Effects of nitric oxide on reactive oxygen species production and infarction size after brain reperfusion injury

Timing is everything: Exercise therapy and remote ischemic conditioning for acute ischemic stroke patients

Physical exercise is a promising rehabilitative strategy for acute ischemic stroke. Preclinical trials suggest that exercise restores cerebral blood circulation and re-establishes the blood–brain barrier’s integrity with neurological function and motor skill improvement. Clinical trials demonstrated that exercise improves prognosis and decreases complications after ischemic events. Due to these encouraging findings, early exercise rehabilitation has been quickly adopted into stroke rehabilitation guidelines. Unfortunately, preclinical trials have failed to warn us of an adverse effect. Trials with very early exercise rehabilitation (within 24 h of ischemic attack) found an inferior prognosis at 3 months. It was not immediately clear as to why exercise was detrimental when performed very early while it was ameliorative just a few short days later. This review aimed to explore the potential mechanisms of harm seen in very early exercise administered to acute ischemic stroke patients. To begin, the mechanisms of exercise’s benefit were transposed onto the current understanding of acute ischemic stroke’s pathogenesis, specifically during the acute and subacute phases. Then, exercise rehabilitation’s mechanisms were compared to that of remote ischemic conditioning (RIC). This comparison may reveal how RIC may be providing clinical benefit during the acute phase of ischemic stroke when exercise proved to be harmful.

Design, Synthesis, and Biological Evaluation of Organic Nitrite (NO2-) Donors as Potential Anticerebral Ischemia Agents

The treatment of ischemic stroke (IS) remains a big challenge in clinics, and it is urgently needed to develop novel, safe, and effective medicines against IS. Here, we report the design, synthesis, and biological evaluation of organic NO₂^- donors as potential agents for the treatment of IS. The representative compound 4a was able to slowly generate low concentrations of NO₂^- by reaction with a thiol-containing nucleophile, and the NO₂^- was selectively converted into NO under ischemic/hypoxia conditions to protect primary rat neurons from oxygen-glucose deprivation and recovery (OGD/R)-induced cytotoxicity by enhancing the Nrf2 signaling and activating the NO/cGMP/PKG pathway. Treatment with 4a at 2 h before or after ischemia mitigated the ischemia/reperfusion-induced brain injury in middle cerebral artery occlusion (MCAO) rats by producing NO and enhancing Nrf2 signaling. Furthermore, 4a significantly promoted endothelial cell proliferation and angiogenesis within the ischemic penumbra. Our findings suggest that this type of NO₂^- donors, like 4a, may be valuable to fight IS and other ischemic diseases.

Pharmacological Characterizations of anti-Dementia Memantine Nitrate via Neuroprotection and Vasodilation in Vitro and in Vivo

We have previously designed and synthesized a series of novel memantine nitrates, and some of them have shown neuroprotective effects; however, the detailed mechanisms remain unknown. In this study, we demonstrated that MN-12, one of the memantine nitrates, concentration-dependently protected against glutamate-induced neurotoxicity in rat primary cultured cerebellar granule neurons (CGNs). Western blotting assays revealed that MN-12 might possess neuroprotective effects through the inhibition of ERK pathway and activation of PI3K/Akt pathway concurrently. Moreover, MN-12 concentration-dependently dilated precontracted rat middle cerebral artery through activation of NO-cGMP pathway ex vivo. In the 2-vessel occlusion (2VO) rat model, MN-12 alleviated the impairments of spatial memory and motor dysfunction possibly via neuroprotection and improvement of the cerebral blood flow. Furthermore, the results of preliminary pharmacokinetic studies showed that MN-12 might quickly distribute to the major organs including the brain, indicating that MN-12 could penetrate the blood-brain barrier. Taken together, MN-12 might provide multifunctional therapeutic benefits for dementia associated with Alzheimer's disease, vascular dementia, and ischemic stroke, via neuroprotection and vessel dilation to improve the cerebral blood flow.

Intravenous thrombolysis in combination with mild hypothermia therapy in the treatment of acute cerebral infarction

Objective

To investigate the efficacy of recombinant tissue plasminogen activator (rt-PA) intravenous thrombolysis in combination with mild hypothermia therapy in the treatment of acute cerebral infarction.

