Dual modes of action for disodium cromoglycate in inhibition of antigen-induced contractions of guinea-pig isolated airways smooth muscle.

Disodium cromoglycate (DSCG; 10 mumol/l-1 mmol/l) relaxed the tone induced in the guinea-pig isolated trachea by histamine (5 mumol/l). Both isoprenaline and fenoterol were approximately 1000 times more potent than DSCG in relaxing tracheal smooth muscle. Ovalbumin (1 microgram/ml) contracted isolated tracheal and parenchymal strips from sensitized guinea-pigs. The sensitization procedure used was selective for eliciting IgG antibody production. In concentrations equieffective for relaxation of the isolated trachea, fenoterol (20 nmol/l), isoprenaline (60 nmol/l) and DSCG (100 mumol/l) inhibited ovalbumin-induced contractions of both tracheal and parenchymal strip preparations. DSCG produced a significantly greater (P less than 0.05) inhibition of ovalbumin-induced contractions of isolated trachea than did isoprenaline, suggesting that at 100 mumol/l DSCG produced a greater inhibition of mediator release than that produced by isoprenaline. Compound 48/80 (200 micrograms/ml) contracted the isolated trachea whereas this concentration had no contractile effect on the parenchymal strip. The failure of DSCG to inhibit compound 48/80 induced contractions of the isolated trachea together with the lack of contractile effect of compound 48/80 on the parenchymal strip suggest that compound 48/80 is inferior to antigenic stimulation as a reliable analogue of immunological activation of mast cells and consequent mediator release.(ABSTRACT TRUNCATED AT 250 WORDS)