Evidence for a direct relationship between phosphoinositide metabolism and airway smooth muscle contraction induced by muscarinic agonists

The relationship between bovine tracheal muscle contraction and phosphoinositide metabolism was studied with the muscarinic agonists, methacholine, oxotremorine, and McN-A-343. Analysis of the dose-response curves for contraction and inositol phosphates accumulation with these agonists demonstrated a direct relationship between the two parameters, with a considerable reserve of inositol posphate production for the full contractile agonists, methacholine and oxotremorine, and no reserve for the partial agonist, McN-A-343.