Methods

One hundred and thirty-two patients with acute cerebral infarction who were admitted to our hospital were selected and grouped into a control group and an observation group, 66 each group. Patients in the control group were given conventional treatment in combination with local mild hypothermia therapy, and patients in the observation group were given rt-PA intravenous thrombolysis on the basis of conventional treatment and local mild hypothermia therapy. National institute of health stroke scale (NIHSS) score and intracranial pressure (ICP) of the two groups before and after treatment was recorded. The efficacy of the two groups was evaluated. The modified Rankin scale (MRS) score was followed up for three months. The blood samples of the patients were collected before and after thrombolysis. Superoxide dismutase (SOD) and malondialdehyde (MDA) levels in the plasma were detected.

Results

The NIHSS score of the two groups decreased in the 1^st, 3^rd and 7^th day after treatment compared to before treatment (p<0.05), but the NIHSS score of the two groups had no significant difference at different time points after treatment (p>0.05). The ICP of the two groups decreased in the 1^st, 3^rd and 7^th day after treatment compared to before treatment (p<0.05), and the decrease of ICP of the observation group was more significant than that of the control group at the same time point (1^st, 3^rd and 7^th day after treatment) (p<0.05). The clinical efficacy of the observation group was higher than that of the control group after treatment, and the difference was statistically significant (p<0.05). The MDA concentration of both groups decreased at different time points after treatment (p<0.05), but the SOD concentration increased (p<0.05). The MDA concentration of the observation group was lower than that of the control group at different time points after treatment (p<0.05), and the SOD concentration of the observation group was higher than that of the control group (p<0.05).

Conclusion

rt-PA intravenous thrombolysis in combination with mild hypothermia therapy has significant efficacy in the treatment of acute cerebral infarction. It can effectively relieve neurological function. Its action mechanism may be realized by relieving oxidative stress response.

Neuroprotective mechanism of low-dose sodium nitrite in oxygen-glucose deprivation model of cerebral ischemic stroke in PC12 cells

The purpose of this study was to clarify the mechanisms of the protective effects of low-dose sodium nitrite (SN) on oxygen and glucose deprivation (OGD)-induced endoplasmic reticulum (ER) stress in PC12 cells. The PC12 cells were exposed to 4 h of OGD and treated with 100 μmol SN. The expression and activity of ER stress markers, including PKR-like endoplasmic reticulum kinase (PERK), transcription factor 6 (ATF6), CCAAT/enhancer binding protein homologous protein (CHOP), as well as caspase-12 and -3, were detected by immunoblotting assay. Fluorescence staining was used to detect the levels of reactive oxygen species (ROS) and Ca²⁺ release from the ER. Cell viability was also evaluated by MTT assay. It was found that SN significantly inhibited ROS production and Ca²⁺ release from the ER in OGD-injured PC12 cells. Moreover, ER stress marker expression and cleaved fragments of caspase-3 and -12 in OGD-injured PC12 cells were decreased after SN treatment. These findings were accompanied by a significant increase in cell viability. It seems that SN exerts a neuroprotective effect at least partially through reduction of ROS-mediated ER stress caused by OGD insult.

Imaging of prehospital stroke therapeutics

Despite significant quality improvement efforts to streamline in-hospital acute stroke care in the conventional model, there remain inherent layers of treatment delays, which could be eliminated with prehospital diagnostics and therapeutics administered in a mobile stroke unit. Early diagnosis using telestroke and neuroimaging while in the ambulance may enable targeted routing to hospitals with specialized care, which will likely improve patient outcomes. Key clinical trials in telestroke, mobile stroke units with prehospital neuroimaging capability, prehospital ultrasound and co-administration of various classes of neuroprotectives, antiplatelets and antithrombin agents with intravenous thrombolysis are discussed in this article.

Metallothionein-II inhibits lipid peroxidation and improves functional recovery after transient brain ischemia and reperfusion in rats

After transient cerebral ischemia and reperfusion (I/R), damaging mechanisms, such as excitotoxicity and oxidative stress, lead to irreversible neurological deficits. The induction of metallothionein-II (MT-II) protein is an endogenous mechanism after I/R. Our aim was to evaluate the neuroprotective effect of MT-II after I/R in rats. Male Wistar rats were transiently occluded at the middle cerebral artery for 2 h, followed by reperfusion. Rats received either MT (10 μg per rat i.p.) or vehicle after ischemia. Lipid peroxidation (LP) was measured 22 h after reperfusion in frontal cortex and hippocampus; also, neurological deficit was evaluated after ischemia, using the Longa scoring scale. Infarction area was analyzed 72 hours after ischemia. Results showed increased LP in frontal cortex (30.7%) and hippocampus (26.4%), as compared to control group; this effect was fully reversed by MT treatment. Likewise, we also observed a diminished neurological deficit assessed by the Longa scale in those animals treated with MT compared to control group values. The MT-treated group showed a significant (P < 0.05) reduction of 39.9% in the infarction area, only at the level of hippocampus, as compared to control group. Results suggest that MT-II may be a novel neuroprotective treatment to prevent ischemia injury.

