Inhibition of Nitric Oxide Synthesis Increases Focal Ischemic Infarction in Rat

Journal of Cerebral Blood Flow & Metabolism, Год журнала: 1992, Номер 12(5), С. 717 - 726

Опубликована: Сен. 1, 1992

We investigated whether inhibition of nitric oxide (NO) biosynthesis with N-ω-nitro-l-arginine (NNA), a competitive inhibitor NO synthase (NOS), would modify the volume focal ischemic infarction produced by occlusion middle cerebral artery (MCA) in spontaneously hypertensive rats. NNA was infused for 1 h (2.4 mg/kg/h) immediately following MCA. increased lesion 24 later 32% over controls (150.8 ± 16.6 to 199.2 17.4 mm 3 ; p < 0.001, n = 6). This effect antagonized co-infusion l- but not d-arginine. The antihypertensive rilmenidine (0.75 mg/kg) reduced 27% (p 0.05, 4). Changes size were confined penumbra. arterial pressure (AP) (118 8.9 149 16.0 Hg; 0.01, 3) did change regional CBF. However, elevation AP or distribution. conclude that constitutive form NOS vivo increases as consequence biosynthesis. absence availability may extend formation reactive hyperemia, platelet disaggregation, and/or release neuroprotective neuromodulators penumbra, which counteract and override any its neurotoxic actions.

Язык: Английский

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Continuous monitoring of regional cerebral blood flow: experimental and clinical validation of a novel thermal diffusion microprobe

Journal of neurosurgery, Год журнала: 2000, Номер 93(2), С. 265 - 274

Опубликована: Авг. 1, 2000

Object. Current clinical neuromonitoring techniques lack adequate surveillance of cerebral perfusion. In this article, a novel thermal diffusion (TD) microprobe is evaluated for the continuous and quantitative assessment intraparenchymal regional blood flow (rCBF). Methods. To characterize temporal resolution new technique, rCBF measured using TD (TD-rCBF) was compared with levels by laser Doppler (LD) flowmetry during standardized variations CBF in sheep model. For validation absolute values, implanted subcortically (20 mm below level dura) into 16 brain-injured patients, TD-rCBF simultaneous measurements obtained stable xenon-enhanced computerized tomography scanning (sXe-rCBF). The two were linear regression analysis as well Bland Altman method. Stable could be throughout all 3- to 5-hour experiments. During hypercapnia, increased from 49.3 ± 15.8 ml/100 g/min (mean standard deviation) 119.6 47.3 g/min, whereas hypocapnia produced decline 51.2 12.8 39.3 5.6 g/min. Variations mean arterial pressure revealed an intact autoregulation limits approximately 65 Hg 170 Hg. After cardiac arrest declined rapidly 0 dynamics changes corresponded LD readings. A comparison sXe-rCBF good correlation (r = 0.89; p <0.0001) difference 1.1 5.2 between techniques. Conclusions. provides sensitive, continuous, real-time values that are agreement measurements. This study basis integration multimodal monitoring patients who at risk secondary brain injury.

Язык: Английский

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Role of nitric oxide in the coupling of cerebral blood flow to neuronal activation in rats

Neuroscience Letters, Год журнала: 1993, Номер 149(1), С. 43 - 46

Опубликована: Янв. 1, 1993

Язык: Английский

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Changes in Amino Acid Neurotransmitters and Cerebral Blood Flow in the Ischemic Penumbral Region following Middle Cerebral Artery Occlusion in the Rat: Correlation with Histopathology

Journal of Cerebral Blood Flow & Metabolism, Год журнала: 1993, Номер 13(4), С. 575 - 585

Опубликована: Июль 1, 1993

We simultaneously measured neurotransmitter amino acids by the microdialysis technique and cortical CBF laser-Doppler flowmetry in ischemic penumbral cortex of rats subjected to 2-h normothermic (36.5–37.5°C) transient middle cerebral artery (MCA) clipocclusion. Brains were perfusion-fixed 3 days later infarct volume measured. (% preischemic values) fell 32 ± 2% (mean SD) during ischemia rose 157 68% recirculation. Extracellular glutamate levels increased from a baseline value 7 μ M peak 180 247 20–30 min following onset but subsequently returned near after 70 despite ongoing MCA occlusion. The threshold for moderate release was 48%. Massive seen first 60 occlusion two animals showing largest infarcts occurred at values ≤20% control levels. Mean exhibited an inverse relationship with volume, magnitude positively correlated volume. γ-aminobutyrate glycine changes similar those showed no significant correlation These results suggest that (a) accumulation extracellular is important determinant injury setting reversible (b) reuptake systems may be functional penumbra focal ischemia. have shown temporary occlusion, acid initially rise decline massive GABA occur It suggested might require lower 20%. size resultant infarct. are consistent impressions previous investigations implicated glutamatergic mechanisms injury. well known MK-801 other glutamate-related receptor antagonists effective reducing models (Ozyurt et al., 1988; Park 1988 b; Simon Shiraishi, 1990; Buchan 1991; Smith Meldrum, 1992). While contributory factor, it nonetheless unlikely sole cause infarction ischemia, as nonneuronal events also participate formation (Plum, 1983; Dietrich Globus 1991).

Язык: Английский

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A Review of Brain Retraction and Recommendations for Minimizing Intraoperative Brain Injury

Neurosurgery, Год журнала: 1993, Номер 33(6), С. 1052 - 1064

Опубликована: Дек. 1, 1993

BRAIN RETRACTION IS required for adequate exposure during many intracranial procedures. The incidence of contusion or infarction from overzealous brain retraction is probably 10% in cranial base procedures and 5% aneurysm literature on injury reviewed, with particular attention to the use intermittent retraction. Intraoperative monitoring techniques–brain electrical activity, cerebral blood flow, pressure–are evaluated. Various intraoperative interventions–anesthetic agents, positioning, cerebrospinal fluid drainage, operative approaches involving bone resection osteotomy, hyperventilation, induced hypotension, hypertension, mannitol, nimodipine–are assessed regard their effects Because injury, like other forms focal ischemia, multifactorial its origins, a multifaceted approach will be most advantageous minimizing injury. Recommendations management cases significant are made. These recommendations optimize following goals: anesthesia metabolic depression, improvement flow calcium channel blockade, monitoring, efficacy. Through combination judicious retraction, appropriate anesthetic pharmacological management, aggressive should become much less common source morbidity future.

Язык: Английский

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