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Biomedical subjects

A M Lefer

Publications and source records attributed to A M Lefer.

At least 55 records · Page 3Linked to original sources
PubMed1998

Mechanisms of cardioprotection by peroxynitrite in myocardial ischemia and reperfusion injury.

Peroxynitrite (ONOO-), an intermediate formed from the equimolar interaction of nitric oxide (NO) and superoxide, is thought to be an important mediator of tissue injury in myocardial ischemia-reperfusion. However, physiologically relevant (i.e., maximally achievable) concentrations of ONOO- significantly decreased neutrophil-endothelium interactions in the rat mesentery. We therefore examined the dose-response relationship of infusion of different concentrations of ONOO- in a feline model of myocardial ischemia-reperfusion and provide data on the cellular mechanisms responsible for these observed effects. Cats subjected to 90 min of ischemia followed by 270 min of reperfusion were infused with different concentrations of ONOO- 10 min before reperfusion and continuing throughout reperfusion. We observed that infusion of 2 microM ONOO- provided significant cardioprotection, whereas either 0.2 or 20 microM ONOO- did not protect. ONOO- at 2 microM also preserved coronary endothelial function, decreased P-selectin expression, and attenuated polymorphonuclear leukocyte (PMN) adherence to the vascular endothelium. ONOO- did not exert its cardioprotective effects by acting as a direct NO donor in solution. However, in vitro, ONOO- can react with glutathione to form S-nitrosoglutathione, which can act as an NO carrier and exert beneficial effects. Thus only maximally achievable concentrations of ONOO- exert significant cardioprotective effects, in part by decreasing surface expression of P-selectin and decreasing PMN-endothelium interactions.

Animals↗
PubMed1998

Time course of endothelial-neutrophil interaction in splanchnic artery ischemia-reperfusion.

Splanchnic artery occlusion and reperfusion (SAO/R) results in a severe form of circulatory shock that has a high mortality rate. To examine the time course of the early events involved in SAO/R, occlusion of the superior mesenteric artery (SMA) and the celiac artery (120 min) were followed by reperfusion periods of 0, 2.5, 5, 20, 30, 60, or 120 min. Relaxation of isolated SMA vascular rings to the endothelium-dependent vasodilator ACh was unimpaired following 120 min of ischemia (86 +/- 5%); however, significant (P < 0.01) reductions in endothelium-dependent vasorelaxation were observed following 2.5 min (53 +/- 6%) of reperfusion with severe dysfunction (P < 0.001) observed at 20 min (29 +/- 4%). Neutrophil adherence to the endothelium increased as a function of reperfusion time with a 2.3-fold increase observed at 20 min (P < 0.01) and a 3.4-fold increase observed at 120 min (P < 0.001). Intestinal myeloperoxidase activity was significantly increased 30 min after reperfusion (P < 0.05), whereas surface expression of P-selectin progressively increased at 5 (P < 0.05) and 30 min (P < 0.001) postreperfusion. These findings demonstrate that endothelial dysfunction is a very early event in the pathophysiology of SAO/R, subsequently resulting in increased surface expression of P-selectin and the adherence of neutrophils to the endothelium that leads to neutrophil accumulation in the splanchnic viscera.

Animals↗
PubMed1998

Leukocyte-endothelium interaction during the early stages of hypercholesterolemia in the rabbit: role of P-selectin, ICAM-1, and VCAM-1.

