sodium-nitrite and Brain-Ischemia

Subarachnoid haemorrhage (SAH) is associated with long-term disability, serious reduction in quality of life and significant mortality. Early brain injury (EBI) refers to the pathological changes in cerebral metabolism and blood flow that happen in the first few days after ictus and may lead on to delayed cerebral ischaemia (DCI). A disruption of the nitric oxide (NO) pathway is hypothesised as a key mechanism underlying EBI. A decrease in the alpha-delta power ratio (ADR) of the electroencephalogram has been related to cerebral ischaemia. In an experimental medicine study, we tested the hypothesis that intravenous sodium nitrite, an NO donor, would lead to increases in ADR. We studied 33 patients with acute aneurysmal SAH in the EBI phase. Participants were randomised to either sodium nitrite or saline infusion for 1 h. EEG measurements were taken before the start of and during the infusion. Twenty-eight patients did not develop DCI and five patients developed DCI. In the patients who did not develop DCI, we found an increase in ADR during sodium nitrite versus saline infusion. In the five patients who developed DCI, we did not observe a consistent pattern of ADR changes. We suggest that ADR power changes in response to nitrite infusion reflect a NO-mediated reduction in cerebral ischaemia and increase in perfusion, adding further evidence to the role of the NO pathway in EBI after SAH. Our findings provide the basis for future clinical trials employing NO donors after SAH.

Topics: Biomarkers; Brain Injuries; Brain Ischemia; Cerebral Infarction; Electroencephalography; Humans; Quality of Life; Sodium Nitrite; Subarachnoid Hemorrhage

Cardiac arrest results in significant mortality after initial resuscitation due in most cases to ischemia-reperfusion induced brain injury and to a lesser degree myocardial dysfunction. Nitrite has previously been shown to protect against reperfusion injury in animal models of focal cerebral and heart ischemia. Nitrite therapy after murine cardiac arrest improved 22 h survival through improvements in myocardial contractility. These improvements accompanied transient mitochondrial inhibition which reduced oxidative injury to the heart. Based on preliminary evidence that nitrite may also protect against ischemic brain injury, we sought to test this hypothesis in a rat model of asphyxia cardiac arrest with prolonged survival (7d). Cardiac arrest resulted in hippocampal CA1 delayed neuronal death well characterized in this and other cardiac arrest models. Nitrite therapy did not alter post-arrest hemodynamics but did result in significant (75%) increases in CA1 neuron survival. This was associated with increases in hippocampal nitrite and S-nitrosothiol levels but not cGMP shortly after therapy. Mitochondrial function 1h after resuscitation trended towards improvement with nitrite therapy. Based on promising preclinical data, the first ever phase I trial of nitrite infusions in human cardiac arrest survivors has been undertaken. We present preliminary data showing low dose nitrite infusion did not result in hypotension or cause methemoglobinemia. Nitrite thus appears safe and effective for clinical translation as a promising therapy against cardiac arrest mediated heart and brain injury.

Topics: Animals; Blood Pressure; Brain Ischemia; CA1 Region, Hippocampal; Cyclic GMP; Double-Blind Method; Heart Arrest; Heart Rate; Humans; Male; Methemoglobin; Mitochondria; Neuroprotective Agents; Random Allocation; Rats; Rats, Sprague-Dawley; S-Nitrosothiols; Sodium Nitrite

Brain ischaemic hypoxia can produce severe neurological damage that leads to behavioural disorders. This research analysed the hippocampal and cerebellar histological alterations caused by brain ischaemic hypoxia experimentally induced by sodium nitrite (NaNO. An experimental study was carried out by administering 60mg/kg NaNO. The number of neurons with lesions was significantly higher in animals exposed to NaNO. NaNO

Topics: Animals; Anxiety; Blood Glucose; Brain Ischemia; Cerebellum; Cholesterol; Depression; Hippocampus; Hydrocortisone; Hypoxia, Brain; Lactic Acid; Motor Activity; Neurons; Rats, Wistar; Sodium Nitrite

