Abstract
Noradrenaline (NA) can be released by both exocytosis and by the membrane transporter responsible for transmitter uptake. Previously, we reported that S-nitrosocysteine (SNC), an S-nitrosothiol, stimulated [ 3H]NA release from the rat hippocampus. In this study, we investigated the involvement of the NA transport system in SNC-stimulated NA release from rat brain (cerebral cortex and hippocampus) slices. [ 3H]NA release by SNC in normal Na + (148 mM)-containing buffer from both slices was slightly, but significantly, inhibited by 1 μM desipramine, an NA transporter inhibitor. [ 3H]NA release in low Na + (under 14 mM)-containing buffer was inhibited by over 50% by desipramine. [ 3H]NA release by tyramine from both slices in normal and low Na + buffer was almost completely inhibited by desipramine. [ 3H]NA uptake into cerebral cortical slices was observed in low Na + buffer at 20–30% of normal Na + buffer levels. [ 3H]NA uptake in both normal and low Na + buffers was inhibited by desipramine and by SNC. Although [ 3H]NA uptake in normal Na + buffer was almost completely inhibited by 500 μM ouabain, the uptake in low Na + buffer was resistant to ouabain. These findings suggest the existence of a functional Na +-independent NA transport system and that SNC stimulates NA release at least partially via this system in brain slices.
Published Version
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