Figure 6.

(A) Effects of graded concentrations of SP on desensitization of SP-induced Ca²⁺ mobilization in myenteric neurons. Neurons were exposed to graded concentrations of SP or carrier (control) for 5 min, washed, and then challenged with 100 nM SP 10 min later. The maximal increase in the 340:380 nm fluorescence ratio to the second SP exposure was determined. (B) Time course for resensitization of SP-induced Ca²⁺ mobilization. Neurons were exposed to 100 nM SP or carrier (control) for 5 min, washed, and then challenged with 100 nM SP 10, 20, or 30 min later. The maximal increase in the 340:380 nm fluorescence ratio to the second SP exposure was determined. Results are the mean ± SE of measurements from n = >100 neurons, and observations were repeated on at least three different coverslips at each agonist concentration.