Activation of rat sympathetic ganglia SIF cell dopamine metabolism by muscarinic agonists.

The biochemical responsiveness of the dopamine-containing small intensely fluorescent (SIF) cells to cholinoceptive drugs was evaluated in rat superior cervical ganglion (SCG), middle-inferior cervical ganglion and celiac ganglion. Amines and metabolites were analyzed by mass fragmentography. The major metabolite of dopamine (DA) in all ganglia was 3,4-dihydroxyphenylacetic acid (DOPAC). Stimulation of muscarinic receptors with carbachol induced a 3-10 fold increase of DOPAC concentration in the ganglia, the celiac ganglion being the most responsive and the SCG being the least. Pretreatment with atropine blocked the rise of DOPAC. The rise of DOPAC after activation of muscarinic receptors was not the consequence of blocking the removal of this acid from the ganglion. We concluded that DA metabolism in SIF cells is enhanced by stimulation of muscarinic receptors and that the magnitude of the DOPAC increase in a ganglion may reflect the importance of DA in ganglionic transmission.