Pre-Hospital Glyceryl Trinitrate: Potential for Use in Intracerebral Hemorrhage

BACKGROUND

Intracerebral hemorrhage is associated with poor clinical outcome and high mortality. Research and treatment modalities have focused on the expansion of the primary hematoma through blood pressure control and activation of coagulation factors. However, clinical trials have failed to show decreased rates of death or disability in intracerebral hemorrhage following hospital initiation of blood pressure control. However, as clinical deterioration often occurs immediately after onset, pre-hospital initiation of blood pressure control may be more ideal.

METHODS

Relevant terms in the National Library of Medicine PubMed database and selected research including basic science, translational reports, meta-analyses, and clinical studies were searched.

RESULTS

Trends indicating improved clinical outcome in intracerebral hemorrhage after hospital-initiated intensive systolic blood pressure control (goal<140 mmHg) have been demonstrated. Statistical significance may not have been obtained because of late treatment times of blood pressure control that approached median 4-6 hours after clinical onset. One trial utilizing glyceryl trinitrate in the pre-hospital setting has been shown to significantly decrease blood pressure within fifteen minutes and improve 90-day clinical outcome.

CONCLUSIONS

Glyceryl trinitrate represents an ideal pre-hospital blood pressure medication because it can be delivered via sublingual or transdermal routes, has a quick and graded onset of action, has neuroprotective effects, maintains cerebral perfusion, and has an established record of safety. As intracerebral hemorrhage requires prompt action to prevent clinical deterioration, more emphasis on pre-hospital therapies for blood pressure reduction will become essential in future therapies.

Nitric oxide donors as neuroprotective agents after an ischemic stroke-related inflammatory reaction

Cerebral ischemia initiates a cascade of detrimental events including glutamate-associated excitotoxicity, intracellular calcium accumulation, formation of Reactive oxygen species (ROS), membrane lipid degradation, and DNA damage, which lead to the disruption of cellular homeostasis and structural damage of ischemic brain tissue. Cerebral ischemia also triggers acute inflammation, which exacerbates primary brain damage. Therefore, reducing oxidative stress (OS) and downregulating the inflammatory response are options that merit consideration as potential therapeutic targets for ischemic stroke. Consequently, agents capable of modulating both elements will constitute promising therapeutic solutions because clinically effective neuroprotectants have not yet been discovered and no specific therapy for stroke is available to date. Because of their ability to modulate both oxidative stress and the inflammatory response, much attention has been focused on the role of nitric oxide donors (NOD) as neuroprotective agents in the pathophysiology of cerebral ischemia-reperfusion injury. Given their short therapeutic window, NOD appears to be appropriate for use during neurosurgical procedures involving transient arterial occlusions, or in very early treatment of acute ischemic stroke, and also possibly as complementary treatment for neurodegenerative diseases such as Parkinson or Alzheimer, where oxidative stress is an important promoter of damage. In the present paper, we focus on the role of NOD as possible neuroprotective therapeutic agents for ischemia/reperfusion treatment.

Preconditioning with a novel metallopharmaceutical NO donor in anesthetized rats subjected to brain ischemia/reperfusion

Rut-bpy is a novel nitrosyl-ruthenium complex releasing NO into the vascular system. We evaluated the effect of Rut-bpy (100 mg/kg) on a rat model of brain stroke. Forty rats were assigned to four groups (Saline solution [SS], Rut-bpy, SS+ischemia-reperfusion [SS+I/R] and Rut-bpy+ischemia-reperfusion [Rut-bpy+I/R]) with their mean arterial pressure (MAP) continuously monitored. The groups were submitted (SS+I/R and Rut-bpy+I/R) or not (SS and Rut-bpy) to incomplete global brain ischemia by occlusion of the common bilateral carotid arteries during 30 min followed by reperfusion for further 60 min. Thirty minutes before ischemia, rats were treated pairwise by intraperitoneal injection of saline solution or Rut-bpy. At the end of experiments, brain was removed for triphenyltetrazolium chloride staining in order to quantify the total ischemic area. In a subset of rats, hippocampus was obtained for histopathology scoring, nitrate and nitrite measurements, immunostaining and western blotting of the nuclear factor- κB (NF-κB). Rut-bpy pre-treatment decreased MAP variations during the transition from brain ischemia to reperfusion and decreased the fractional injury area. Rut-bpy pre-treatment reduced NF-κB hippocampal immunostaining and protein expression with improved histopathology scoring as compared to the untreated operated control. In conclusion, Rut-bpy improved the total brain infarction area and hippocampal neuronal viability in part by inhibiting NF-κB signaling and helped to stabilize the blood pressure during the transition from ischemia to reperfusion.

