脑缺血再灌注后酪氨酸蛋白激酶和蛋白磷酸酶的活性变化及其机制(英文)

目的:研究脑缺血再灌注后沙土鼠海马突触体蛋白质酪氨酸激酶(PTK)和蛋白质酪氨酸磷酸酶(PTP)活性的变化及其引起变化的机制。方法:双侧颈总动脉结扎(15min)形成全脑缺血模型;放射性同位素γ-~(32)P掺入法和比色法分别测定了总PTK和PTP的活性,免疫沉淀和γ-~(32)P放射性同位素测定Src和PYK_2活性,免疫印渍测定Src和PYK_2蛋白表达量。结果:①脑缺血再灌注引起PTK活性升高,而PTP活性不变。②在假手术对照组中,Src比PYK_2活性高,脑缺血再灌引起Src活性明显升高,而PYK_2活性无显著变化。③脑缺血前腹腔分别给予氯胺酮和硝苯地平,都能拮抗脑缺血再灌注引起的PTK和Src活性的升高,但对PTP活性无影响。结论:脑缺血再灌注能诱导沙土鼠海马突触体总的PTK活性升高,而对PTP活性无影响,PTK活性的升高主要是Src活性的增加而与PYK_2无关;脑缺血再灌注诱导PTK和Src活性升高是通过NR和L-型电压门控钙通道介导的,即与这两种钙通道的激活有关,而与其蛋白表达量无关。

Changes and mechanisms of protein-tyrosine kinase and protein-tyrosine phosphatase activities after brain ischemia/reperfusion~1

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.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. METHODS: Transient (15 min) global ischemia was produced by bilateral carotid artery occlusion. Total PTK and PTP activities were measured by [r-32p] incorporation and col-orimetric analysis, respectively. Src and proline-rich tyrosine kinase2 (PYK2) activities were measured by im-munoprecipitation and [r-32p] incorporation. RESULTS: 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. CONCLUSION; 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