Biomedical subjects

G Z Feuerstein

Publications and source records attributed to G Z Feuerstein.

At least 109 records · Page 6Linked to original sources

PubMed1995

Mob-1 expression in IL-2-induced ARDS: regulation by TNF-alpha.

We have recently established an animal model of adult respiratory distress syndrome (ARDS)-like microvascular lung injury elicited by infusion of human interleukin-2 (IL-2). Based on the pronounced, transcriptional upregulation of multiple pro-inflammatory mediators in IL-2-induced ARDS, differential display was applied to search for potentially novel genes in this paradigm of lung injury. Differential display on total lung RNA derived from IL-2-challenged rats presented a highly reproducible 3'-UTR fragment profile in which a band (approximately 250 bp), termed B1, was strongly induced. B1 cDNA sequence exhibited 99.14% homology to the 3'-UTR of mob-1, a recently cloned gene belonging to the C-X-C chemokine superfamily. Furthermore, Northern blot analysis showed that IL-2-induced pulmonary mob-1 mRNA was expressed at time points before the onset of lung injury and suppressed after TNF-alpha inhibition. These data imply that lung mob-1 is a novel, highly inducible gene in a clinically relevant model of ARDS and, based on its identification as a chemokine, could participate in the development of lung injury.

Amino Acid Sequence↗

PubMed1995

Carvedilol, a new beta-adrenoreceptor blocker antihypertensive drug, protects against free-radical-induced endothelial dysfunction.

We tested the ability of carvedilol, an antihypertensive beta-adrenoreceptor antagonist with antioxidant properties, to protect rat aorta rings from free-radical-induced endothelial cell (EC) dysfunction. Rings were exposed to the superoxide generator pyrogallol. Vascular function of intact rings was assessed by observing acetylcholine (ACh)-induced vasorelaxation following submaximal contraction by U-46619. Function of rings denuded of ECs was assessed by observing S-nitroso-N-acetylpenicillamine (SNAP)-induced vasorelaxation following submaximal contraction by U-46619. Carvedilol exerted a significant protective effect against pyrogallol-induced vasoconstriction (17.1 +/- 4.8 vs. 31.9 +/- 5.4% for vehicle, p < 0.05). Carvedilol also demonstrated significant protection against pyrogallol-induced endothelium dysfunction, enhancing vasorelaxation to 1,000 nmol/l ACh (73 +/- 3.9 vs. 48 +/- 3.0% vehicle, p < 0.01). These protective effects were not seen with propanolol, a pure beta-receptor antagonist. Carvedilol mixed with pyrogallol and SNAP preserved SNAP-induced vasorelaxation in rings denuded of ECs (80.4 +/- 5.3 vs. 63.7 +/- 4.8% control, p < 0.05). Carvedilol appears to protect vascular function by scavenging free radicals and enhancing the effects of NO.

Acetylcholine↗

PubMed1995

Antihypertensive actions of the novel nonpeptide endothelin receptor antagonist SB 209670.

Indirect evidence has implicated endothelin-1 in the pathogenesis of hypertension. In the present study we examined such a role directly with SB 209670, a novel nonpeptide endothelin receptor antagonist. The antihypertensive and hemodynamic effects of SB 209670 were examined in conscious, unrestrained spontaneously hypertensive (SHR), normotensive Wistar-Kyoto (WKY), and renin-hypertensive rats. Sustained intravenous infusion of SB 209670 (10 micrograms.kg-1.min-1 for 6 hours) produced a significant, reversible reduction in mean arterial pressure in SHR but not in WKY rats. The antihypertensive response to 10 micrograms.kg-1.min-1 SB 209670 (approximately 25 mm Hg reduction in blood pressure) was associated with bradycardia (16% decrease in heart rate) but only a minimal reduction (3%) in cardiac output, because stroke volume was evaluated (by 15%). Therefore, the antihypertensive effect of SB 209670 resulted from a decrease (13%) in total peripheral resistance. A sustained antihypertensive effect could also be observed after intraduodenal administration of SB 209670 (3 mg/kg) in conscious SHR (reduction of approximately 35 mm Hg 5 hours after administration). SB 209670 (3 mg/kg intravenous bolus) did not alter the pressor response or tachycardia observed in pithed SHR after stimulation of thoracolumbar sympathetic outflow. SB 209670 was also antihypertensive in renin-hypertensive rats, lowering blood pressure to an extent similar to that observed in SHR. Thus, the data presented provide evidence to support a role for endothelin-1 in the pathophysiology of two animal models of hypertension.

