Faraci F M, Heistad D D
Department of Internal Medicine, University of Iowa College of Medicine, Iowa City 52242.
Brain Res. 1994 Aug 22;654(2):349-51. doi: 10.1016/0006-8993(94)90499-5.
The first goal of this study was to examine the hypothesis that aging impairs dilator responses of cerebral arterioles to N-methyl-D-aspartate (NMDA). The second goal was to determine whether aging impairs vasodilatation in response to activation of ATP-sensitive K+ channels. Diameter of cerebral arterioles was measured through a cranial window in anesthetized adult (5 +/- 1 (mean +/- S.E.) months old) and old (26 +/- 1 months old) Fischer 344 rats. In adult rats, NMDA (10 and 100 microM) dilated pial arterioles by 14 +/- 5 and 72 +/- 9%, respectively, from a control diameter of 36 +/- 5 microns. Aprikalim (1 and 10 microM), a direct activator of ATP-sensitive potassium channels, dilated cerebral arterioles in adult rats by 14 +/- 3 and 49 +/- 6%, respectively. Vasodilatation in response to NMDA and aprikalim were similar in old and adult rats. Thus, in contrast to impaired cerebral vasodilator responses to some stimuli, responses of cerebral arterioles to NMDA and activation of ATP-sensitive potassium channels are preserved in old Fischer 344 rats.
本研究的首要目标是检验衰老会损害脑微动脉对N-甲基-D-天冬氨酸（NMDA）的舒张反应这一假说。第二个目标是确定衰老是否会损害因ATP敏感性钾通道激活而产生的血管舒张作用。通过颅骨视窗测量麻醉的成年（5±1（均值±标准误）月龄）和老年（26±1月龄）Fischer 344大鼠脑微动脉的直径。在成年大鼠中，NMDA（10和100微摩尔）使软脑膜动脉分别从36±5微米的对照直径扩张了14±5%和72±9%。阿普卡林（1和10微摩尔），一种ATP敏感性钾通道的直接激活剂，使成年大鼠的脑微动脉分别扩张了14±3%和49±6%。老年和成年大鼠对NMDA和阿普卡林的血管舒张反应相似。因此，与脑对某些刺激的血管舒张反应受损不同，老年Fischer 344大鼠脑微动脉对NMDA和ATP敏感性钾通道激活的反应得以保留。
