Figure 2.
Electrical coupling between stratum lacunosum-moleculare interneurons is modulated by β-adrenergic receptors. A, Application of noradrenaline (20 μm) reduces the estimated Gj (for details, see Materials and Methods) and the cc. The time course of the effect of noradrenaline on the normalized cc, Gj (n = 14 bidirectional connections), and Rinput (n = 14 neurons; absolute values were 213 ± 24 MΩ in control vs 188 ± 24 MΩ in the presence of noradrenaline) are shown in the left plots, whereas the change in absolute values of Gj and cc (n = 14 bidirectional connections) are shown in the right summary graphs (Ctrl, control). Error bars are SEM. The top insets show averaged traces recorded from the cells of a pair showing the decreased propagation of an electrotonic response. The voltage response in the current injected cell (V1) is shown in millivolts, whereas the propagated response in the noninjected neurons (V2) is displayed as percentage of the steady-state value of V1. B, Panels are organized as in A, but the effect of selective β-adrenergic receptor agonist isoproterenol (Iso) (10 μm) is shown. Notice the large reduction of coupling and estimated junctional conductance after application of the drug (n = 10 bidirectional connections; Rinput was 209 ± 16 MΩ in control vs 205 ± 18 MΩ in the presence of isoproterenol; n = 10 neurons).