PubMed · 156620
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C D Calnan. 1979. Chloracetophenone (CS) dermatitis.. https://doi.org/10.1111/j.1600-0536.1979.tb04847.x
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To compare the receptors for cysteinyl-leukotriene (cys-LT) in rat skin with those in other tissues, we investigated the effects of specific cys-LT receptor antagonists (FPL 55712, LY171883, MCI-826 and L-648051) on cys-LT-induced cutaneous reactions in rats and mice, and on cys-LT-induced contractile responses in rat stomach smooth muscle. We also studied the effects of these drugs on homologous passive cutaneous anaphylaxis. The four cys-LT receptor antagonists dose dependently inhibited cys-LT-induced cutaneous reactions in mouse ear, but failed to inhibit passive cutaneous anaphylaxis and the histamine-induced cutaneous reaction. In rats, only MCI-826 inhibited cys-LT-induced cutaneous reactions although the other three drugs failed to inhibit these reactions. In contrast, the cys-LT-induced contractile responses of rat stomach smooth muscle were inhibited by all these drugs in a concentration-dependent manner. These results suggest that cys-LT receptors in rat skin have an affinity different from that of receptors in mouse skin and rat stomach. They also suggest that cys-LTs are not involved in passive cutaneous anaphylaxis in mice and rats.
Phospholipase activation is an important element in cellular signal transduction. In our study we investigated the role and regulation of phospholipase activation during human monocyte adherence and spreading. In human monocytes, phospholipase inhibition (with bromophenacyl bromide (BPB) or manoalide) impaired cell adherence and spreading. In contrast, neither cyclooxygenase/lipoxygenase inhibition nor platelet activating factor receptor blockade affected these responses. The impaired adherence and spreading induced by phospholipase inhibition with BPB could be partially reversed by the addition of nM levels of arachidonate (20:4(n - 6)). Dihomogammalinolenic acid (20:3(n - 6)) could substitute for arachidonate, but other polyunsaturated fatty acids were ineffective in this regard. The phospholipase inhibitor, BPB was selective in its effects on cellular phospholipase activities. BPB inhibited adherence/spreading-related and PMA-stimulated phospholipase activities, but not Ca2+ ionophore-stimulated phospholipase activity. To further probe for the role of Ca2+ in monocyte adherence and spreading, monocytes were loaded with MAPTAM (bis-(2-amino-5-methylphenoxy)-ethane-N,N,N',N', tetraacetic acid tetraacetoxymethyl ester), an EGTA analog. In contrast to phospholipase inhibition, intracellular Ca2+ chelation with MAPTAM did not affect monocyte adherence but did inhibit monocyte spreading. MAPTAM partially inhibited adherence/spreading-stimulated phospholipase activity, but did not inhibit PMA-stimulated phospholipase activity. These data suggest that human monocyte adherence and spreading may sequentially activate Ca(2+)-independent and then Ca(2+)-dependent phospholipases to release arachidonate. The activation of phospholipase and the release of arachidonate appear to be integral parts of the adhesion process.