposed to dead adult Dirofiliara immitis. Immunopathological reactions to the dead filariae were monitored by light and transmission electron microscopy and serology. When compared with control tissues, ketoconazole administration enhanced the level of pulmonary haemorrhage and early parenchymal fibrosis associated with dead adult filariae. Ultrastructurally, alveolar capillaries were filled with erythrocyte aggregations and proteinaceous material. These results suggested that an intact thromboxane and lipoxygenase pathway within the arachidonic acid system is necessary to minimize the effect of dead D. immitis in this pulmonary artery model.

Biochemical and pharmacological characterization of ICI 198,615: a peptide leukotriene receptor antagonist

ICI 198,615 is one representative of a new chemical class of peptide leukotriene receptor antagonists that are the most potent and selective described to date. ICI 198,615 antagonized LTC4-, LTD4- and LTE4-induced increases in cutaneous vascular permeability in the guinea pig, with i.v. ED50 values of 0.083, 0.11 and 0.067 mumol/kg, respectively. Against LTD4, ICI 198,615 was 615 and 415 times more potent than LY 171883 and FPL 55712, respectively. L-Serine borate, an inhibitor of the metabolism of LTC4 to LTD4, did not influence the antagonism by ICI 198,615 of LTC4-induced increases in cutaneous vascular permeability. The compound both inhibited and reversed aerosol ovalbumin antigen-induced increases in pulmonary resistance in passively sensitized guinea pigs, but demonstrated little ability to inhibit or reverse ovalbumin antigen-induced decreases in dynamic lung compliance. At concentrations ranging from 10(-8) to 10(-5) M, ICI 198,615 had no significant effect on either the spontaneous or ovalbumin antigen-induced release of histamine, peptide leukotrienes, thromboxane B2 or 6-keto-prostaglandin F1 alpha from chopped guinea pig lung. At 10 microM, the compound did not inhibit 5-, 12- or 15-lipoxygenase. Finally, ICI 198,615 antagonized LTD4-induced increases in TxB2 release from chopped guinea-pig lung.

Phagocytosis and metabolism of alveolar macrophages of guinea pigs treated with Haemophilus influenzae

Previously we showed that guinea pig alveolar macrophages (AMs) incubated with serum obtained from Haemophilus influenzae-treated animals had detrimental effects on airway smooth muscle beta-adrenergic receptor function. In the present study the influence of H. influenzae treatment on several functions of guinea pig AMs was examined. Sera obtained from animals 4 days after intraperitoneal administration of H. influenzae or from control guinea pigs possessed similar opsonic capacities. No effects of these sera on hydrogen peroxide release by AMs were observed as compared to the basal hydrogen peroxide release of AMs. Interestingly, stimulation of AMs with serum from control animals resulted in a diminished cyclo-oxygenase product formation, which was potentiated after incubating AMs with serum from H. influenzae-treated guinea pigs. No differences in phagocytic activity of AMs isolated from control or H. influenzae-treated animals were observed. When AMs were incubated with phorbol myristate acetate or zymosan, the cells produced superoxide anion and released hydrogen peroxide. However, the amounts of superoxide and hydrogen peroxide released did not differ between AMs isolated from control or H. influenzae-treated animals.

The synthesis of eicosanoids induced by anaphylaxis in guinea-pig isolated lungs perfused via the trachea

We have monitored the release of prostanoids and leukotrienes from isolated lungs taken from previously sensitized guinea-pigs perfused either via the pulmonary artery or via the trachea. The eicosanoids were monitored by direct radioimmunoassay and further identified by bioassay and radioimmunoassay following separation by RP-HPLC. When ovalbumin is delivered via the trachea it releases more cyclo-oxygenase products (3-fold) and lipoxygenase products (10-fold) than when delivered via the pulmonary circulation. Indomethacin enhanced leukotriene release whereas BW755C did not affect the release of leukotrienes induced by ovalbumin. These results suggest that perfusing the lungs via the trachea might be relevant for the study of anaphylaxis and other conditions in which the pathophysiological development is determined by cells closer to the alveolar surface in the lung.