Mechanisms of non-quantal amino acid release by nitric oxide

研究了P物质和一氧化氮（NO）及其相关物质对新生大鼠脊髓制剂中氨基酸释放的作用机制，并探讨了氨基酸转运体参与释放的可能性。P物质（10 μM）灌注脊髓可诱导谷氨酸、天冬氨酸、GABA、甘氨酸和牛磺酸的释放。NO供体SNAP （300 μM）和SIN-1 （300 μM）也以类似的方式释放这些氨基酸。P物质诱导的氨基酸释放在无钙培养基中无明显变化。然而，灌注低钠培养基显著减少氨基酸释放。灌注低cl培养基可减少GABA、甘氨酸和牛磺酸的释放。p物质诱发的GABA释放也被GABA转运蛋白抑制剂抑制。在一氧化氮供体引起的氨基酸释放中也发现了类似的结果。上述结果提示，P物质和NO及其供体可引起新生大鼠脊髓中氨基酸的释放，氨基酸转运体的逆转操作参与了释放机制。

The mechanisms of actions of substance P and nitric oxide (NO) and associated substances on the release of amino acids from neonatal rat spinal cord preparations were examined and the possibility of involvement of amino acid transporters in the release was explored.Application of substance P (10 μM) by perfusion to the spinal cord induced a release of glutamate, aspartate, GABA, glycine and taurine. The NO donor, SNAP (300 μM) and SIN-1 (300 μM) also released these amino acids in a similar manner. The amino acid release evoked by substance P did not change in the presence of calcium-free medium. However, perfusion of a low-Na medium significantly reduced the amino acid release. The release of GABA, glycine and taurine was reduced by perfusion of a low-Cl medium. The substance P-evoked release of GABA was also suppressed by an inhibitor of GABA transporter. Similar findings were found in the amino acid release evoked by the NO donors.These results suggest that substance P as well as NO and its donors evoke a release of amino acids from the neonatal rat spinal cord and reversal operation of transporters of amino acids is involved in the mechanism of release.