The early effects of hypercholesterolemia on leukocyte-endothelium interaction were studied in vivo in the rabbit mesenteric microcirculation. Rabbits fed a 0.5% high-cholesterol (HC) diet showed elevated plasma cholesterol levels during the 1 to 2 weeks of HC feeding (P<0.001 versus control diet-fed rabbits). Intravital microscopy of mesenteric venules revealed that leukocyte rolling had increased 10-fold (P<0.001 versus control-fed group) at the end of the first week of the HC diet, which was sustained after 2 weeks of HC feeding (P<0.001 versus control-fed rabbits). Firm adherence of leukocytes to the endothelium was moderately increased after a 1-week period of hypercholesterolemia (P<0.05) but increased by 12-fold at 2 weeks (P<0.001 versus control diet-fed and P<0.01 versus 1-week HC-fed rabbits). Upregulation of the endothelial cell adhesion molecules P-selectin, intercellular adhesion molecule-1, and vascular cell adhesion molecule-1 was observed immunohistochemically on the intestinal microvascular endothelium of HC-fed rabbits. P-selectin was maximally expressed within the first week of the HC diet and remained elevated during the second week of cholesterol feeding (P<0.01 versus control). In contrast, intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 were moderately upregulated at 1 week but were highly expressed after 2 weeks of the HC diet (P<0.05 and P<0.001 versus control, respectively). Basal release of NO from both mesenteric microvascular and aortic endothelium in cholesterol-fed rabbits was progressively reduced after 1 (P<0.05) and 2 (P<0.01) weeks. Our data suggest that enhanced leukocyte-endothelium interaction occurs in vivo in the rabbit microcirculation during the first 2 weeks of hypercholesterolemia. This phenomenon is associated with impaired basal NO release and progressive endothelial surface expression of endothelial cell adhesion molecules (ie, P-selectin, intercellular adhesion molecule-1, and vascular cell adhesion molecule-1) in the microvasculature.

Animals↗
PubMed1998

L-arginine attenuates endothelial dysfunction and prolongs survival in rats subjected to traumatic shock.

We investigated the effects of L-arginine administration in a rat model of traumatic shock. Pentobarbital-anesthetized rats subjected to drum trauma developed a severe shock condition characterized by marked hypotension to 55-70 mmHg, a survival time of only 90 +/- 21 min, and significant increases in ileal myeloperoxidase (MPO) activity (P < 0.01). In addition, superior mesenteric artery (SMA) rings isolated from rats subjected to traumatic shock relaxed to the endothelium-dependent vasodilator acetylcholine significantly less than rings isolated from control rats (p < 0.01). Administration of L-arginine (30 mg/kg bolus + 10 mg/kg/hr, i.v.) 10 min following trauma prolonged survival time to 213 +/- 33 min (p < 0.05) and attenuated ileal MPO activity (p < 0.01) indicative of reduced neutrophil infiltration. Furthermore, SMA endothelial function was significantly (p < 0.01) preserved in L-arginine treated traumatic shock rats. These results indicate that L-arginine plays a key role in the endothelial dysfunction associated with traumatic shock and affords significant protective effects which may be manifested by an inhibition of leukocyte-endothelial cell interactions.

Animals↗
PubMed1997

Peroxynitrite reduces myocardial infarct size and preserves coronary endothelium after ischemia and reperfusion in cats.

BACKGROUND: Peroxynitrite (ONOO-) is purported to exert cytotoxic effects at high doses. However, physiologically relevant concentrations of ONOO- inhibit polymorphonuclear neutrophil (PMN) adhesion to the endothelium and attenuate PMN-mediated contractile dysfunction in isolated perfused rat hearts. We are unaware of any reports in vivo showing effects of peroxynitrite in myocardial ischemia and reperfusion (MI/R). Thus, the purpose of this study was to examine the in vivo effects of a physiologically relevant concentration of ONOO- (1 micromol/L) in a feline model of MI/R injury. METHODS AND RESULTS: ONOO- (1 micromol/L) or its vehicle (0.9% NaCl at pH 8.4) was infused intraventricularly, starting 10 minutes before reperfusion in cats subjected to 90 minutes of myocardial ischemia and 4.5 hours of reperfusion. ONOO(-)-treated cats demonstrated marked attenuation of cardiac necrosis after MI/R compared with cats receiving only vehicle (P<.001). Moreover, vasorelaxation of ischemic-reperfused left anterior descending (LAD) coronary artery rings in response to the endothelium-dependent dilators acetylcholine and A23187 was greater in rings isolated from ONOO(-)-treated MI/R cats compared with MI/R cats receiving only vehicle, indicating that postreperfusion coronary vascular endothelial function was preserved by ONOO-. ONOO- also significantly reduced adherence of neutrophils to the ischemic-reperfused LAD coronary endothelium. Immunohistochemical localization of P-selectin was also significantly attenuated in hearts from ONOO(-)-infused MI/R cats. CONCLUSIONS: These data suggest that physiologically relevant concentrations of ONOO- exert significant cardioprotective and vasculoprotective effects in MI/R in cats, at least partially by attenuating PMN-endothelium interactions.