Animals↗

PubMed1995

Monocyte chemoattractant protein-1 messenger RNA expression in rat ischemic cortex.

BACKGROUND AND PURPOSE: Previously we demonstrated that focal cerebral ischemia results in an increased expression of several cytokines/chemokines that precede the infiltration of leukocytes into the ischemic cortex after focal stroke induced by occlusion of the middle cerebral artery (MCAO). Monocyte chemoattractant protein-1 (MCP-1) is a potent chemoattractant specific for monocytes. The aim of the present study was to examine whether MCP-1 messenger RNA (mRNA) is expressed in ischemic brain tissue after MCAO. METHODS: The expression of MCP-1 mRNA in the ischemic cortex was first identified by means of a sensitive reverse transcription and polymerase chain reaction technique. The time course of expression of MCP-1 mRNA in the ischemic and nonischemic cerebral cortex after both permanent MCAO and temporary MCAO (160 minutes) with reperfusion was then examined by means of Northern blot analysis. RESULTS: Almost no expression of MCP-1 mRNA was found in the sham-operated or nonischemic (contralateral) cortex. A significant increase in MCP-1 mRNA expression in the ischemic cortex was observed after either permanent or temporary MCAO. MCP-1 mRNA was elevated at 6 hours (4.4-fold increase over sham; n = 4), reached its highest expression from 12 hours to 2 days (22.7-fold at the peak level; P < .01), and remained elevated up to 5 days (5.6-fold; P < .01) after permanent MCAO. The profile of MCP-1 mRNA expression in the ischemic cortex after MCAO with reperfusion was similar to that of permanent MCAO except that MCP-1 mRNA was increased earlier (ie, 12.5-fold increase at 3 hours; n = 4; P < .01). Also, MCP-1 mRNA expression in the ischemic cortex after permanent MCAO was significantly greater in hypertensive rats than in two normotensive rats (n = 4; P < .05). CONCLUSIONS: The demonstration of induced MCP-1 mRNA expression early after focal ischemia suggests that MCP-1 may represent a locally expressed monocyte chemoattractant that plays an important role in monocyte infiltration into ischemic tissue and therefore may contribute to the tissue injury in ischemic stroke. Further studies must concentrate on identifying the induced expression of MCP-1 and its cellular localization in the ischemic brain when the appropriate antibodies become available.

Animals↗

PubMed1995

Demonstration of increased endothelial-leukocyte adhesion molecule-1 mRNA expression in rat ischemic cortex.

BACKGROUND AND PURPOSE: Leukocyte infiltration from circulating blood into ischemic brain tissue contributes significantly to ischemic injury. The role of adhesion molecules in leukocyte attachment and infiltration in ischemic tissue has been emphasized. The aim of the present study was to evaluate whether endothelial-leukocyte adhesion molecule-1 (ELAM-1 or E-selectin) mRNA expression is upregulated in focal brain ischemia. METHODS: Northern blot analysis with the use of poly(A) RNA isolated from the ischemic and nonischemic rat cortex at 2 and 12 hours after permanent occlusion of the middle cerebral artery (PMCAO) was used to examine ELAM-1 mRNA expression. The temporal expression profile of ELAM-1 mRNA in the ischemic cortex was further evaluated with the use of a quantitative reverse transcription and polymerase chain reaction technique. RESULTS: A very low level of ELAM-1 mRNA was detected in the sham-operated cortex or in the nonischemic cortex. The expression of ELAM-1 mRNA in the focal ischemic cortex was significantly induced by PMCAO, reaching a peak level at 12 hours (6.9-fold increase compared with sham surgery cortical samples, P < .01) and remained elevated for up to 2 days (3.3-fold increase, P < .01) after PMCAO. CONCLUSIONS: The demonstration of upregulated ELAM-1 mRNA expression after focal stroke suggests that ELAM-1 may play an important role in leukocyte infiltration into the ischemic brain and that ELAM-1 may provide a potential therapeutic target in ischemic stroke. However, the demonstration of translated ELAM-1 and its cellular localization in the ischemic tissue is required when specific antibodies become available.

