Fig. 5.

Atropine and thapsigargin abolish noradrenaline-mediated Ca²⁺ responses in the presence of methacholine. a, using a FLIPR, cells were challenged with the indicated muscarinic receptor agonist (1 mM) in the presence or absence of 10 μM atropine before challenge with noradrenaline (10 μM). The graph shows the responses to noradrenaline in the presence of either muscarinic receptor agonists alone or muscarinic receptor agonists and atropine. b, cells were preincubated for 5 min in the presence or absence of thapsigargin (2 μM) before challenge with muscarinic receptor agonists (1 mM) and subsequently challenged with noradrenaline (10 μM). The graph shows only the responses to noradrenaline in the presence of muscarinic receptor agonists with or without thapsigargin treatment; the initial responses to methacholine are not shown. Data are mean + S.E.M., n = 3; ***, p < 0.0001, by Student's t test.