Effect of Simultaneous, Transient Calcium and Dopamine Inputs

<div><p>In all panels, the response to dopamine alone is shown with green dashed lines; the response to paired dopamine and calcium is shown with red solid lines.</p><p>(A) The cumulative increase in free PKAc following eight high-amplitude, brief dopamine pulses with 20-s intervals, is enhanced when a high-amplitude, brief calcium input is paired with each dopamine pulse.</p><p>(B) Phosphorylation of Thr34 is enhanced when calcium and dopamine inputs are paired.</p><p>(C) PP1 inhibition is more pronounced when calcium and dopamine inputs are paired due to the increase in phosphoThr34.</p><p>(D) The ratio of PKAc to PP1 is enhanced when calcium and dopamine inputs are paired.</p><p>(E) Some dephosphorylation on Thr75 occurs following a dopamine input due to the PKA dependent activation of PP2A. When in addition calcium is transiently elevated, calcium-dependent activation of PP2A significantly decreases phosphoThr75.</p><p>(F) The total formation of activated PKA (both free and bound to phosphoThr75) is larger with dopamine inputs alone. This is partly due to the calcium-dependent decrease in the cAMP formation, but also the PKAc interaction with phosphoThr75 is important.</p>