Safety and feasibility of long-term intravenous sodium nitrite infusion in healthy volunteers

Background

Infusion of sodium nitrite could provide sustained therapeutic concentrations of nitric oxide (NO) for the treatment of a variety of vascular disorders. The study was developed to determine the safety and feasibility of prolonged sodium nitrite infusion.

Methodology

Healthy volunteers, aged 21 to 60 years old, were candidates for the study performed at the National Institutes of Health (NIH; protocol 05-N-0075) between July 2007 and August 2008. All subjects provided written consent to participate.

Twelve subjects (5 males, 7 females; mean age, 38.8±9.2 years (range, 21–56 years)) were intravenously infused with increasing doses of sodium nitrite for 48 hours (starting dose at 4.2 µg/kg/hr; maximal dose of 533.8 µg/kg/hr). Clinical, physiologic and laboratory data before, during and after infusion were analyzed.

Findings

The maximal tolerated dose for intravenous infusion of sodium nitrite was 267 µg/kg/hr. Dose limiting toxicity occurred at 446 µg/kg/hr. Toxicity included a transient asymptomatic decrease of mean arterial blood pressure (more than 15 mmHg) and/or an asymptomatic increase of methemoglobin level above 5%. Nitrite, nitrate, S-nitrosothiols concentrations in plasma and whole blood increased in all subjects and returned to preinfusion baseline values within 12 hours after cessation of the infusion. The mean half-life of nitrite estimated at maximal tolerated dose was 45.3 minutes for plasma and 51.4 minutes for whole blood.

Conclusion

Sodium nitrite can be safely infused intravenously at defined concentrations for prolonged intervals. These results should be valuable for developing studies to investigate new NO treatment paradigms for a variety of clinical disorders, including cerebral vasospasm after subarachnoid hemorrhage, and ischemia of the heart, liver, kidney and brain, as well as organ transplants, blood-brain barrier modulation and pulmonary hypertension.

Clinical Trial Registration Information

http://www.clinicaltrials.gov; NCT00103025

Differential effects of nitric oxide on blood-brain barrier integrity and cerebral blood flow in intracerebral C6 gliomas

Nitric oxide (NO) signaling in tumors and endothelial cells regulates vascular permeability and blood flow and therefore influences tumor uptake and response to therapeutic compounds. As delivery and efficacy of chemotherapy is impaired in CNS neoplasms due to a partially intact blood-brain barrier (BBB), we studied the effects of NO released by the short-acting NO donor disodium 1-[2-(carboxylato)pyrrolidin-1-yl]diazen-1-ium-1,2-diolate methanolate (PROLI/NO) on BBB integrity and blood flow in C6 gliomas using [¹⁴C]-aminoisobutyric acid (AIB) and [¹⁴C]-iodoantipyrine quantitative autoradiography. PROLI/NO selectively increased intratumoral uptake of [¹⁴C]AIB and [¹⁴C]sucrose when given as a 3-minute intracarotid infusion or a 15-minute i.v. infusion (AIB: tumor, K₁ = 68.7 ± 3.2 vs 24.9 ± 0.9 µL g⁻¹ min⁻¹, P < .0001; sucrose, K₁ = 16.9 ± 0.9 vs 11.5 ± 0.9 µL g⁻¹ min⁻¹, P = .0007). This effect was achieved without significant changes in cerebral and tumor blood flow or arterial blood pressure, which indicates that the effect on vascular permeability is independent of changes in vascular tone induced by NO. This effect was mediated by activation of the NO/3',5'-cyclic guanosine monophosphate (cGMP) pathway, as it was blocked by guanylate cyclase inhibition by LY83583 and reproduced by the delivery of 8-bromoguanosine 5'-monophosphate or inhibition of cGMP degradation by the phosphodiesterase inhibitor zaprinast. Inhibition of inducible NO synthase by aminoguanidine or cyclooxygenase inhibition by indometacin or dexamethasone did not reduce the blood-tumor barrier (BTB) response to PROLI/NO. PROLI/NO, and perhaps other NO-donating compounds, can be used to selectively increase BTB permeability in gliomas through the NO/cGMP pathway at doses that do not cause unwanted vasodilatory changes in blood flow and that do not affect the systemic circulation.