Animals↗

PubMed1995

Antagonism of neutrophil adherence in the deteriorating stroke model in rabbits.

Adhesion of leukocytes to the endothelium can occur in a few hours after the onset of ischemia, and the actions of leukocytes have been suggested to aggravate reperfusion injury. Adhesion is a prerequisite for the harmful leukocyte actions. Rapid mediation of leukocyte adhesion and aggravation of reperfusion injury can occur through production of platelet-activating factor (PAF). The authors hypothesized that prevention of leukocyte adhesion during ischemia reperfusion would have beneficial effects and that these effects might be enhanced by a PAF antagonist. To test this hypothesis, rabbits were anesthetized with pentobarbital and subjected to severe spinal cord ischemia (25 minutes) followed by 30 minutes of reperfusion, at which time either vehicle, antibody against the CD11/CD18 (anti-CD) leukocyte adhesion molecule (1 mg/kg), or the anti-CD and PAF antagonist, WEB 2086 (3 mg/kg), was administered intravenously and the animals were monitored for 6.5 hours. Using a score from 0 to 5, recovery of motor function was improved at 5.5 hours by the CD antibody (2.0 +/- 0.5 versus 0.4 +/- 0.2 in the six animals in the vehicle group, p < 0.05). No further improvement was induced by WEB 2086 in the six anti-CD treated animals (1.6 +/- 0.7). Spinal cord blood flow (laser Doppler flowmetry) at 6 hours was at the preischemic level in the control animals (-7% +/- 20%), but clearly increased in the anti-CD group (+73% +/- 29%, p < 0.5). The severity of blood-brain barrier damage in the spinal cord gray matter was decreased by the treatments. Extravasation of intravenously injected Evans blue albumin (EBA), measured by detection of EBA fluorescence, was reduced by approximately 50% in both treated groups (p < 0.05). The number of morphologically normal motor neurons in the lumbar anterior horns of the infarcted spinal cord showed protection in the seven animals in the anti-CD treated group at 6.5 hours: 12.7 +/- 1.7 versus 5.3 +/- 1.6 (vehicle), p < 0.05 without an additional effect by PAF antagonist 12.2 +/- 2.6 (anti-CD + WEB 2086). Our results suggest that ultraacute treatment of reperfusion injury based on special inhibition of leukocyte effects may be beneficial. Platelet-activating factor antagonism failed to enhance this therapeutic effect, which may suggest dependency on a common mechanism.

Animals↗

PubMed1995

Carvedilol, a new beta-adrenoreceptor blocker, vasodilator and free-radical scavenger, exerts an anti-shock and endothelial protective effect in rat splanchnic ischemia and reperfusion.

Splanchnic artery occlusion (SAO) followed by reperfusion results in circulatory shock in which oxygen-derived free radicals play an important role. Carvedilol, a novel beta adrenoceptor antagonist and a vasodilator, has been recently shown to exert potent antioxidant effects in multiple cell model systems. In the present experiment, we investigated the effect of carvedilol on SAO shock. Pentobarbital-anesthetized rats were subjected to 60 min of SAO followed by 120 min of reperfusion. Administration of 1 mg/kg carvedilol 10 min before reperfusion prolonged survival time (P < .05) and attenuated the increases in tissue myeloperoxidase activities (P < .01) and hematocrits (P < .001). Moreover, carvedilol significantly preserved superior mesenteric artery endothelial function (P < .01). Similar protection was seen in SAO shock rats treated with the superoxide free-radical scavenger superoxide dismutase. Except for a moderate attenuation of an increase in hematocrits, protective effects were not seen in SAO shock rats treated with the prototypic beta blocker propranolol. These results indicate that in murine SAO shock, carvedilol affords significant protection, which may be achieved through maintenance of tissue blood perfusion, quenching of oxygen free radicals, preservation of vascular endothelial function, and inhibition of neutrophil-endothelial interaction and its resultant increased microvascular permeability.

