Figure 7.

Isoproterenol-induced modulation of coupling depends on the activity of adenylyl cyclase and PKA. A, Application of isoproterenol (10 μm) after exposure to MDL12330A (10 μm) fails to depress coupling. Summary graphs of normalized G_j, normalized cc (n = 10 bidirectional connections), and normalized R_input (n = 10 cells; actual values were 274 ± 17 MΩ in control, 265 ± 22 MΩ in MDL12330A, and 245 ± 23 MΩ in MDL12330A and isoproterenol) are shown in the middle, whereas actual values are illustrated at the bottom (Ctrl, control; MDL, MDL12330A; MDL+ISO, MDL12330A plus isoproterenol). Error bars are SEM. The top insets show averaged traces from a recorded pair in the three different conditions. V₁ indicates the voltage responses from the current-injected cell, whereas V₂ indicates the propagated responses. Responses from the current-injected neuron are shown in millivolts, whereas propagated responses are expressed as percentage of the steady-state value of V₁. B, Isoproterenol-induced modulation of coupling is prevented by the inclusion of KT5720 in the recording pipettes. Notice that no effects are present either on G_j or cc. The time course of the normalized G_j, cc (n = 12 bidirectional connections), and R_input (n = 12 neurons) are shown at the left, whereas the actual values are shown in the right summary plots. Error bars are SEM. R_input was 204 ± 18 MΩ in control versus 156 ± 19 MΩ after the addition of isoproterenol (n = 12 cells). The top insets show averaged traces from the injected cell (V₁) and noninjected cell (V₂) of the pair before and after application of isoproterenol.