Animals↗
PubMed1997

Cardioprotective effect of interleukin-10 in murine myocardial ischemia-reperfusion.

We investigated the cardioprotective effects of rat interleukin-10 in a murine model of myocardial ischemia-reperfusion (20 min ischemia, 24 h reperfusion). Interleukin-10 (100 microg/rat) administered 15 min prior to reperfusion, significantly (P < 0.01) attenuated myocardial injury compared to rats receiving only 0.9% saline as a vehicle, as indicated by a reduced loss of myocardial creatine kinase from the ischemic-reperfused myocardium. Cardiac myeloperoxidase activity was also significantly (P < 0.01) attenuated by interleukin-10 within the ischemic-reperfused region compared to vehicle treated rats. To further investigate the mechanism of interleukin-10 we observed the in vitro adherence of neutrophil to rat vascular endothelium. Interleukin-10 treatment significantly (P < 0.05) attenuated neutrophil adherence to rat superior mesenteric artery endothelium stimulated with interleukin-1beta. Thus, interleukin-10 demonstrated significant cardioprotective effects as evidenced by a decrease in myocardial creatine kinase loss as well as an inhibition of neutrophil accumulation within the myocardium. It appears as though interleukin-10 mediates its effects, at least in part, by inhibiting leukocyte-endothelial interactions.

Animals↗
PubMed1997

Lipoxin A4 stable analogs inhibit leukocyte rolling and adherence in the rat mesenteric microvasculature: role of P-selectin.

Three different stable lipoxin A4 (LXA4) analogs (i.e., 16-phenoxy-LXA4-Me, 15-cyclohexyl-LXA4-Me, and 15-R/S-methyl-LXA4-Me) were studied for their ability to modulate leukocyte-endothelial cell interactions in the rat mesenteric microvasculature. Superfusion of the rat mesentery with 50 micromol/liter NG-nitro-L-arginine methyl ester (L-NAME) caused a significant, time-dependent increase in leukocyte rolling (56 +/- 8 cells/min; P < 0.01 vs. control) and leukocyte adherence (12.5 +/- 1. 2 cells/100 micron length of venule; P < 0.01 vs. control) after 120 min of superfusion. Concomitant superfusion of the rat mesentery with 10 nmol/liter of each of three lipoxin analogs consistently and markedly attenuated L-NAME-induced leukocyte rolling to 10 +/- 4 (P < 0.01), 4 +/- 1 (P < 0.01), and 32 +/- 7 (P < 0.05) cells/min, and adherence to 4 +/- 0.8 (P < 0.01), 1.1 +/- 0.4 (P < 0.01), and 7 +/- 0.7 (P < 0.05) cells/100 micron length of venule (16-phenoxy-LXA4-Me, 15-cyclohexyl-LXA4-Me, and 15-R/S- methyl-LXA4-Me, respectively). No alterations of systemic blood pressure or mesenteric venular shear rates were observed in any group. Immunohistochemical up-regulation of P-selectin expression on intestinal venular endothelium was significantly increased (P < 0.01) after exposure to L-NAME, and this was significantly attenuated by these lipoxin analogs (P < 0.01). Thus, in vivo superfusion of the rat mesentery with stable lipoxin analogs at 10 nmol/liter reduces L-NAME-induced leukocyte rolling and adherence in the mesenteric rat microvasculature by attenuating P-selectin expression. This anti-inflammatory mechanism may represent a novel and potent regulatory action of lipoxins on the immune system.