Adrenergic beta-Antagonists↗

PubMed1995

Direct sequencing of DNA isolated from mRNA differential display.

A recently developed mRNA differential display technique has a potential power for identifying genes that are differentially expressed in a variety of in vitro and in vivo systems. One critical feature of this technique is to display most of the mRNA population on a sequencing gel after polymerase chain reaction using a 5' decamer and a 3' T12MN anchored primer. However, these primers are too small to be successfully used as a sequencing primer using the classical sequencing protocol. In the present report we described the application of an extended primer set for the re-amplification after mRNA differential display, which renders the amplified DNA suitable for direct sequencing using either of these extended oligonucleotides as a primer without further subcloning. This improved technique will greatly save the time, cost and labor-intensive work for the discovery of genes using mRNA differential display.

Animals↗

PubMed1995

Use of differential display to identify differentially expressed mRNAs induced by rat carotid artery balloon angioplasty.

BACKGROUND: We have used differential display technology in an animal model of arterial restenosis to study the molecular mechanisms of neointima formation. EXPERIMENTAL DESIGN: Balloon angioplasty of the rat common carotid artery was performed, and tissues were examined from naive animals (control) and from animals that had undergone angioplasty 6 hours, 3 days, and 14 days earlier. Total RNA was isolated, and differential display was performed to identify mRNA transcripts whose expression is modulated in a temporal fashion as a consequence of balloon angioplasty. RESULTS: Using total RNA isolated from vessels excised from naive rats and those from rats that underwent angioplasty up to 14 days earlier, we describe two differentially regulated transcripts by differential display and verify the expression pattern of these same transcripts by Northern analysis. DNA sequence analysis has identified one of these angioplasty-induced transcripts as a novel sequence and the other as the tryptophan hydroxylase and protein kinase C regulatory protein 14-3-3 gamma. CONCLUSIONS: In this study, we describe the in vivo application of the differential display technique in a rat carotid artery angioplasty model to identify mRNA transcripts whose expression is modulated selectively in vessels undergoing neointima formation. Use of this technique in animal models of disease should facilitate our understanding of gene expression patterns in pathogenesis and may serve as a reliable technique to "fingerprint" disease processes.

14-3-3 Proteins↗

PubMed1995

Carvedilol, a new vasodilating beta-adrenoceptor blocker, inhibits oxidation of low-density lipoproteins by vascular smooth muscle cells and prevents leukocyte adhesion to smooth muscle cells.

The present study was undertaken to assess the effect of carvedilol, a new vasodilating beta-adrenoceptor blocker with antioxidant activity, on the oxidation of low-density lipoproteins (LDL) by rat aortic smooth muscle cells (RASMC). LDL oxidation was assessed as thiobarbituric acid reactive substances (TBARS) formation and increase in electrophoretic mobility. Oxidized (ox) LDL-induced cytotoxicity was assessed as lactate dehydrogenase release (LDH) from cells and ox-LDL-enhanced adhesiveness of the RASMC for leukocytes was also determined. Carvedilol inhibited TBARS formation and LDH release from RASMC with IC50 values of 1.74 and 1.62 microM, respectively. Under the same conditions, the IC50 values of probucol and nicardipine were 2.33 and 5.60 microM, respectively, for inhibition of TBARS and 5.16 and 12.10 microM, respectively, for inhibition of LDH release; propranolol, atenolol, pindolol and labetalol, at concentrations up to 100 microM, had virtually no effect on either variable. RASMC-dependent ox-LDL stimulated the adhesive properties of RASMC for both monocytes and neutrophils in a concentration- and time-dependent manner, which were prevented when the RASMC were treated with carvedilol (IC50 2.07 microM for monocytes and 1.12 microM for neutrophils), whereas other beta blockers, at concentrations up to 30 microM, had only mild effects. The monoclonal antirat intercellular adhesion molecule-1 antibody partially inhibited ox-LDL-induced adhesion of RASMC for monocytes and neutrophils. Northern analysis demonstrated that ox-LDL induced intracellular adhesion molecule-1 messenger RNA expression on RASMC, which was inhibited by carvedilol and probucol via inhibition of LDL oxidation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗

PubMed1995

Temporal expression of ECE-1, ET-1, ET-3, ETA, and ETB receptor mRNAs after balloon angioplasty in the rat.