Aneurysmal subarachnoid hemorrhage often leads to death and poor clinical outcome. Injury occurring during the first 72 hours is termed "early brain injury," with disruption of the nitric oxide pathway playing an important pathophysiologic role in its development. Quantitative electroencephalographic variables, such as α/δ frequency ratio, are surrogate markers of cerebral ischemia. This study assessed the quantitative electroencephalographic response to a cerebral nitric oxide donor (intravenous sodium nitrite) to explore whether this correlates with the eventual development of delayed cerebral ischemia.. Unblinded pilot study testing response to drug intervention.. Neuroscience ICU, John Radcliffe Hospital, Oxford, United Kingdom.. Fourteen World Federation of Neurosurgeons grades 3, 4, and 5 patients (mean age, 52.8 yr [range, 41-69 yr]; 11 women).. IV sodium nitrite (10 μg/kg/min) for 1 hour.. Continuous electroencephalographic recording for 2 hours. The alpha/delta frequency ratio was measured before and during IV sodium nitrite infusion. Seven of 14 patients developed delayed cerebral ischemia. There was a +30% to +118% (range) increase in the alpha/delta frequency ratio in patients who did not develop delayed cerebral ischemia (p < 0.0001) but an overall decrease in the alpha/delta frequency ratio in those patients who did develop delayed cerebral ischemia (range, +11% to -31%) (p = 0.006, multivariate analysis accounting for major confounds).. Administration of sodium nitrite after severe subarachnoid hemorrhage differentially influences quantitative electroencephalographic variables depending on the patient's susceptibility to development of delayed cerebral ischemia. With further validation in a larger sample size, this response may be developed as a tool for risk stratification after aneurysmal subarachnoid hemorrhage.

Topics: Adult; Aged; Aneurysm, Ruptured; Brain Ischemia; Electroencephalography; Female; Humans; Infusions, Intravenous; Intensive Care Units; Intracranial Aneurysm; Male; Middle Aged; Nitric Oxide Donors; Pilot Projects; Sodium Nitrite; Subarachnoid Hemorrhage

Nitrite-derived NO protects against middle cerebral artery occlusion in mice. We developed a new mouse model of global cerebral ischemia and reperfusion (GCI/R) involving reversible occlusion of the major vessels from the aortic arch supplying the brain, and investigated neuroprotection with dietary sodium nitrite supplementation against GCI/R injury.. Mice received drinking water with (nitrite group) or without (control group) sodium nitrite (2 mM) for 5 days and underwent 3-min GCI/R by reversible occlusion of major vessels from the aortic arch (i.e., brachiocephalic, left common carotid, and left subclavian artery). Survival rates and neurological function scores were evaluated for up to 5 days after GCI/R. Histopathological studies were performed to detect neurological degeneration and caspase-3 activation in serial hippocampal sections.. In the control group, 17/30 mice (57 %) survived 5 days after 3-min GCI/R, whereas in the nitrite group 25/30 mice (83 %) survived (p < 0.05). The neurological score at 5 days after GCI in control group was significantly higher than in the nitrite group. Cerebral blood flow (CBF) during GCI was significantly higher in the nitrite group than in the control group, while MABP did not differ significantly between groups. Degenerative changes and caspase-3 activation in hippocampal sections after GCI were observed in the control group but not in the nitrite group. Pretreatment with the NO scavenger c-PTIO abolished the neuroprotective effects of sodium nitrite.. Sodium nitrite supplementation attenuated mortality and neurological impairment after 3-min GCI in mice; an effect likely mediated via vascular mechanisms involving NO.

Topics: Animals; Brain; Brain Ischemia; Caspase 3; Cerebrovascular Circulation; Dietary Supplements; Disease Models, Animal; Hippocampus; Male; Mice; Mice, Inbred C57BL; Neuroprotective Agents; Reperfusion Injury; Sodium Nitrite

A water-soluble polysaccharide, named as SNP, was extracted and fractioned from the body wall of Sipunculus nudus L. by DEAE-Sepharose anion exchange and Sepharose CL-6B column chromatography. The evaluation for anti-hypoxia activity demonstrated that SNP had significant anti-hypoxic activity on normobarie hypoxia, chemical intoxicant hypoxia and acute cerebral ischemia hypoxia models in mice. SNP also enhanced the number of red blood cell count (RBC) and the concentration of hemoglobin (HGB). The structural characteristics of SNP investigated by high performance size exclusion chromatography, Fourier transform infrared spectroscopy and gas chromatography-mass spectrometry indicated that SNP was a homogeneous polysaccharide with a molecular mass of 350 kD and was composed of rhamnose (28%), fucose (16%) and galactose (56%). The results suggested that SNP could be explored as a novel potential anti-hypoxia agent.

Topics: Animals; Annelida; Brain Ischemia; Hypoxia; Methylation; Mice; Polysaccharides; Sodium Nitrite; Spectrophotometry, Infrared; Survival Analysis; Toxicity Tests

Crude water-soluble polysaccharides (BRP) were extracted from the root of Brassica rapa L. using boiling-water. The polysaccharides were successively purified by chromatography on DEAE-cellulose and Sephadex G-100 column, giving three major polysaccharide fractions termed BRP1-1, BRP2-1, BRP3-1. The gel permeation chromatography (GPC) analysis showed that the average molecular weight (Mw) of polysaccharides (BRP1-1, BRP2-1, BRP3-1) were approximately 5.53×10(3) Da, 3.35×10(4) Da and 3.37×10(4) Da, respectively. Monosaccharide components analysis indicated that BRP1-1 was composed of arabinose and glucose in a molar ratio of 1.66:98.34. BRP2-1 was composed of arabinose, galactose and glucose in a molar ratio of 9.3:14.63:76.07. BRP3-1 was composed of arabinose, rhamnose, galactose and glucose in a molar ratio of 24.98:24.10:44.09:6.83. The evaluation of anti-hypoxia activity in vivo revealed that BRP is a novel potential anti-hypoxia agent.

