β-Receptor activation depolarizes ET cells and increases rhythmic bursting. A1: example ET cell current-clamp recording shows that Isop (10 μM) reversibly depolarizes and increases its burst frequency in the presence of APV-CNQX-gabazine and the ET cell is fully recovered upon 14-min washout (∼10–17 min, 7 ET cells). A2: faster timescale traces taken from points a–c in A1. B: diagram shows burst parameters. Note that trace was from cell in A1 in control and with application of Isop and the spikes were truncated. C: group data from 8 ET cells show that Isop significantly increased the burst rate, number of spikes/burst, and firing frequency. D: group data from 8 ET cells show that Isop increased the amplitude and rising phase slope of the slow depolarizing envelope, as well as the burst duration. *P < 0.01 vs. Control (n in parentheses), paired t-tests. MMP, minimal membrane potential.