Figure 8.
Blockade of protein kinase A abolishes β2-AR mediated enhancements of bAP-evoked spine Ca2+ transients. A, Ca2+ transients in spines and their parent dendrites in the presence of the PKA inhibitors KT5720 (KT; 3 μm), Rp-cAMPS and PKI (pipette concentrations of both 100 μm), and during additional activation of β2-ARs with salbutamol (40 μm). B, Percentage ratio of the Ca2+ transient amplitudes with salbutamol in the presence of a PKA inhibitor relative to Ca2+ transient amplitudes with PKA inhibitors alone. Ca2+ transient peak amplitudes did not change significantly during the first bAP (KT5720 spines, n = 4, NS, p = 0.39; KT5720 dendrites, n = 4, NS, p = 0.19; Rp-cAMPS spines, n = 3, NS, p = 0.09; Rp-cAMPS dendrites, n = 3, NS, p = 0.49; PKI spines, n = 4, NS, p = 0.18; PKI dendrites, n = 4, NS, p = 0.38) or the last bAP (KT5720 spines, NS, p = 0.36; KT5720 dendrites, NS, p = 0.44; Rp-cAMPS spines, NS, p = 0.15; Rp-cAMPS dendrites, NS, p = 0.27; PKI spines, NS, p = 0.24; PKI dendrites, NS, p = 0.18). B, Time course displaying the percentage change of the Ca2+ transient integrals with respect to control (no drug) in the presence of KT5720 (3 μm) and during additional activation of β2-ARs with salbutamol (40 μm). C, Percentage ratio of the Ca2+ transient integrals in the presence of KT5720, Rp-cAMPS, PKI, and salbutamol with respect to the integral in the presence of PKA inhibitors alone. Duringβ2-AR activation and with PKA blocked, Ca2+ transient integrals were not significantly different from integrals with PKA inhibitors alone, in both spines (KT5720, n = 4, NS, p = 0.4; Rp-cAMPS, n = 3, NS, p = 0.2; PKI, n = 4, NS, p = 0.1) and parent dendrites (KT5720, n = 4, NS, p = 0.4; Rp-cAMPS, n = 3, NS, p = 0.5; PKI, n = 4, NS, p = 0.4). E, Ratio of the decay times in the presence of salbutamol and PKA inhibitors versus decay times in the presence of PKA inhibitors alone. Both spine Ca2+ transient decay times (KT5720, n = 4, NS, p = 0.18; Rp-cAMPS, n = 3, NS, p = 0.2; PKI, n = 4, NS, p = 0.10) and dendritic decay times (KT5720, n = 4, NS, p = 0.11; Rp-cAMPS, n = 3, NS, p = 0.3; PKI, n = 4, NS, p = 0.16) did not differ significantly from control (only PKA inhibitors).