Dyn-A (1–13) induced suppression of calcium oscillations is opioid receptor-mediated. A and B, 1 μM Dyn-A (1–17) produced a suppression of calcium oscillations, whereas 1 μM Dyn-A (2–17) did not affect calcium oscillations. C, summary histogram of data represent the mean ± S.E.M. (n = 4) of calcium oscillations (for 300 s) before and after compound addition. *, p < 0.01, paired t test between the average number of oscillations before and after the addition of Dyn-A (1–17) 1 μM and Dyn-A (2–17) 1 μM.