Hudetz A G, Smith J J, Lee J G, Bosnjak Z J, Kampine J P
Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, USA.
Am J Physiol. 1995 Jul;269(1 Pt 2):H114-20. doi: 10.1152/ajpheart.1995.269.1.H114.
We investigated whether nitric oxide (NO) played a role in the generation of cerebrocortical flow oscillations and their modification by hypocapnia, hypercapnia, and halothane administration. Parietal cortical laser-Doppler flow (LDF) was monitored transcranially in anesthetized (barbiturate + 0-1.0% halothane), artificially ventilated, adult male Sprague-Dawley rats. Thirty minutes after infusion of N omega-nitro-L-arginine methyl ester (L-NAME, 20 mg/kg i.v.) mean arterial pressure (MAP) increased from 105 +/- 10 to 132 +/- 15 mmHg (P < 0.02), while mean LDF decreased from 159 +/- 36 to 135 +/- 30 perfusion units (PU, P < 0.05). Oscillations in LDF at a frequency of 6.3-7.8 cycles/min and amplitude of 10% were induced or augmented by L-NAME but not by D-NAME or indomethacin (2 mg/kg i.p.). L-arginine (200 mg/kg) abolished the oscillations post-L-NAME at constant MAP. Sodium nitroprusside infusion (10(-5) M, 5-50 microliters/min) reversed the L-NAME-induced increase in MAP and decrease in mean LDF but did not attenuate the flow oscillations. Hypocapnia post-L-NAME decreased LDF to 110 +/- 20 PU (P < 0.001) and augmented the flow oscillations (amplitude: 11-31%). Hypercapnia (5% CO2) or halothane (0.4-1.0%) suspended the oscillations in the presence of L-NAME. The results suggest that NO synthase activity inhibits cerebrocortical flow oscillations, and NO is not an obligatory mediator of the effects of halothane, hypocapnia, and hypercapnia on oscillatory activity.
我们研究了一氧化氮（NO）是否在脑皮质血流振荡的产生以及低碳酸血症、高碳酸血症和氟烷给药对其的调节中发挥作用。在麻醉（巴比妥类药物 + 0 - 1.0%氟烷）、人工通气的成年雄性Sprague-Dawley大鼠中，经颅监测顶叶皮质激光多普勒血流（LDF）。静脉注射Nω-硝基-L-精氨酸甲酯（L-NAME，20 mg/kg）30分钟后，平均动脉压（MAP）从105±10 mmHg升高至132±15 mmHg（P < 0.02），而平均LDF从159±36灌注单位（PU）降至135±30 PU（P < 0.05）。L-NAME可诱导或增强频率为6.3 - 7.8次/分钟、幅度为10%的LDF振荡，但D-NAME或吲哚美辛（2 mg/kg腹腔注射）则不能。在MAP恒定的情况下，L-精氨酸（200 mg/kg）可消除L-NAME注射后的振荡。硝普钠输注（10(-5) M，5 - 50微升/分钟）可逆转L-NAME引起的MAP升高和平均LDF降低，但并未减弱血流振荡。L-NAME注射后的低碳酸血症使LDF降至110±20 PU（P < 0.001）并增强了血流振荡（幅度：11 - 31%）。在存在L-NAME的情况下，高碳酸血症（5% CO2）或氟烷（0.4 - 1.0%）可使振荡停止。结果表明，一氧化氮合酶活性抑制脑皮质血流振荡，并且NO不是氟烷、低碳酸血症和高碳酸血症对振荡活动影响的必需介质。
