Although several studies have shown that L-threo3,4-dihydroxyphenylserine (DOPS) may provide a neuroprotective effect against ischemic brain damage, its protective mechanism is not fully understood. Glutamate release and hippocampal blood flow in ischemia with administration of DOPS were investigated to elucidate the neuroprotective mechanism of DOPS. Pre- (but not post-) ischemic ...

INTRODUCTION: The ability to assess transmural changes in action potential duration during acute no-flow ischemia is essential to an understanding of the tachyarrhythmias that occur in this setting. The purpose of this study was to determine if activation recovery intervals determined from unipolar electrograms would provide this information. METHODS AND ...

The purpose of this study was to test the hypothesis that hyperglycemia ameliorates changes in brain cell membrane function and preserves cerebral high energy phosphates during hypoxia-ischemia in newborn piglets. A total of 42 ventilated piglets were divided into 4 groups, normoglycemic/normoxic(group 1, n=9), hyperglycemic/normoxic(group 2, n=8), normoglycemic/hypoxic-ischemic(group 3, n=13) ...

The vasodilator nitric oxide (NO) is involved in the regulation of systemic blood pressure and local organ blood flow. Inhibitors of the constitutively expressed nitric oxide synthase in endothelial cells (eNOS), e.g., Nomega-nitro-L-arginine methyl ester hydrochloride (L-NAME), aggravated liver injury in a variety of models. On the other hand, inhibitors ...

OBJECTIVE: To determine whether xanthine oxidase and dehydrogenase activities are altered during low flow ischemia and reperfusion of the small intestine of horses. ANIMALS: 5 clinically normal horses without histories of abdominal problems. PROCEDURE: With the horse under general anesthesia, a laparotomy was performed and blood flow to a segment ...

The effect of transient cerebral ischemia on phosphorylation of the microtubule-associated protein (MAP) tau was investigated using the rat four-vessel occlusion model. Phosphorylation of tau is proposed to regulate its binding to microtubules, influencing the dynamics of microtubule assembly necessary for axonal growth and neurite plasticity. In this study, tau ...

Neovascularization of ischemic muscle may be sufficient to preserve tissue integrity and/or function and may thus be considered to be therapeutic. The regulatory role of vascular endothelial growth factor (VEGF) in therapeutic angiogenesis was suggested by experiments in which exogenously administered VEGF was shown to augment collateral blood flow in ...

Stroke results from focal cerebral ischemia due to occlusion of a cerebral blood vessel, usually an artery. Where ischemia is chronic or intermittent, collateral circulation may develop by enlargement of preexisting anastomotic channels or sprouting of new capillaries from existing vessels (angiogenesis). Angiogenesis has three attributes of particular interest in ...

Interstitial levels of the neurotransmitter glutamate and cerebral blood flow changes were compared in two models of rat forebrain ischemia using the dialysis electrode technique and laser doppler flowmetry with brain temperature controlled. Ten-minute periods of cerebral ischemia were elicited by the four and an eleven vessel occlusion and compared ...

The objective of this study was to determine whether the duration of an ischemic insult effects the activity of the mitochondrial enzyme pyruvate dehydrogenase (PDH) in relation to the recovery of metabolites and regional cerebral blood flow (rCBF) immediately after ischemia and during reperfusion in gerbil cortex. Cerebral ischemia was ...

Leukocytes have been shown to contribute to ischemia-reperfusion injury in skeletal muscle. Pentoxifylline (PTXF), a xanthine-derived phosphodiesterase inhibitor, has received recent attention because of its action on leukocytes. To clarify the effects of PTXF in reperfusion injury, we measured the resting transmembrane potential difference (Em) and evaluated postcapillary venule microcirculation ...

Following prolonged limb ischemia, a reperfusion injury may occur with the reintroduction of unmodified blood, resulting in tissue loss and, in severe cases, limb loss. We have shown that the reperfusion injury in the heart can be minimized by using controlled reperfusion with a substrate-enriched cardioplegia solution prior to restoring ...

