Kuboki J, Ishiguro S, Tamai M
Department of Ophthalmology, Tohoku University School of Medicine, Sendai, Japan.
Tohoku J Exp Med. 1999 Apr;187(4):353-61. doi: 10.1620/tjem.187.353.
It is possible that Na, K-ATPase may play some roles in ischemic damage of nervous tissue. To determine whether Na, K-ATPase is affected in ischemic and reperfused retina, we measured enzyme activities. Retinal ischemia was induced by clamping the optic nerve of female adult Sprague-Dawley (SD) rats for 90 minutes. At 0.5, 2 and 24 hours after reperfusion, rat eyes were enucleated, and the retinas were removed. In addition to unseparated, total ouabain-sensitive Na, K-ATPase activity, we measured weakly ouabain-sensitive (alpha) and highly ouabain-sensitive (alpha[+]) isoform activities separately by ATP hydrolysis. Total ouabain-sensitive Na, K-ATPase activity, alpha and alpha(+) isoform activities showed no significant difference from sham-operated contralateral eyes at 0.5 and 2 hours of reperfusion. After 24 hours of reperfusion, total ouabain-sensitive Na, K-ATPase activity decreased to 63% of the control. The activities of alpha and alpha(+) isoforms were 47% and 72%, respectively. The ratios of the alpha and alpha(+) isoform activities (alpha/alpha[+]) significantly decreased at 2 and 24 hours of reperfusion. Activity in a isoform decreased markedly in reperfused rat retinas. This response may be beneficial for reducting the oxidative stress in reperfused retinas.
钠钾ATP酶可能在神经组织的缺血性损伤中发挥某些作用。为了确定钠钾ATP酶在缺血再灌注视网膜中是否受到影响，我们测量了酶活性。通过夹闭成年雌性Sprague-Dawley（SD）大鼠的视神经90分钟来诱导视网膜缺血。在再灌注后0.5、2和24小时，摘除大鼠眼球并取出视网膜。除了未分离的、总的哇巴因敏感钠钾ATP酶活性外，我们还通过ATP水解分别测量了弱哇巴因敏感（α）和高哇巴因敏感（α[+]）同工型活性。在再灌注0.5和2小时时，总的哇巴因敏感钠钾ATP酶活性、α和α（+）同工型活性与假手术对侧眼相比无显著差异。再灌注24小时后，总的哇巴因敏感钠钾ATP酶活性降至对照的63%。α和α（+）同工型活性分别为47%和72%。在再灌注2和24小时时，α和α（+）同工型活性的比率（α/α[+]）显著降低。再灌注大鼠视网膜中α同工型的活性明显降低。这种反应可能有利于减轻再灌注视网膜中的氧化应激。
