Involvement of calcium ions in the mode of action of disodium cromoglycate and ketotifen on smooth muscle.

The mechanism of inhibitory action of disodium cromoglycate (DSCG) and Ketotifen (Ke) on smooth muscle against various spasmogens remains uncertain. In an attempt to elucidate it, we have studied the effects of both drugs on cumulative dose response curves (CDRC) to CaCl2 in guinea pig ileum. We found that they induce a shift to the right and a non surmountable depression of the maximal response of these CDRC which suggests non competitive antagonism. Furthermore, DSCG inhibits 45Ca++ uptake by guinea pig ileum after acetylcholine stimulation which constitutes strong evidence that inhibition of calcium ion utilization by smooth muscle cells plays a major role in the mode of action of DSCG.