It is not easy to detect oxygen free radicals directly because of their very short half-life. In the present study, a sensitive ultra-weak chemiluminescence detector was used to detect the generation of oxygen free radicals following thermal injury. Twelve New Zealand white rabbits were used in this study. After anesthesia, ...

BACKGROUND: Terminal warm blood cardioplegia accelerates myocardial metabolic recovery. The process of myocardial oxygenation during terminal warm blood cardioplegia and its optimal administration are not clear. METHODS: We measured the myocardial tissue oxygen saturation (SO2) during reperfusion using near-infrared spectroscopy. Twenty-four dogs underwent 1 hour of ischemic arrest with cold ...

OBJECTIVE: Investigation of leukocyte sequestration in alveolar capillaries and of microhemodynamic changes after pulmonary ischemia/reperfusion injury. METHODS: The kinetics of leukocyte passage and the hemodynamics in pulmonary microcirculation were investigated in 16 rabbits by intravital microscopy. Mean red blood cell velocity and the number of sticking leukocytes were measured in ...

OBJECTIVE: To compare the effects of mild hypothermia induced in different time courses on rats subjected to 3 hours (h) of ischemia followed by 3 h or 72 h of reperfusion. METHODS: Eighty male Sprague-Dawley rats were divided into three mild hypothermic (MHT, 32 +/- 0.2 degrees C) groups, including ...

OBJECTIVE: To evaluate and compare oxidative processes during ischemia and reperfusion of the equine large colon and jejunum. ANIMALS: 2 groups of 6 anesthetized horses undergoing a terminal procedure. PROCEDURE: Isolated loops of large colon and jejunum were subjected to 2 hours of ischemia, followed by 2 hours of reperfusion. ...

BACKGROUND AND PURPOSE: Selective regional sensitivity and delayed damage in cerebral ischemia provide opportunities for directed and late therapy for stroke. Our aim was to characterize the spatial and temporal profile of ischemia-induced changes in cerebral perfusion and tissue status, with the use of noninvasive MRI techniques, to gain more ...

Intracellular acidosis has been considered to play an pivotal role in the progression of neuronal damage after cerebral ischemia. However, continuous measurement of the intracellular potential of hydrogen (pH) has not been done during and after ischemia. We measured temporal changes in intracellular pH in the feline cerebral cortex in ...

The results of a series of scanning electron microscopical studies were used to construct a model for the vascular pathways in the inner ear. Corrosion cast preparations of the vessels of the inner ear of the adult rat were used in this study. The inner ear is, like a hand, ...

We determined whether spatial distributions of substrate uptake are heterogeneous within the area at risk during reperfusion. Quantitative autoradiography with imaging plates and two long-lived radioisotopes was applied to 15 open-chest, anesthetized rats subjected to 30 min of coronary artery ligation and 30 min of reperfusion. Regions showing increased beta-methyl-[1-14C]heptadecanoic ...

A significant porportion (25%) of patients with Alzheimer's disease (AD) also shows vascular pathology. Recent ultrastructural studies demonstrated characteristic and extensive angio-architectural distortions of cerebral capillaries in AD brains. We examined the expression of APP mRNA isoforms of cerebral cortex after transient ischemia by middle cerebral artery occlusion, using RT-PCR. ...

There are different well established experimental models of low-flow ischemia. We examined metabolic variables during reduced coronary blood flow (CBF) in intact pig hearts and isolated neonatal pig hearts, producing similar degrees of postischemic dysfunction without infarction. The isolated hearts were perfused with red blood cell enriched buffer. In eight ...

This study was designed to investigate the simultaneous changes in blood flow and microcirculation in an island flap during venous occlusion (venous ischemia), in an ischemia/reperfusion injury model in the rabbit. An island groin flap based on the inferior epigastric vessels was harvested in 15 rabbits. The flap was rendered ...

Because hippocampal neurons are quite vulnerable to the anoxic brain injury that sometimes occurs in aortic arch surgery in humans, hippocampal ischemia should be a sensitive indicator of global cerebral ischemia. It was concluded that the hypothermic retrograde cerebral circulation technique for aortic arch surgery could not only be performed ...