Animals↗
PubMed1997

Peroxynitrite inhibits leukocyte-endothelial cell interactions and protects against ischemia-reperfusion injury in rats.

Peroxynitrite (ONOO-) anion, formed by the interaction of superoxide with nitric oxide (NO), has previously been implicated as a cytotoxic agent. However, the effects of this free radical species on neutrophil (PMN)-endothelial cell interactions is largely unknown. We investigated the direct actions of ONOO- on PMN adhesion to endothelial cells in vitro and in vivo, as well as the effects of ONOO- on PMN-mediated myocardial ischemia-reperfusion injury. In vitro, peroxynitrite (100-1,000 nM) inhibited the adhesion of rat PMNs to the endothelium of isolated thrombin- or H2O2-stimulated rat mesenteric artery (P < 0.01 vs. thrombin or H2O2 alone). In vivo, in the rat mesentery, thrombin (0.5 U/ml) or N(G)-nitro-L-arginine-methyl ester (50 microM) significantly increased venular leukocyte rolling and adherence, which were also significantly (P < 0.01) attenuated by ONOO (800 nM) accompanied by reduced P-selectin expression on the endothelial cell surface. Isolated perfused rat hearts were subjected to global ischemia and reperfusion with rat PMNs (10(8) cells), which resulted in profound cardiac depression (i.e., a marked reduction in left ventricular developed pressure and maximal rate of development of left ventricular pressure). Infusion of ONOO- reversed the myocardial contractile dysfunction of ischemic-reperfused rat hearts to near baseline levels, and markedly attenuated the accumulation of PMNs in the postischemic heart. The present study provides strong evidence that nanomolar concentrations of ONOO- both inhibit leukocyte-endothelial cell interactions and exert cytoprotective effects in myocardial ischemia-reperfusion injury. Furthermore, our results suggest that the inhibition of P-selectin expression by peroxynitrite is a key mechanism of the modulatory actions of ONOO- on leukocyte-endothelial cell interactions.

Animals↗
PubMed1997

P-selectin is up-regulated in vital organs during murine traumatic shock.

Murine traumatic shock is associated with increased adherence of neutrophils to the vascular endothelium resulting in neutrophil infiltration and tissue damage. We examined the effects of trauma on the expression of the adhesion molecule P-selectin in several vital organs (i.e., heart, lungs, liver, kidneys, and small intestine) 2 h after induction of Noble-Collip drum trauma in anesthetized rats. Total RNA was extracted from these organs and P-selectin mRNA was quantified by RNase protection assays. P-selectin mRNA was significantly increased over control nontraumatized, anesthetized rats in all vital organs (P<0.05 or less), with the largest increase occurring in the lung (P<0.01). Immunohistochemical analysis showed increased expression of P-selectin protein in postcapillary venules of all vital organs after trauma. To further investigate the possible mechanisms of increased P-selectin mRNA transcription promoter activity during trauma, we quantified binding of proteins from nuclear extracts to the kappaB site (-218GGGGGTGACCC[-207]) of the P-selectin gene by electrophoretic mobility shift assay. We confirmed the results of NF-kappaB binding by demonstrating increases in p50 and p52, as well as decreases in IkappaB in cytoplasmic and nuclear extracts from the lungs of trauma rats by Western blotting. Increased activity of the transcription factor, nuclear factor kappaB (NF-kappaB), occurred in all vital organs of the trauma rats compared to sham-operated controls. Our findings suggest that severe trauma results in up-regulation of P-selectin at the transcriptional level, which is partly controlled by an NF-kappaB-responsive element in the region of the P-selectin promoter. This increased activation of NF-kappB binding may contribute to the widespread increases in P-selectin expression observed in several vital organs 2 h after trauma, which in turn may play a key role in the pathogenesis of traumatic shock.

