Compartmentalization of @entity1919 elevation in neurons of XXXX .

@entity268 @entity1920 @entity1372 @entity1919 @entity11066 @entity1760
We have measured by radioimmunoassay the amount of total, free, and bound forms of @entity1919 ( @entity268 ) within the abdominal ganglion and in five identified cell bodies of neurons from @entity11066 . In the abdominal ganglion the unbound (free) @entity268 levels comprised approximately 25-30% of the total @entity268 content under the unstimulated condition, i.e., bathed in high- @entity1760 saline. Under pharmacological conditions that blocked endogenous phosphodiesterase and activated @entity1920 cyclase, ganglionic free @entity268 levels were elevated more than fourfold, while bound @entity268 levels more than doubled. Freeze-substitution techniques were employed to facilitate isolation of individual cell bodies either before or after pharmacological manipulation of @entity268 levels. The basal, free @entity268 content of cells R2, LP1, R15, L11, and L2-L6 was in the range of 10-40 pmol/mg of cell protein, which accounted for approximately one-half of the total @entity268 content per cell body. Determinations of individual cell volumes indicated that the basal, free @entity268 concentrations ranged from 1 to 6 microM. Under the same pharmacological conditions that elevated ganglionic @entity268 in levels, no changes were measured in either the free or the bound forms of @entity268 in isolated cell bodies. Our results indicate that the @entity268 elevation was compartmentalized within the neuropilar region of the ganglion, most likely within the processes of the nerve cells. Previous results demonstrated that @entity268 injections into the same Aplysia neurons studied here induced a @entity268 -activated @entity1372 current, INa ( @entity268 ). In this report we discuss the possibility that pharmacological elevation of @entity268 within neuronal processes may reach concentrations similar to those produced by @entity268 injections into somata.
