Chand N, Diamantis W, Sofia R D
Br J Pharmacol. 1987 May;91(1):17-22. doi: 10.1111/j.1476-5381.1987.tb08978.x.
The effect of antigen challenge on cold provocation (30-10 degrees C) in isolated tracheal segments from control (normal) and ovalbumin-sensitized rats was studied. Sensitization alone or acute cold provocation (10 degrees C) alone was not sufficient to cause contraction of tracheal smooth muscle preparation. Following recovery from antigen-induced responses (Schultz-Dale phenomenon) in sensitized rat segments, cold provocation induced strong contractile responses. Both the antigen-induced contractions and the subsequent development of airway hyperreactivity to cold were dependent on extracellular Ca2+ and inhibited by verapamil. The data in this study indicate that extracellular Ca2+ plays an obligatory role in the mediation of antigen-induced contractile responses as well as the subsequent development of hyperreactivity to cold provocation in rat tracheal smooth muscle.