Animals↗
PubMed1997

Beneficial effects of C1 esterase inhibitor in murine traumatic shock.

Activation of the complement system is an integral part of the initiation and maintenance of the inflammatory process such as that occurring in traumatic shock, and is considered responsible for much of the trauma-induced microvascular injury. We investigated the effects of early complement blockade induced by a C1 esterase inhibitor (C1 INH) in a rat model of traumatic shock. Pentobarbital-anesthetized rats subjected to Noble-Collip drum trauma developed a shock state characterized by marked hypotension and a 83.3% mortality rate with a mean survival time of 157.5 +/- 26 min. Accompanying these effects were significant endothelial dysfunction and elevated intestinal myeloperoxidase activity. Treatment with C1 INH 15 mg/kg administered intravenously 10 min post-trauma, increases survival rate to 66.7% (p < .05), and prolonged survival time to 248 +/- 27 min (p < .05). C1 INH significantly preserved the endothelium-dependent relaxation to acetylcholine and attenuated the increase in myeloperoxidase activity in C1 INH-treated rats compared with untreated trauma rats (p < .05). Our results suggest that complement activation plays an important role in tissue injury associated with trauma, and that its inhibition at an early step in the complement cascade through a C1 esterase inhibitor is beneficial in rats experiencing traumatic shock. The mechanisms of the protective effect of C1 INH involves preservation of vascular endothelial function and diminished neutrophil accumulation leading to reduced neutrophil-mediated tissue injury.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1997

Lysophosphatidylcholine stimulates leukocyte rolling and adherence in rat mesenteric microvasculature.

Synthetic exogenous lysophosphatidylcholine (LPC) was used to induce leukocyte-endothelial cell interaction, utilizing intravital microscopy in the rat mesenteric microvasculature. Superfusion of the rat mesentery with 10 microM LPC significantly and time dependently increased leukocyte rolling and adherence compared with control rats. Moreover, LPC superfusion did not alter systemic blood pressure or mesenteric venular shear rate. Administration of either an anti-P-selectin monoclonal antibody (PB1.3 at 1 mg/kg i.v.) or a nitric oxide (NO) donor (CAS-1609, 10 microM superfusion) markedly attenuated LPC-induced leukocyte rolling and adherence (P < 0.01 from LPC alone). Immunohistochemical localization of P-selectin and intercellular adhesion molecule-1 (ICAM-1) expression on mesenteric venules was significantly increased after exposure to LPC compared with mesenteries superfused with phosphatidylcholine (P < 0.001). Flow cytometric analysis indicated that 10 microM LPC significantly (P < 0.05) increased P-selectin fluorescence on rat platelets. Furthermore, direct measurement of NO release from rat aortic vascular endothelium was significantly (P < 0.05) inhibited by 10 microM LPC. Thus LPC induces in vivo leukocyte rolling and adherence in the mesenteric rat microvasculature by increasing the surface expression of P-selectin and ICAM-1. Because inhibition of endothelial NO release promotes P-selectin expression, LPC-induced rolling and adherence may be mediated via reduced NO release.

Animals↗
PubMed1997

Regulation of P-selectin expression in human endothelial cells by nitric oxide.

