Calcium chelators increase airway responsiveness.
To test the effect of calcium chelation on airway responsiveness to methacholine, purebred Basenji dogs were pretreated with a calcium-chelating aerosol (edetate disodium, Na2EDTA) or a placebo aerosol (saline or CaNa2-EDTA) and then challenged with methacholine bromide aerosols. The lowest dose of methacholine (0.15 mg/ml) produced no change in pulmonary resistance (RL) following pretreatment with the placebo aerosols, but RL increased (P less than 0.05) by 5.1 +/- 1.2 (SE) cmH2O X l-1 X s following pretreatment with Na2EDTA. The highest dose of methacholine (1.5 mg/ml) increased RL in all animals, but the increase was greater (P less than 0.01) following pretreatment with Na2EDTA (9.5 +/- 1.9 cm H2O X l-1 X s) than following pretreatment with a placebo aerosol (6.4 +/- 1.5 cmH2O X l-1 X s). These studies show that calcium-chelating aerosols significantly increase airway responsiveness and suggest that a localized calcium deficit may contribute to hyperresponsive airway disease.
D000336:Aerosols; D000403:Airway Resistance / Q000187:drug effects; D000818:Animals; D001985:Bronchial Provocation Tests; D001986:Bronchial Spasm / Q000139:chemically induced*; D002118:Calcium; D002614:Chelating Agents / Q000494:pharmacology*; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D004492:Edetic Acid / Q000494:pharmacology*; D016210:Methacholine Chloride; D008688:Methacholine Compounds; D011292:Premedication
D000336:Aerosols; D002614:Chelating Agents; D008688:Methacholine Compounds; D016210:Methacholine Chloride; D004492:Edetic Acid; D002118:Calcium