I am struggling in finding information in literature what the concentration ranges are for dopamine in PC12 cells - often it is contradictory and varies a lot depending on the pretreatment (naturally). I am interested to know what is the "standard" concentration range of intracellular (NOT intravesicular) dopamine and the "standard" concentration range for their exocytotic release of dopamine. I don't need exact numbers, just range estimates. 

The PC12 are assumed to have been supplemented by Ca2+, K+, glucose, and calf serum, so no loading with L-DOPA or similar stuff.