Topics: Acute Disease; Animals; Brain Ischemia; Brassica rapa; Chemical Fractionation; Chromatography; Erythrocyte Count; Hemodynamics; Hemoglobins; Hypoxia; Male; Mice; Molecular Weight; Monosaccharides; Polysaccharides; Sodium Nitrite; Spectroscopy, Fourier Transform Infrared; Survival Analysis; Time Factors; Toxicity Tests

Our recent work suggested that early infusion of nitrite might represent a novel therapeutic approach for acute ischemic stroke. In this study, we sought to examine the therapeutic time window of nitrite in an experimental stroke model, and to develop combined strategies for augmenting its protective effects. Nitrite was infused at various times after ischemia to rats subjected to transient or permanent focal ischemia. Nitrite was infused with memantine to prevent the potential toxicity. Infarct volumes, functional outcomes, microhypoxic areas, and oxidative stress were measured. Nitrite reduced the infarction volume and enhanced functional recovery when administered within 3 and 1.5h in the transient and permanent model, respectively. Combined therapy with nitrite and memantine prolonged the time window up to 4.5h. The potential oxidative toxicities of nitrite were significantly inhibited by memantine. The combination therapy of nitrite and memantine may be a feasible therapeutic approach for acute ischemic stroke.

Topics: Animals; Brain Ischemia; Disease Models, Animal; Drug Therapy, Combination; Excitatory Amino Acid Antagonists; Male; Memantine; Neuroprotective Agents; Oxidative Stress; Rats; Rats, Sprague-Dawley; Receptors, N-Methyl-D-Aspartate; Sodium Nitrite; Stroke

The measurement of the total level of nitric oxide (NO) metabolite (NO(x)(-)) by microdialysis has recently been used to assess the production of NO in the in vivo brain [D. Luo, S. Knezevich, S.R. Vincent, N-Methyl-D-aspartate-induced nitric oxide release: an in vivo microdialysis study, Neuroscience, 57 (1993), 897-900; K. Ohta, N. Arai, M. Shibata, J. Hamada, S. Komatsumoto, K. Shimazu, Y. Fukuuchi, A novel in vivo system for consecutive measurement of brain nitric oxide production combined with the microdialysis technique, Neurosci. Lett., 176 (1994), 165-168; K. Shintani, S. Kanba, T. Nakai, K. Sato, G. Yagi, R. Kato, M. Arai, Measurement by in vivo microdialysis of nitric oxide release in the rat cerebellum, J. Psychiatr. Neurosci., 3 (1994), 217-221; H. Togashi, K. Mori, K. Ueno, M. Matsumoto, N. Suda, H. Saito, M. Yoshika, Consecutive evaluation of nitric oxide production after transient cerebral ischemia in the rat hippocampus using in vivo brain microdialysis, Neurosci. Lett., 240 (1998), 53-57]. Although several methods are available for detecting NO(x)(-) levels in dialysates, these methods are either not sensitive enough or require expensive experimental equipment. The method described herein provides a convenient and sensitive procedure for determining NO(x)(-) levels in dialysates. This method is useful for the in vivo study of NO production from various brain regions in various pathological conditions, and can be applied to other tissues.

Topics: Animals; Brain Ischemia; Corpus Striatum; Gerbillinae; Male; Microdialysis; Nitrates; Nitric Oxide; Sodium Nitrite

The antihypoxic effects of gutimine, piracetam, sodium hydroxybutyrate and lithium hydroxybityrate were studied on different models of brain hypoxia. All the drugs under study produced a remarkable antihypoxic effect in experimental asphyxic hypoxia, increasing brain resistance to oxygen deficiency and rapidly restituting brain function. Drug pretreatment of the animals with carotid artery occlusion raised the number of animals which survived 24 h after the operation. GABA salts appeared the most effective. Sodium hydroxybutyrate increased the lifespan of rats under histotoxic hypoxia.

Topics: Animals; Asphyxia; Brain Ischemia; Disease Models, Animal; Drug Evaluation, Preclinical; Electrocardiography; Electroencephalography; Guanylthiourea; Hydroxybutyrates; Hypoxia, Brain; Lithium; Male; Organometallic Compounds; Piracetam; Rats; Sodium Nitrite; Sodium Oxybate