INHIBITORY EFFECTS OF CAFFEINE ON CA2-SECRETION INDEPENDENT OF CAMP IN RAT PERITONEAL MAST-CELLS( INFLUX AND HISTAMINE)

1. Caffeine did not evoke Ca2+ mobilization and histamine secretion. 2 . Caffeine, as well as other methylxanthines but not forskolin or 8 br omo-cAMP, inhibited Ca(2+)responses from compound 48/80. 3. Evoked his tamine secretion was severely reduced by caffeine but not by cAMP anal ogs. 4. In beta-escin-permeabilized cells, caffeine did not affect res ting and IP3-stimulated Ca-45(2+) release, but it inhibited Ca2+-induc ed histamine secretion. 5. These results indicate that caffeine inhibi ts Ca2+ influx and Ca2+ efficacy in the secretory apparatus independen t of cAMP, resulting in the inhibition of secretagogs-evoked histamine secretion from rat mast cells. Copyright (C) 1997 ELsevier Science In c.