Abstract
The actions of the antiallergic agents, disodium chromoglycate (DSCG), tranilast and ketotifen, and of a calcium channel antagonist, nicardipine, and cross-reactivity among the agents were examined by observing the inhibition of45Ca uptake and histamine release in rat mast cells stimulated by antigen and compound 48/80 (comp. 48/80). 1) All agents inhibited45Ca uptake and histamine release in mast cells stimulated by antigen. The inhibition of45Ca uptake by the antiallergic agents paralleled the inhibition of histamine release, while nicardipine inhibition of45Ca uptake was stronger than its inhibition of histamine release. 2) The action of DSCG on45Ca uptake and histamine release was significantly decreased in cells stimulated with antigen and phosphatidylserine (PS), while tranilast inhibition of histamine release was not affected by the addition of PS despite a significant decrease in the inhibition of45Ca uptake. 3) The inhibitory effect of DSCG and tranilast was significantly lower in mast cells stimulated by comp. 48/80 than in the cells stimulated by antigen. 4) Tachyphylaxis was observed in cells re-exposed to DSCG and tranilast following previous exposure to the agents. 5) Cross-reactivity was found between DSCG and tranilast.