Anesthesia and Pain Signal transmission and Role of Ion transporters at Spinal Cord

虽然已经有许多研究证实了局部麻醉剂对Na^+通道、K^+通道和Ca^（2+）通道的作用，但尚不清楚Na^+-K^+ ATP酶（Na泵）、Na^+-H^+交换器、Na^+-K^+-2CL共转运体等离子转运体在麻醉作用和疼痛信号传递中的作用。用培养的PC 12细胞系和脊髓导管动物模型，发现由于蛛网膜下腔注射抑制剂可产生明显的抗伤害作用，Na^+-K^+ ATP酶（Na泵）和Na^+-H^+交换器在脊髓水平的局部麻醉作用中可能起重要作用，而Na^+-K^+-2CL共转运体则不起作用。Oubabain和amiloride似乎不影响信号分子如丝裂原活化蛋白激酶（MAPK）家族成员、细胞外信号调节激酶（ERK）、PKC和PLC，而局麻药影响这些信号分子。局麻药丁卡因通过磷酸化MAPK家族诱导PC 12细胞凋亡ERK的激活保护细胞免于死亡，而JNK则起相反的作用。丁卡因引起的毒性Ca^<2+>内流似乎是凋亡细胞死亡的原因，但Na^+通道和L型Ca^<2+>通道的阻断不太可能参与丁卡因对凋亡信号分子的作用。

Although there have been many studies in which local anesthetic action has been examined on Na^+ channels and K^+ channels and Ca^(2+) channels, it has not been known as to roles of ion transporters such as Na^+-K^+ATPase ( Na pump ), Na^+-H^+ exchanger, Na^+-K^+-2CL cotranspoter on anesthetic action as well as pain signal transmission. Using cultured cell lines of PC12 cells and animal model with spinal catheter, we found that since their inhibitors administered into spinal subarachinoid caused significant antinociceptive action, Na^+-K^+ATPase ( Na pump ) and Na^+-H^+ exchanger would have significantrole in local anestheticaction at the spinal cord level, but not with Na^+-K^+-2CL cotranspoter. Oubabain and amiloride seem not to affect signaling molecules such as mitogen-activated protein kinase ( MAPK ) family members, extracellularsignal-regulatedkinases ( ERKs ), PKC, and PLC.On the other hand, local anesthetics affect such signaling molecules. Local anesthetic tetracaine induces apoptosis of PC12 cells via phosphorylation of MAPK family. ERK activation protects cells from death, but JNK plays the opposite role. Toxic Ca^<2+> influx caused by tetracaine seems to be responsible for apoptoticcell death, but blocking of Na^+ channels and L-type Ca^<2+> channels is unlikely involved in such tetracaine'saction on signaling molecules for apoptosis.