The temporal expressions of endothelin-converting enzyme-1 (ECE-1), preproendothelin-1 (preproET-1), preproET-3, and ETA, ETB receptor mRNAs were studied in rat carotid artery after balloon angioplasty using quantitative reverse transcription and the polymerase chain reaction (RT-PCR). The expression profile of these messages revealed that the increases of ECE-1 mRNA preceded those of preproET-1 and preproET-3. A significant increase in ECE-1 mRNA was observed at 6 h (1.8-fold, p < 0.01) and 24 h (1.7-fold, p < 0.01) after angioplasty, whereas a significant increase in preproET-1 mRNA levels was not observed until day 3 (1.9-fold, p < 0.05) and day 7 (2.1-fold, p < 0.05). A similar delayed increase in preproET-3 mRNA was observed at day 7 (2.8-fold, p < 0.05) and day 14 (2.6-fold, p < 0.05) after angioplasty. The levels of ETA receptor mRNA were elevated 29.3-fold (p < 0.001) and 24.3-fold (p < 0.01) at days 3 and 7 after angioplasty, respectively. The increase in ETB receptor mRNA occurred slightly earlier than that of ETA receptor, showing a 15.1-fold increase at day 1 (p < 0.001) and a 11.3-fold increase at day 3 (p < 0.01) after angioplasty. The data suggest that ECE-1, ET-1, ET-3, and ETA and ETB receptors play an active role in the pathogenesis of neointima formation.

Angioplasty, Balloon↗

PubMed1995

The endothelin receptor antagonist SB 217242 reduces cerebral focal ischemic brain injury.

Previously, we demonstrated that cerebral focal ischemic tissue exhibits a significant increase in immunoreactive endothelin (ET). Because increased ET might exacerbate the consequences of cerebral ischemia, we evaluated the effects of the orally active ETA/B receptor antagonist SB 217242 on middle cerebral artery occlusion (MCAO) in the spontaneously hypertensive rat (SHR). SHRs were treated b.i.d. with vehicle or with 3 or 15 mg/kg SB 217242 p.o. for 7 days. Permanent MCAO was performed on day 7 and animals were sacrificed on day 8. Forebrains were stained and the extent of cerebral (i.e., cortical) infarction was determined using image analysis. Hemispheric swelling (%), hemispheric infarct (%), and infarct volume (mm3) were quantitated for each animal. SB 217242 treatment produced a significant decrease in ischemic brain injury. Hemispheric infarction and infarct volume were reduced after the 15 mg/kg treatment (12.0 +/- 1.1% and 69 +/- 6 mm3) compared to vehicle (17.3 +/- 1.5% and 99 +/- 8 mm3) (p < 0.05). No significant effects on hemispheric swelling were observed. This is the first demonstration of an ET receptor antagonist exhibiting efficacy in cerebral focal ischemia. The fact that a 30% reduction in ischemic brain injury can be demonstrated after oral administration of SB 217242 suggests that ET antagonists may be of therapeutic utility in focal stroke.

Animals↗

PubMed1994

Carvedilol, a new antihypertensive drug with unique antioxidant activity: potential role in cerebroprotection.

The antioxidant activities of carvedilol have been demonstrated in a wide variety of test systems, including (i) physicochemical (EPR studies), (ii) biochemical (measurement of lipid peroxidation and endogenous antioxidant depletion), (iii) cellular, and (iv) in vivo. The antioxidant activity of carvedilol clearly emanates from the carbazole moiety which is unique to carvedilol. The antioxidant activity resides equally in both of the enantiomers of carvedilol, as well as in some of its metabolites which are devoid of either the alpha 1-adrenoceptor blocking activity or beta-adrenoceptor blocking activity. This novel antioxidant property of carvedilol may account, at least in part, for its cerebroprotection. The data discussed in this article suggest that carvedilol may not only provide effective and safe antihypertensive therapy and therefore reduce a major risk factor for stroke, but will also be better able to provide additional benefits to patients by protecting against oxygen free radicals generated during cerebral ischemia and stroke.

Animals↗

PubMed1994

SB 211475, a metabolite of carvedilol, a novel antihypertensive agent, is a potent antioxidant.

