mAChR activation increases [Ca2+]i. A: muscarinic agonists ACh (10 μM, n = 22 cells), muscarine (10 μM, n = 11 cells), and oxotremorine methiodide (OxoM; 20 μM, n = 43 cells) increase intracellular calcium concentration. Responses are reduced or blocked by incubation with the muscarinic antagonist atropine methyl nitrate (AMN; 10 μM). *Significant differences (P < 0.05) tested with paired t-test. Data were collected from 3–12 coverslips from 3–5 cultures. B: concentration-response curve of OxoM-elicited [Ca2+]i changes. Data were fitted with a logistic curve described by the equation y = A2 + (A1 − A2)/[1 + (x/x0)ˆp] (see MATERIALS AND METHODS). A1 was 9.88 ± 2.62, A2 was 21.74 ± 1.48, X0 or EC50 was 5.33 ± 2.31E−8, and P was 2.95 ± 4.32. Data were collected from 4–12 coverslips from 3–5 cultures (Table 3). C: example from a single urothelial cell of [Ca2+]i increases evoked by repetitive applications of OxoM (20 μM). R = F340nm/F380nm which is proportional to the intracellular calcium concentration.