Kitayama J, Kitazono T, Ibayashi S, Wakisaka M, Watanabe Y, Kamouchi M, Nagao T, Fujishima M
Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
Stroke. 2000 Oct;31(10):2487-93. doi: 10.1161/01.str.31.10.2487.
We tested the hypothesis that activation of phosphatidylinositol (PI) 3-kinase is involved in dilator responses of the basilar artery to acetylcholine in vivo.
Responses of the basilar artery were measured by the cranial window technique in anesthetized rats. To examine the role of PI 3-kinase in acetylcholine-induced calcium signaling, we measured intracellular free calcium concentration (Ca(2+)) of cultured rat basilar arterial endothelial cells using a fluorescent calcium indicator, indo 1.
-Topical application of acetylcholine (10(-6), 10(-5.5), and 10(-5) mol/L) increased the diameter of the basilar artery by 8+/-1%, 14+/-2%, and 24+/-3%, respectively. An inhibitor of PI 3-kinase, wortmannin (10(-8) mol/L), did not change the baseline diameter of the artery. In the presence of wortmannin, acetylcholine (10(-6), 10(-5.5), and 10(-5) mol/L) dilated the artery only by 3+/-2%, 6+/-2%, and 12+/-2%, respectively. Thus, wortmannin attenuated acetylcholine-induced dilatation of the basilar artery (P<0.05 versus control). Wortmannin had no effect on dilatation of the artery in response to a nitric oxide donor, sodium nitroprusside. LY294002, another inhibitor of PI 3-kinase, also inhibited dilator response of the basilar artery to acetylcholine. Acetylcholine produced an increase in Ca(2+) of the endothelial cells. Genistein, an inhibitor of tyrosine kinase, markedly attenuated acetylcholine-induced calcium influx to the cells; however, wortmannin had no effect on acetylcholine-induced calcium changes.
These results suggest that acetylcholine-induced dilatation of the basilar artery is mediated, at least in part, by activation of PI 3-kinase in vivo. Acetylcholine-induced Ca(2+) changes of the endothelial cells may not be mediated by activation of the kinase. PI 3-kinase as well as Ca(2+) may play an important role in the acetylcholine-induced nitric oxide production of the basilar arterial endothelial cells.
我们验证了磷脂酰肌醇（PI）3激酶的激活参与体内基底动脉对乙酰胆碱舒张反应的假说。
在麻醉大鼠中采用颅窗技术测量基底动脉的反应。为研究PI 3激酶在乙酰胆碱诱导的钙信号传导中的作用，我们使用荧光钙指示剂indo 1测量培养的大鼠基底动脉内皮细胞的细胞内游离钙浓度（[Ca(2+)]i）。
局部应用乙酰胆碱（10(-6)、10(-5.5)和10(-5) mol/L）使基底动脉直径分别增加8±1%、14±2%和24±3%。PI 3激酶抑制剂渥曼青霉素（10(-8) mol/L）未改变动脉的基础直径。在渥曼青霉素存在的情况下，乙酰胆碱（10(-6)、10(-5.5)和10(-5) mol/L）仅使动脉分别扩张3±2%、6±2%和12±2%。因此，渥曼青霉素减弱了乙酰胆碱诱导的基底动脉扩张（与对照组相比，P<0.05）。渥曼青霉素对动脉对一氧化氮供体硝普钠的扩张无影响。另一种PI 3激酶抑制剂LY294002也抑制基底动脉对乙酰胆碱的舒张反应。乙酰胆碱使内皮细胞的[Ca(2+)]i增加。酪氨酸激酶抑制剂染料木黄酮显著减弱乙酰胆碱诱导的细胞钙内流；然而，渥曼青霉素对乙酰胆碱诱导的钙变化无影响。
这些结果表明，乙酰胆碱诱导的基底动脉扩张至少部分是由体内PI 3激酶的激活介导的。乙酰胆碱诱导的内皮细胞[Ca(2+)]i变化可能不是由该激酶的激活介导的。PI 3激酶以及[Ca(2+)]i可能在乙酰胆碱诱导的基底动脉内皮细胞一氧化氮生成中起重要作用。