The antioxidant effects of SB 211475, a metabolite of carvedilol, a novel antihypertensive agent, were studied and compared with carvedilol and other antioxidants such as U78517F, U74500A and probucol. SB 211475 inhibited Fe(2+)-vitamin C-initiated lipid peroxidation, assessed as thiobarbituric acid reactive substance, in brain-homogenate with an IC50 of 0.28 microM. Under the same conditions, the IC50s of probucol, carvedilol, U74500A and U78517F were 50, 8.1, 0.71 and 0.16 microM, respectively. SB 211475 inhibited oxidation of human low density lipoprotein by mouse macrophages with an IC50 of 0.043 microM. In the same model, the IC50s of carvedilol, U78517F and probucol were 3.8, 0.15, and 0.80 microM, respectively. SB 211475 protected cultured bovine pulmonary artery endothelial cells against hydroxyl radical-initiated lipid peroxidation (IC50 = 0.15 microM) and cell damage (lactate dehydrogenase release, IC50 = 0.16 microM), and promoted cell survival with an EC50 of 0.13 microM. SB 211475 also protected endothelial cells against xanthine/xanthine oxidase-initiated cytotoxicity and protected rat cerebellar neurons from hydroxyl radical-mediated cell death (EC50 = 0.19 microM). Moreover, SB 211475 inhibited superoxide (O2-) release from human neutrophils stimulated by phorbol myristate acetate. These observations indicate that SB 211475 is a potent antioxidant and may potentially contribute to the therapeutic effects of carvedilol in vivo.

Adenosine Diphosphate↗

PubMed1994

Osteopontin-stimulated vascular smooth muscle cell migration is mediated by beta 3 integrin.

Osteopontin (OPN), a 41-kDa phosphorylated glycoprotein, has been detected in rat aorta and carotid arteries, and expression of its mRNA in blood vessels is strongly increased in response to vascular injury. To investigate the potential role of OPN in vascular pathophysiology, we studied the effect of rat OPN on aortic smooth muscle cell migration and proliferation in vitro. OPN enhanced the migration of rat smooth muscle cells in a time- and concentration-dependent manner with an EC50 value of 46 +/- 11 nmol/liter (n = 5). The maximal increase in cell migration by OPN was 29-fold over basal levels. OPN-induced smooth muscle cell migration was inhibited in a concentration-dependent manner by the monoclonal antibody F11, which recognizes the rat integrin subunit beta 3. In contrast, polyclonal antiserum recognizing the rat integrin beta 1 subunit did not inhibit smooth muscle cell migration in response to OPN, but did block fibronectin-promoted migration. Moreover, OPN-induced smooth muscle cell migration was dependent on the presence of extracellular divalent cations and was significantly inhibited by anti-OPN antibodies. OPN did not stimulate [3H]thymidine incorporation into cultured smooth muscle cells, indicating that it selectively enhanced migration. In view of the pathological significance of arterial smooth muscle cell migration in the formation of intimal thickening, our results suggest that smooth muscle cell recognition of OPN, probably through the vitronectin receptor, alpha v beta 3, could play a role in the cells' response to vascular injury and especially neointima formation.

Animals↗

PubMed1994

Upregulation of intercellular adhesion molecule 1 (ICAM-1) on brain microvascular endothelial cells in rat ischemic cortex.

The expression of intercellular adhesion molecule 1 (ICAM-1) was studied in rat focal ischemic cortex. A significant increase in ICAM-1 mRNA expression in the ischemic cortex over levels in contralateral (nonischemic) site was observed by means of Northern blot analysis following either permanent or temporary occlusion with reperfusion of the middle cerebral artery (PMCAO or MCAO with reperfusion) in spontaneously hypertensive rats. In the ischemic cortex, levels of ICAM-1 mRNA increased significantly at 3 h (2.6-fold, n = 3, P < 0.05), peaked at 6 to 12 h (6.0-fold, P < 0.01) and remained elevated up to 5 days (2.5-fold, P < 0.05) after PMCAO. The profile of ICAM-1 mRNA expression in the ischemic cortex following MCAO with reperfusion was similar to that following PMCAO, except that ICAM-1 mRNA was significantly increased as early as 1 h (6.3-fold, n = 3, P < 0.05) and then gradually reached a peak at 12 h (12-fold, P < 0.01) after reperfusion. ICAM-1 mRNA expression in ischemic cortex following PMCAO was significantly greater in hypertensive rats than in two normotensive rat strains. Immunostaining using anti-ICAM-1 antibodies indicated that upregulated ICAM-1 expression was localized to endothelial cells of intraparenchymal blood vessels in the ischemic but not contralateral cortex. The data suggest that an upregulation of ICAM-1 mRNA and protein on brain capillary endothelium may play an important role in leukocyte migration into ischemic brain tissue.

