Pei L, Li Y, Yan J Z, Zhang G Y, Cui Z C, Zhu Z M
Research Center of Biochemistry and Molecular Biology, Xuzhou Medical College, Xuzhou 221002, China.
Acta Pharmacol Sin. 2000 Aug;21(8):715-20.
To study the changes and mechanisms of protein-tyrosine kinase (PTK) and protein-tyrosine phosphatase (PTP) activities in the hippocamal synaptosome following cerebral ischemia/reperfusion (I/R) in gerbil.
Transient (15 min) global ischemia was produced by bilateral carotid artery occlusion. Total PTK and PTP activities were measured by [r-32P] incorporation and colorimetric analysis, respectively. Src and proline-rich tyrosine kinase2 (PYK2) activities were measured by immunoprecipitation and [r-32P] incorporation.
Total PTK activity increased significantly after I/R, but the PTP activity did not change. The Src activity was much higher than PYK2 activity in sham-operated controls. I/R mainly caused a pronounced increase in Src activity, but not PYK2 activity. The increase in Src activity had no relation to the expression of Src protein. Administration of ketamine (KT) or nifedipine (ND) 20 min before ischemia caused a decrease in total PTK and Src activities, and no change in the PYK2 and PTP activities.
The increase in PTK activity caused by I/R may be mainly due to the increase in Src activity. This increase in Src activity has no relation to the expression of Src protein. But it is related to the activation of NMDA (N-methyl-D-aspartate) receptor (NR) and L-type voltage-gated calcium channel (L-type VGCC). In other words, the increase in total PTK and Src activities induced by I/R may be mediated via NR and L-type VGCC. The PTP activity did not change during I/R.
研究沙土鼠脑缺血/再灌注（I/R）后海马突触体中蛋白酪氨酸激酶（PTK）和蛋白酪氨酸磷酸酶（PTP）活性的变化及其机制。
通过双侧颈总动脉闭塞造成短暂性（15分钟）全脑缺血。分别采用[r-32P]掺入法和比色分析法测定总PTK和PTP活性。通过免疫沉淀和[r-32P]掺入法测定Src和富含脯氨酸的酪氨酸激酶2（PYK2）活性。
I/R后总PTK活性显著增加，但PTP活性未改变。在假手术对照组中，Src活性远高于PYK2活性。I/R主要导致Src活性显著增加，而PYK2活性未增加。Src活性的增加与Src蛋白的表达无关。缺血前20分钟给予氯胺酮（KT）或硝苯地平（ND）可使总PTK和Src活性降低，而PYK2和PTP活性无变化。
I/R引起的PTK活性增加可能主要归因于Src活性的增加。这种Src活性的增加与Src蛋白的表达无关，但与N-甲基-D-天冬氨酸（NMDA）受体（NR）和L型电压门控钙通道（L型VGCC）的激活有关。换句话说，I/R诱导的总PTK和Src活性增加可能是通过NR和L型VGCC介导的。I/R期间PTP活性未改变。