P-selectin translocation to the surface of endothelial cells is increased after exposure to the nitric oxide (NO) synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME), resulting in increased endothelial adhesiveness. L-NAME (3 mM) was added to human cultured iliac vein endothelial cells for 1, 2, 4, and 6 h, and P-selectin mRNA expression was quantified by a ribonuclease protection assay. In parallel experiments, the NO donor, SPM-5185 (10 microM), was added to human iliac venous endothelial cells, and P-selectin mRNA expression quantified. P-selectin protein synthesis was quantified by Western blot analysis. L-NAME caused increased expression of P-selection RNA at 2-4 h, whereas D-NAME, the stereoisomer lacking NO synthase-inhibitory activity, had no effect. The stimulatory effect of L-NAME was reversed by addition of 3 mM L-arginine. SPM-5185 decreased P-selectin mRNA over the same time period (P < 0.02). The increased P-selectin mRNA expression induced by L-NAME was paralleled by an increase in P-selectin protein synthesis. The effects of SPM-5185 and L-arginine were also paralleled by decreases in P-selectin protein synthesis and in decreased adherence of human neutrophils to human iliac venous endothelial cells. The peak effect of inhibition of NO synthesis or addition of exogenous NO occurred at 2-4 h. These results suggest a regulatory effect of NO on endothelial P-selectin expression that modulates early leukocyte-endothelial cell interactions to preserve vascular homeostasis.

Arginine↗
PubMed1997

Heparinase III exerts endothelial and cardioprotective effects in feline myocardial ischemia-reperfusion injury.

The initial phase of neutrophil (PMN) adherence in the pathophysiology of myocardial ischemia-reperfusion (MI/R) injury depends on the selectins, particularly P- and L-selectin. Several ligands for these selectins have been identified, one of which may be a heparan sulfate proteoglycan (HSPG). Cats subjected to 90 min of MI and 270 min of R were given either heparinase III (0.033, 0.33 or 3.33 IU/kg/min) or its vehicle beginning 10 min before R and continuing throughout the 270-min R period. Heparinase III at 3.33 IU/kg/min provided a marked cardioprotective effect compared with cats receiving only vehicle as evidenced by a significant attenuation in myocardial necrosis (P < .01). In addition, endothelium-dependent vasorelaxation to acetylcholine in coronary artery rings isolated from MI/R cats treated with heparinase III was significantly preserved (P < .01). Adherence of PMNs to the coronary vascular endothelium after 270 min of R was also significantly attenuated in heparinase III-treated cats compared with vehicle (P < .01). At 0.33 IU/kg/min, heparinase III exerted modest, significant cardioprotective effects, whereas at 0.033 IU/kg/min, no significant beneficial effects were observed. Our results indicate that heparinase III is cardioprotective in a dose-dependent manner, preserves endothelial function and attenuates PMN adherence to the coronary vascular endothelium.

Animals↗
PubMed1996

Autocrine effects of endothelin-1 on leukocyte-endothelial interaction: stimulation of endothelin B receptor subtype reduces endothelial adhesiveness via a nitric oxide-dependent mechanism.

The effects of endothelin-1 (ET-1) on P-selectin-mediated leukocyte endothelial interaction were examined in vitro. Adherence of autologous polymorphonuclear leukocytes (PMNs) to the endothelium was markedly enhanced by endothelial stimulation with either (2 U/mL) thrombin, (1 mumol/L) histamine, or (100 nmol/L) phorbol myristate acetate (PMA). In contrast, ET-1 alone (10 and 100 nmol/L) only slightly increased the number of adhering PMNs. The increased PMN adherence to thrombin- or histamine-stimulated endothelium, which was blocked by an anti-P-selectin monoclonal antibody, was also significantly attenuated by preincubation of coronary segments with (100 nmol/L) ET-1. We further investigated the mechanism of this anti-adherence action of ET-1 on thrombin-stimulated endothelial adhesiveness. Preincubation of coronary segments with a selective ETA receptor antagonist, BQ485 (1 mumol/L), had no effect on ET-1 inhibition of thrombin-induced PMN adherence. In contrast, preincubation with a selective ETB receptor antagonist, BQ788 (1 mumol/L) significantly reversed ET-1 inhibition of thrombin-induced PMN adherence, whereas the selective ETB receptor agonist BQ-3020 mimicked the inhibitory action of ET-1 on thrombin-induced PMN adherence. Furthermore, (100 mumol/L) N omega-nitro-L-arginine methyl ester (L-NAME), a nitric oxide synthase (NOS) inhibitor, significantly attenuated ET-1 inhibition of thrombin-stimulated PMN adherence. These results suggest that ET-1 may inhibit P-selectin-mediated leukocyte-endothelial interaction via ETB receptor stimulation and subsequent endothelial NO formation. This autocrine effect of ET-1 may be involved in pathophysiologic states such as early atherogenesis by preventing leukocyte-endothelial interaction in constricted blood vessels.

