Uptake and release of norepinephrine by slices of rat cerebral cortex: effect of agents that increase cyclic AMP levels.

Cerebral cortical slices from rats were incubated in physiologic saline, and the uptake, release, and K+-stimulated release of norepinephrine were measured. Dibutyryl cyclic AMP, the phosphodiesterase inhibitors aminophylline and papaverine, and adenosine (which stimulates adenyl cyclase) all caused a variable increase in uptake of norepinephrine at concentrations ranging from 10(-7) to 10(-4) M. Prostaglandins E1 and E2 appeared to have no effect on uptake, but this may be because the alcohol required to dissolve them had an inhibitory effect on uptake. None of these compounds appeared to affect basal or K+-stimulated release of norepinephrine. These agents therefore seem to have an effect opposite to that of the tricyclic antidepressants (which inhibit uptake of norepinephrine). Since norepinephrine's postsynaptic effects are usually inhibitory in the cortex, the stimulatory effect of the drugs tested on the presynaptic uptake of norepinephrine may explain the stimulant and epileptogenic effects of these drugs.