Role of sensory C fibers in hypoxia/reoxygenation-impaired myogenic constriction of cerebral arteries

OBJECTIVE

Hypoxia/reoxygenation (H/R) associated with extracorporeal membrane oxygenation disrupts cerebral autoregulation. However, the underlying mechanisms remain poorly understood. The present study was designed to investigate the role of sensory C-fibers in myogenic responsiveness of cerebral arteries.

METHODS

Arterial diameter and intraluminal pressure were simultaneously measured in vitro on rat posterior cerebral arteries.

RESULTS

Cerebral arteries constricted in response to graded increase in intraluminal pressure (20-100 mmHg, in 20 mmHg increments). In vitro C-fiber desensitization with capsaicin (1 micromol/l, 20 minutes) significantly suppressed myogenic constriction by over 50%, but did not affect 5-hydroxytryptamine (0.01-10 micromol/l) and KCl (120 mmol/l)-induced constriction. Capsazepine (5 micromol/l, 30 minutes), a selective blocker of neuronal vanilloid receptor TRPV1, had similar inhibitory effect on cerebral myogenic constriction to elevated pressure. Cerebral myogenic constriction was significantly attenuated by H/R; the impairment by H/R was further enhanced after C-fiber desensitization (except at a pressure level of 100 mmHg).

DISCUSSION

These findings indicate that C-fiber activity contributes to myogenic constriction of cerebral arteries under normal and H/R conditions. H/R-impaired myogenic responsiveness is exaggerated by C-fiber dysfunction. These results raise the possibility that therapeutic strategies directed toward preserving C-fiber nerve endings or supplying its constituent neuropeptides could be developed.

Minocycline attenuates cognitive impairment and restrains oxidative stress in the hippocampus of rats with chronic cerebral hypoperfusion

OBJECTIVE

Nitric oxide (NO) was speculated to play an important role in the pathophysiology of cerebral ischemia. Minocycline, a tetracycline derivative, reduced inflammation and protected against cerebral ischemia. To study the neuroprotection mechanism of minocycline for vascular dementia, the influences of minocycline on expressions of inducible nitric oxide synthase (iNOS) and endothelial nitric oxide synthase (eNOS) were observed in the brains of Wistar rats.

METHODS

The vascular dementia rat model was established by permanent bilateral common carotid arteries occlusion (BCCAO). Wistar rats were divideded into 3 groups randomly: sham-operation group (S group), vascular dementia model group (M group), and minocycline treatment group (MT group). The behaviour was tested with Morris water maze and open-field task. Expressions of iNOS and eNOS were measured by immunohistochemistry and reverse transcriptase-polymerase chain reaction (RT-PCR). The optical density value was measured by imaging analysis. Percentage of positive cells with iNOS and eNOS expression was analyzed with optical microscope.

RESULTS

Minocycline attenuated cognitive impairment. Inducible NOS was significantly down-regulated in MT group, compared with that in M group (P < 0.01), while eNOS was significantly up-regulated, compared with that in M group (P < 0.01). The expressions of iNOS and eNOS in M and MT groups were higher than those in S group (P < 0.01).

CONCLUSION

Minocycline can down-regulate the expression of iNOS and up-regulate the expression of eNOS in vascular dementia, which restrains apoptosis and oxidative stress to protect neural function.

Nitrite does not provide additional protection to thrombolysis in a rat model of stroke with delayed reperfusion

An adjuvant therapy to prolong the therapeutic window for stroke patients is urgently needed. This randomized, blinded, placebo-controlled study investigated adjuvant intravenous sodium nitrite with recombinant tissue plasminogen activator (rtPA) in middle cerebral artery occlusion (MCAO) with 6 and 2 h of ischemia followed by reperfusion in Sprague-Dawley rats (n=59). Quantitative diffusion, T(1)-, T(2)-weighted, and semiquantitative perfusion imaging were performed before and after reperfusion and at 48 h after ischemia to determine the spatiotemporal evolution of stroke. After 48 h animals were killed and examined to evaluate infarct size and evidence of hemorrhagic transformation. Factor VIII immunostaining was performed to assess vessel morphology. Nitrite treatment (6 h group: 37.5 micromol for more than 90 mins; 2 h group: 26.25 and 1.75 micromol for more than 60 mins) did not reduce infarct volume 48 h after MCAO compared with saline-treated placebo groups after 6 or 2 h of MCAO. Stroke progression from baseline to 48 h, based on the apparent diffusion coefficient and relative cerebral blood flow deficits before and after reperfusion and T(2)-weighted hyperintensity at 48 h, did not differ between treated and control animals. These results suggest that nitrite is not a protective adjuvant therapy to delayed rtPA administration after ischemic stroke in rats.

