抄録
Leukocytes participate in inflammatory reaction by stimulus-linked release of granules and by synthesis of prostaglandins. Blood platelets are also circulating secretory cells and we have recently demonstrated that phenothiazines known as inhibitors of calmodulin inhibit stimulus-linked platelet reaction by blocking release of arachidonic acid from membrane phospholipids. Considering similarity of these cells, the effect of phenothiazines on the stimulus-linked release reaction of neutrophils was investigated. Rabbit neutrophils were obtained according to the method of Becker and Showell. Release reaction was triggered by addition of synthetic peptide FMLP to washed neutrophils pretreated with cytochalasin B. β-glucuronidase and lysozyme were measured as markers of lysosomal enzyme. Also lactate dehydrogenase (LDH) was assayed as an indicator of cellular destruction. 10 μM of FMLP was able to induce rapid release of two lysosomal enzymes assayed without significant release of LDH. About 60% of total enzymes were released within 1 minute after the addition of stimulus. Chlorpromazine hydrochloride (CPZ) or promethazine hydrochloride (PMZ) was used as an inhibitor of calmodulin, each of which dose-dependently inhibited the release of lysosomal enzymes. The complete inhibition of the release was observed by either 100 μM CPZ or 200 μM PMZ. In conclusion, we have demonstrated that phenothiazines inhibit FMLP stimulated release reaction of neutrophils, indicating the involvement of calmodulin in the reaction. The exact mechanism of the inhibition, however, has yet to be elucidated.