Free radical production in the brain of acutely anesthetized, exteriorized lamb fetuses (n = 11, gestational age = 135 d) was measured using spin trap methodology. Communications between the vertebral and carotid circulations were tied, producing a two-vessel supply to the brain. Flow probes and occlusion slings were placed around ...

Temporary interruption or reduction of cerebral blood flow during cerebrovascular surgery may rapidly result in ischemia or cerebral infarction. Thiopental has been shown to have cerebroprotective effects. However, the cerebroprotective dose of thiopental causes burst suppression of the EEG, thus this parameter cannot be used continuously for the detection of ...

The observation that the free radical nitric oxide (NO) acts as a cell signaling molecule in key physiological processes such as regulation of blood pressure and immunological host-defense responses is probably one of the most important and exciting findings made in biology in the last decade. Likewise, in the brain ...

Stress proteins are important in protection during cardiac ischemia/reperfusion (cessation and return of blood flow) and are reportedly induced by electromagnetic (EM) fields. This suggests a possible ischemia protection role for EM exposures. To test this, chick embryos (96 h) were exposed to 60 Hz magnetic fields prior to being ...

Restoration of blood flow to an acute ischemic extremity may deteriorate the ischemic injury, lead to multiple organ dysfunction or even death. This paradox of continuing injury during reperfusion is not completely understood. The role of multi-organ damage in the mortality caused by ischemic limb injury is also still not ...

To investigate long-term adaptations after unilateral carotid artery ligation, the effect of forebrain ischemia on cerebral blood flow and ATP levels was determined at various times after ligation. Unilateral carotid artery ligation was performed in male Wistar rats 0, 3, or 7 days before forebrain ischemia. Laser-Doppler blood flow was ...

The aim of the present study is to compare the influence of timing and duration of mild hypothermia on rats subjected to 3 h of middle cerebral artery occlusion followed by 72 h of reperfusion. Sixty-four Sprague-Dawley rats were divided into three mild hypothermic groups according to the duration of ...

The purpose of this manuscript is to briefly review the pathophysiology of cerebral ischemia. Ischemic thresholds are well-defined in lower animals. The concept of the ischemic penumbra may include regions of brain around deeper regions of ischemia but has also been defined in terms of brain salvageable by reperfusion or ...

The contribution of the complement system to the exacerbation of cerebral ischemia/reperfusion injury was studied by comparing a group of rats with normal complement levels to another group that was complement depleted by cobra venom factor (CVF). The magnitude of reactive hyperemia was significantly greater in the complement depleted animals. ...

The effects of intraportal administration of prostaglandin E1 (PGE1) on portal venous flow, hepatic arterial flow, peripheral tissue blood flow, and systemic arterial flow before and after 60 min total liver ischemia followed by 70% partial hepatectomy in rats were investigated. Total liver ischemia was induced by occluding the hepatoduodenal ...

To determine the effect of platelet-activating factor (PAF) antagonist L-691,880 on low-flow ischemia and reperfusion (I-R) of the large colon in horses. 12 adult horses. Horses were anesthetized, and the large colon was exteriorized through a ventral median celiotomy and instrumented. Colonic arterial blood flow was reduced to 20% of ...

Forty-four patients with severe head injury were monitored for episodes of cerebral ischemia using jugular venous oxygen saturation (sjvO2), brain tissue pO2 (ti-pO2), and a microdialysis probe. The concentration of lactate and glucose were measured in the microdialysate. A total of 10 episodes of global ischemia were observed. The characteristic ...

The role of polymorph nuclear neutrophils (PMN) in limb ischemia and reperfusion has been recognized only in recent years. The present study aimed to investigate the systemic and local (in femoral venous blood) effects of intra-arterially or intravenously applied prostaglandin E1 (PGE1) on systemic and ischemia-induced local changes in neutrophil ...