Animals↗

PubMed1994

Reperfusion following focal stroke hastens inflammation and resolution of ischemic injured tissue.

Previously, we described cellular changes following Permanent Middle Cerebral Artery Occlusion (PMCAO) in spontaneously hypertensive rats. Ischemic changes following PMCAO included a time-related focal pan necrosis, inflammatory cell infiltration, gliosis, and eventual loss of necrotic tissue post PMCAO. We have now characterized changes which occur after Temporary Middle Cerebral Artery Occlusion (TMCAO; 80 or 160 min) followed by reperfusion and compared these changes to those which occur following PMCAO. TMCAO with reperfusion results in cortical infarcts which vary in size in an occlusion-time-dependent manner. After 1 h of reperfusion, ischemic changes were observed histologically, including microhemorrhages and the beginning of a slight inflammatory infiltration in and around the meningeal vasculature. This infiltrate consisted primarily of neutrophils, which by 6 h of reperfusion was significant with infiltration from deep blood vessels into brain tissue, including the presence of some monocytes adhering within blood vessels. Neutrophil infiltration occurred sooner and to a greater extent in reperfused tissues than in permanently occluded tissues, where it only began at 12 h post PMCAO. As occurred following PMCAO, increased Glial Fibrillary Acidic Protein (GFAP) immunoreactivity indicating astrogliosis was first observed at 12 h postTMCAO. Over 1-3 days of reperfusion, a heavy macrophage infiltrate was observed in the reperfused tissues in addition to a continued influx of neutrophils. Following 5 days of reperfusion, the lesion was completely replaced with inflammatory cells, of which macrophages predominated. Unlike PMCAO, which resulted in focal spots of neutrophil accumulation, neutrophils were more distributed throughout the infarcted cortex following TMCAO.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

Endothelin levels increase in rat focal and global ischemia.

Endothelin-1, a peptide exhibiting extremely potent cerebral vasoactive properties, is elevated in the cerebrospinal fluid after hemorrhagic stroke and implicated in cerebral vasospasm. The purpose of this study was to determine changes in endothelin in ischemic rat brain by assaying endothelin tissue and extracellular levels. Immunoreactive endothelin levels in ischemic brain tissue following permanent or transient focal ischemia produced by middle cerebral artery occlusion was determined. In addition, endothelin levels were assayed in striatal extracellular fluid collected by microdialysis before, during, and after global ischemia produced by two-vessel occlusion combined with hypotension. Twenty-four hours after the onset of permanent middle cerebral artery occlusion, the ischemic cortex level (0.58 +/- 0.27 fmol/mg protein) of immunoreactive endothelin was significantly (p < 0.05) increased, by 100%, over that in the nonischemic cortex (0.29 +/- 0.13 fmol/mg protein). Transient artery occlusion for 80 min with reperfusion for 24 h also resulted in a similar significant (p < 0.05) increase, 78%, in immunoreactive endothelin in the ischemic zone. Global forebrain ischemia significantly (p < 0.05) increased the level of immunoreactive endothelin collected in striatal microdialysis perfusate, from a basal level of 14.6 +/- 6.7 to 26.5 +/- 7.7 and 26.2 +/- 7.4 amol/microliters (i.e. 82 and 79%). These changes reflect the relative picomolar extracellular concentration increases during ischemia and following reperfusion, respectively. This is the first demonstration of elevated levels of endothelin in focal ischemic tissue and in the extracellular fluid in global ischemia and suggests a role of the peptide in ischemic and postischemic derangements of cerebral vascular function and tissue injury.

Animals↗