Animals↗
PubMed1996

Blockade of platelet endothelial cell adhesion molecule-1 protects against myocardial ischemia and reperfusion injury in cats.

Polymorphonuclear leukocytes have been shown to play an important role in myocardial ischemia (MI) and reperfusion (R) injury. Since blockade of platelet-endothelial cell adhesion molecules (PECAM-1) inhibits neutrophil transmigration in vitro and in vivo, the effects of a polygonal Ab directed against PECAM-1 were examined in a feline model of Ml/R. We established cross-reactivity of our anti-human PECAM-1 Ab to cat coronary vasculature and neutrophils by immunohistochemistry and flow cytometry. The anti-PECAM-1 Ab markedly blocked leukocyte transmigration into the peritoneal cavity of cats after glycogen-induced peritonitis. Then, anti-PECAM-1 Ab (1 mg/kg) was tested to determine whether it attenuates MI/R injury in a well characterized feline model of Ml and R. Anti-PECAM-1 Ab administered 10 min before R significantly inhibited the myocardial necrosis seen 4.5 h post-R compared with that in MI/R cats treated with control isotype rabbit IgG (12 +/- 2 vs 29 +/- 4% of area at risk; p less than 0.01) and significantly attenuated the rise in plasma creatine kinase activity (p less than 0.05). The Ab did not prevent increases in cardiac myeloperoxidase activity within the affected regions and did not significantly inhibit autologous neutrophil adhesion to coronary endothelium after stimulation of either neutrophils (by leukotriene B4) or coronary endothelium (by thrombin) in vitro. These results indicate that in vivo blockade of PECAM-1 significantly attenuates MI/R injury, presumably by inhibiting transendothelial migration of neutrophils.

Animals↗
PubMed1996

Oligotide attenuates leukocyte-endothelial cell interaction via P-selectin in the rat mesenteric vascular bed.

A novel single stranded polydeoxyribonucleotide (oligotide) was studied for its ability to modulate leukocyte-endothelial cell interaction, by means of intravital microscopy in the rat mesenteric microvasculature. Superfusion of the rat mesentery with 50 microM NG-nitro-L-arginine methyl ester (L-NAME), caused a significant, time-dependent increase in leukocyte rolling and adherence compared to control rats superfused with Krebs-Henseleit solution. However, oligotide (15 mg/kg i.v.) consistently reduced the L-NAME-induced leukocyte rolling (62 +/- 14 vs. 23 +/- 3 cells/min; P < 0.02) and adherence (11 +/- 2 vs. 4 +/- 1 cells/100 microns length of venule P < 0.01), without altering systemic blood pressure or mesenteric venular shear rate. Moreover, immunohistochemical localization of P-selectin expression on mesenteric venules was significantly increased (P < 0.01) after exposure to L-NAME, which was significantly attenuated by oligotide (P < 0.05). Similar results were also obtained by flow cytometric analysis performed on rat platelets. Stimulation of rat platelets with L-NAME significantly (P < 0.05) increased the fluorescence intensity of P-selectin, while the concomitant treatment of isolated rat platelets with L-NAME plus oligotide significantly (P < 0.005) attenuated P-selectin fluorescence intensity. Our data demonstrate that in vivo administration of oligotide can reduce leukocyte rolling and adherence in the mesenteric rat microvasculature by attenuating P-selectin expression, and confirming the key role of nitric oxide as an important regulator of leukocyte-endothelial cell interaction.

Animals↗