Cytosolic Ca2+ overload has been proposed as a main cause of neuronal injury during cerebral ischemia. SNX-111, a synthetic product of the naturally occurring omega-conotoxin MVIIA, is a novel, presynaptic N-type Ca2+ channel antagonist and has been reported to be neuroprotective against cerebral ischemia. We studied the neuroprotective effects of ...

Polyamines and N-methyl-D-aspartate (NMDA) receptors are both thought to play an important role in secondary neuronal injury after cerebral ischemia. Ifenprodil, known as a noncompetitive inhibitor of polyamine sites at the NMDA receptor, was studied after transient focal cerebral ischemia occurred. Spontaneously hypertensive male rats, each weighing between 250 and ...

We preformed this study to determine the effect on ocular blood flow and the electroretinogram of either nitric oxide synthase (NOS) inhibition, adenosine receptor blockade or the combination of both after 1 hr of ocular ischemia. Thirty-seven cats under general anesthesia were subjected to 1 hr of complete ischemia in ...

BACKGROUND: We have previously demonstrated that ischemic preconditioning (PC) does not protect when oxygen deprivation is accompanied by a high level of perfusion (hypoxia). Since clinical ischemia can vary from mild to severe, we wished to determine whether PC could protect against injury arising from low-flow ischemia. METHODS AND RESULTS: ...

BACKGROUND: Adenosine has several potentially cardioprotective effects. We hypothesized that the effects of endogenous adenosine vary with degree of ischemia and that elevating endogenous levels is protective. METHODS AND RESULTS: Isolated blood-perfused piglet hearts underwent 120 minutes of low-flow ischemia (10% flow) or 90 minutes of zero-flow ischemia, all with ...

After a period of global cerebral ischemia, CO2 reactivity and the hemodynamic-metabolic activation to functional stimulation are transiently suppressed. This raises the question of whether the impaired functional coupling reflects disturbances of functional integrity of the brain or an impaired cerebrovascular reactivity. We, therefore, compared the recovery of CO2 reactivity ...

BACKGROUND: Gut injury due to ischemia and reperfusion (I/R) plays a pivotal role in many clinical conditions, such as small bowel transplantation, heart or aortic surgery in adults, and necrotizing enterocolitis in neonates. The influence of ischemic events on microcirculatory mechanisms is not well understood. Therefore, we studied, in vivo, ...

BACKGROUND: Effects of no-flow ischemia and reperfusion on myocardial extraction and retention of 99mTc-labeled tetrofosmin and 201Tl were investigated in seven isolated, blood-perfused rat hearts with isotope dilution studies at constant coronary perfusion. METHODS AND RESULTS: After a control injection of tracers, no-flow ischemia was induced for 20 minutes. After ...

The purpose of these experiments was to evaluate two methods of bowel viability assessment in two distinct models of intestinal ischemia. Bowel viability was assessed in 32 dogs by means of three methods: (1) a probe that quantified the intestinal electromyographic (EMG) measurements in millivolts (mV), (2) Doppler ultrasonography, and ...

AIM: To study the effects of dl-3-n-butylphthalide (NBP) on the changes of thromboxane B2 (TXB2) and 6-keto-PGF1 alpha (6-keto-PGF1 alpha) contents in hippocampus, striatum, and cerebral cortex of rats subjected to focal cerebral ischemia followed by reperfusion. METHODS: Focal cerebral ischemia was induced by inserting a nylon suture into intracranial ...

Brain swelling is a serious complication associated with focal ischemia in stroke and severe head injury. Experimentally, reperfusion following focal cerebral ischemia exacerbates the level of brain swelling. In this study, the permeability of the blood-brain barrier has been investigated as a possible cause of reperfusion-related acute brain swelling. Blood-brain ...

Intestinal ischemia and reperfusion elicits changes in leukocyte counts and increased production of reactive oxygen species (ROS). The purpose of this study was to investigate whether these changes were followed by and/or connected with changes in the extracellular antioxidative capacity in a rat superior mesenteric artery (SMA) occlusion/reperfusion model. The ...