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The influence of 12-O-Tetradecanoylphorbol-13-acetate, an activator of proteinkinase C and A 23187, a calcium ionophore increasing cytosolic free calcium concentration on zinc metabolism was investigated in a study with 24 eight-week old rats. Twenty-four hours before killing, the rats (235 g body weight, 8 per group) were either injected intraperitoneally with TPA (1.6 x 10(-7) mol/kg body weight) or A 23187 (1.6 x 10(-6) mol/kg body weight). Control rats received the solvent dimethylsulfoxide. The application of TPA and A 23187 provoked a marked decline in feed intake accompanied by a reduction in body weight and liver mass. Serum concentrations of zinc were reduced significantly after A 23187 injections. TPA and A 23187 increased liver zinc levels by 20 and 30% respectively, if based on fresh and dry weight. The injections, however, did not alter total liver zinc. Liver metallothionein (MT) concentration was elevated 2.4-fold after TPA administration. The increase in response to A 23187 was only 1.5-fold and not significant. Mucosa MT levels were not altered. Serum activity of alkaline phosphatase was significantly reduced (TPA: -23%, A 23187: -31%). There was no change in serum glucose after injections. However, serum creatinine and urea were increased in response to A 23187. In conclusion, TPA and A 23187 had an effect on zinc metabolism of the rat, most marked in the case of MT induction in the liver. There is evidence that the reduced feed intake caused by TPA and A 23187 resulted in effects indistinguishable from those caused by fasting. Further experiments are needed to clarify whether proteinkinase C and cytosolic free calcium are directly involved in the regulation of zinc metabolism.

Alveolar macrophages of normal and endotoxin--treated rats were stimulated in suspension by calcium ionophore A 23187. After solid phase extraction and isocratic separation by HPLC the lipoxygenase products (Leukotriene B4, 5-hydroxyeicosatetraenoic acid and 12-hydroxyeicosatetraenioc acid) were quantified. Unlike alveolar macrophages of control animals, alveolar macrophages of endotoxin treated rats showed an increased synthesis of lipoxygenase products (Leukotriene B4: 1.6fold; 5-hydroxyeicosatetraenoic acid: 2.1fold; 12-hydroxyeicosatetraenoic acid: 1.3fold). Our results suggest that in vivo endotoxin disturbs the mechanisms of arachidonic acid liberation in alveolar macrophages.

In the model of isolated, ventilated and perfused rabbit lungs release of arachidonic acid results in an increase of pulmonary vascular resistance and permeability. The former can be ascribed to cyclooxygenase products, the latter to lipoxygenase products of arachidonic acid. The effect of alpha-tocopherol on the increase of pulmonary vascular resistance and permeability either after the addition of arachidonic acid to the perfusion fluid or after stimulation of arachidonic acid liberation by Ca-ionophore A 23187 was investigated. It is possible to distinguish a membrane effect of the phytol side chain of alpha-tocopherol and an antioxidative effect of its chromane structure: Phytol augments the increase of pulmonary vascular resistance and permeability, whereas the chromane-structure decreases both to a large degree. The possibility of antioxidative therapy in disturbances of pulmonary vascular permeability is discussed.

Tissues of the gastrointestinal tract synthesize leukotriene (LT) B4 and the sulfidopeptide-leukotrienes LTC4, LTD4 and LTE4 from endogenous substrate. Formation of leukotrienes was demonstrated using radioimmunoassay, high pressure liquid chromatography (HPLC) and bioassay. Under basal conditions the gastrointestinal tissues released minor amounts of leukotrienes only. Formation of lipoxygenase-derived products of arachidonic acid metabolism was, however, significantly increased in the presence of various stimuli. Thus, significant amounts of LTB4 and of sulfidopeptide-leukotrienes were released from colonic and gastric mucosa of guinea-pigs sensitized against ovalbumin when incubations were carried out in the presence of antigen. Antigen-induced leukotriene formation was not found in the muscularis propria and subserosal of ovalbumin-sensitized guinea-pigs. Release of cyclooxygenase-derived metabolites of arachidonic acid, on the other hand, was most abundant in the subserosal layer of the guinea-pig colon and was not influenced by the immunological reaction. Inhibitors of cyclooxygenase, such as indomethacin, reduced gastrointestinal formation of prostaglandins, but not of leukotrienes. Inhibitors of 5-lipoxygenase, however, significantly decreased leukotriene formation. Synthesis of LTB4 and of sulfidopeptide-leukotrienes was also found in human colonic mucosal tissue, using the divalent cation-ionophore A23187 as stimulating agent. HPLC analysis demonstrated that the sulfidopeptide-leukotrienes released were composed of a mixture of LTC4, LTD4 and LTE4. In addition, human colonic mucosal tissue contained high activities of enzymes that rapidly convert LTC4 to LTE4. As in most biological systems LTE4 is less active than LTC4 and LTD4 degrading enzymes might represent a local inactivating mechanism. Mucosal tissue of patients with Crohn's disease synthesized considerably more LTB4 and sulfidopeptide-leukotrienes than non-inflamed mucosa.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of benzydamine (Tantum) on the aggregation of rat leukocytes was compared to some commonly used nonsteroidal antiinflammatory drugs (NSAID). The aggregation response was induced by various activators such as the tumour promoter phorbol myristate acetate, the chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (FMLP), arachidonic acid, sodium arachidonate, platelet activating factor (PAF) and a combination of cytochalasin B and Ca++-ionophore A 23187. As compared to indomethacin, piroxicam and acetylsalicylic acid benzydamine was inhibitory against most of the activators, i.e. the receptor-mediated induction of the aggregation by FMLP, the phorbol ester and sodium arachidonate. No effect could be observed against PAF induced aggregation. Under the assay conditions benzydamine exerted cytolytic effects at 2 X 10(-4) mol/l. Cytolysis reached 100% at 5 X 10(-4) mol/l benzydamine, as could be shown microscopically and by measurement of free cytosolic lactate dehydrogenase. Thus benzydamine exerted a broad spectrum inhibitory activity against rat leukocyte aggregation, possibly explained by its unspecific membrane affinity.