In nonexcitable cells, Ca2+ entry is mediated predominantly through the store depletion-dependent Ca2+ channels called store-operated Ca2+ (SOC) or Ca2+ release-activated Ca2+ channels. YM-58483, a pyrazole derivative, inhibited an anti-CD3 mAb-induced sustained Ca2+ influx in acute T cell leukemia, Jurkat cells. But it did not affect an anti-CD3 mAb-induced transient intracellular Ca2+ increase in Ca2+-free medium, nor anti-CD3 mAb-induced phosphorylation of phospholipase Cγ1. It was suggested that YM-58483 inhibited Ca2+ influx through SOC channels without affecting the TCR signal transduction cascade. Furthermore, YM-58483 inhibited thapsigargin-induced sustained Ca2+ influx with an IC50 value of 100 nM without affecting membrane potential. YM-58483 inhibited by 30-fold the Ca2+ influx through SOC channels compared with voltage-operated Ca2+ channels, while econazole inhibited both SOC channels and voltage-operated Ca2+ channels with an equivalent range of IC50 values. YM-58483 potently inhibited IL-2 production and NF-AT-driven promoter activity, but not AP-1-driven promoter activity in Jurkat cells. Moreover, this compound inhibited delayed-type hypersensitivity in mice with an ED50 of 1.1 mg/kg. Therefore, we concluded that YM-58483 was a novel store-operated Ca2+ entry blocker and a potent immunomodulator, and could be useful for the treatment of autoimmune diseases and chronic inflammation. Furthermore, YM-58483 would be a candidate for the study of capacitative Ca2+ entry mechanisms through SOC/CRAC channels and for identification of putative Ca2+ channel genes.

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The pharmacological profile of celecoxib (CAS 169590-42-5, SC-58635), a specific cyclooxygenase-2 (COX-2) inhibitor, was investigated. Celecoxib inhibited COX-2-mediated prostaglandin E2 (PGE2) production in human dermal fibroblasts (IC50 = 91 nmol/l), whereas it was a weak inhibitor of COX-1-mediated PGE2 production in human lymphoma cells (IC50 = 2800 nmol/l). In in vivo studies, the effects of celecoxib were compared with those of nonsteroidal anti-inflammatory drugs (NSAIDs) in acute rat models of hyperalgesia and pyrexia. Celecoxib abrogated carrageenan-induced hyperalgesia in the hind paw accompanied by a decrease in PGE2 content in paw exudates and cerebrospinal fluid in a dose-related manner, with an ED30 = 0.81 mg/kg. Its analgesic potency was comparable to those of NSAIDs. In lipopolysaccharide-induced pyrexia, the anti-pyretic potency of celecoxib was equal to that of NSAIDs. On the other hand, in a gastric toxicity study in rats, single oral administration of celecoxib had no effect on gastric mucosa or mucosal PGE2 content at doses up to 200 mg/kg. Additionally, celecoxib did not inhibit thromboxane B2 production of calcium ionophore-stimulated peripheral blood of rats or arachidonic acid-induced aggregation of human platelets. These findings suggest that celecoxib might be a safe and effective alternative to NSAIDs for clinical use.