Hyperglycemia in acute ischemic stroke: a vascular perspective

Admission hyperglycemia complicates approximately one-third of acute ischemic strokes and is associated with a worse clinical outcome. Both human and animal studies have showed that hyperglycemia is particularly detrimental in ischemia/reperfusion. Decreased reperfusion blood flow has been observed after middle cerebral artery occlusion in acutely hyperglycemic animals, suggesting the vasculature as an important site of hyperglycemic reperfusion injury. This paper reviews biochemical and molecular pathways in the vasculature that are rapidly affected by hyperglycemia and concludes that these changes result in a pro-vasoconstrictive, pro-thrombotic and pro-inflammatory phenotype that renders the vasculature vulnerable to reperfusion injury. Understanding these pathways should lead to the development of rational therapies that reduce hyperglycemic reperfusion injury and thus improve outcome in this large subset of acute ischemic stroke patients.

A nitric oxide donor reduces brain injury and enhances recovery of cerebral blood flow after hypoxia-ischemia in the newborn rat

Nitric oxide (NO) released in response to hypoxia-ischemia (HI) in the newborn brain may mediate both protective and pathologic responses. We sought to determine whether pharmacologic increase of NO using an NO donor would reduce neurologic injury resulting from HI in the postnatal day 7 rat. We measured NO levels and CBF in the presence of either a NOS inhibitor, N-nitro-l-arginine methyl ester (L-NAME) or an NO donor (Z)-1-[N-(2-amino-ethyl)-N-(2-ammonio-ethyl)amino]diazen-1-ium-1,2-diolate (DETANONOate). Both inhibition of NOS and administration of an NO donor reduced neuropathologic injury after 7-day recovery. NO levels decreased in both ischemic and contralateral hemispheres during HI. This response was prevented by treatment with DETANONOate. Despite the decrease in NO, CBF increased during ischemia in the contralateral hemisphere but decreased when combined with brief hypoxia. Treatment with L-NAME abolished these increases, which were not altered by DETANONOate. Reduction of cellular metabolism by mild hypothermia also reduced both NO and CBF. Following prolonged HI, CBF remained decreased in the ischemic hemisphere up to 24-h recovery. This decrease was prevented by treatment with DETANONOate. These data show that administration of an NO donor reduces neurologic injury following HI in the newborn rat. This mechanism of this protection, in part, is due to an increase in the rate of recovery of CBF compared to vehicle-treated animals. Augmentation of NO-dependent increases in CBF may serve to improve neurologic outcome after perinatal asphyxia.

Acute reduction of myocardial infarct size by a hydroxymethyl glutaryl coenzyme A reductase inhibitor is mediated by endothelial nitric oxide synthase

In addition to their lipid-lowering properties, statins improve endothelial function by increasing the activity of endothelial nitric oxide synthase (eNOS). It was hypothesized that, by this mechanism, statins protect the myocardium from ischemia/reperfusion injury in normocholesterolemic animals. Rats were pretreated for 1 week with either cerivastatin (0.3 mg/kg/d) or placebo. Anesthetized animals underwent 30 minutes of coronary artery occlusion (CAO) followed by 180 minutes of reperfusion. In a separate set of experiments, the NOS inhibitor l-NAME (15 mg/kg; N -nitro-l-arginine methyl ester) was administered 15 minutes before CAO. Cerivastatin decreased infarct size by 49% (P < 0.05) without reducing plasma cholesterol levels. Cerivastatin increased myocardial eNOS mRNA and NOS activity and by 52% and 58% (P < 0.05), respectively. Cardioprotection and upregulation of eNOS activity evoked by cerivastatin were not observed in rats cotreated with l-NAME. These results show that statins reduce the extent of myocardial necrosis in normocholesterolemic rats after acute ischemia/reperfusion injury by increasing myocardial eNOS activity. Therefore, statins may protect the heart not only by reducing the incidence of ischemic events, but also by limiting cell damage during acute myocardial infarction.