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A M Lefer

Publications and source records attributed to A M Lefer.

At least 109 records · Page 6Linked to original sources
PubMed1994

Sialyl Lewisx-containing oligosaccharide exerts beneficial effects in murine traumatic shock.

We investigated the effects of a soluble sialyl Lewisx-containing oligosaccharide (SLex-OS) in a rat model of traumatic shock. Pentobarbital-anesthetized rats subjected to Noble-Collip drum trauma developed a shock state characterized by marked hypotension, a survival time of 85 +/- 15 min, significant increases in ileal myeloperoxidase (P < 0.01), and plasma free amino-nitrogen activities (P < 0.01). Treatment with SLex-OS (10 mg/kg) 10 min posttrauma prolonged survival time to 198 +/- 29 min (P < 0.01), significantly attenuated ileal myeloperoxidase activity (P < 0.01), and diminished the accumulation of plasma free amino-nitrogen (P < 0.01), drug vs. vehicle, respectively. Furthermore, endothelium-dependent relaxation to acetylcholine in superior mesenteric artery rings isolated from SLex-OS-treated shock rats was significantly preserved (70 +/- 6 vs. 40 +/- 5% relaxation). No beneficial effects were observed using a nonfucosylated control oligosaccharide. Moreover, addition of SLex-OS significantly inhibited unstimulated human polymorphonuclear neutrophil (PMN) adherence in vitro to trauma-activated superior mesenteric artery endothelium ex vivo (P < 0.001). Our results indicate that SLex-OS exerts beneficial effects in traumatic shock states by blocking selectin-mediated leukocyte-endothelium interaction, thus improving survival, attenuating intestinal PMN accumulation, and diminishing shock-induced tissue injury.

Animals↗
PubMed1994

PMN adherence to cat ischemic-reperfused mesenteric vascular endothelium under flow: role of P-selectin.

We studied polymorphonuclear leukocyte (PMN) adherence to cat ischemic-reperfused mesenteric artery and vein endothelia under conditions of flow in vitro. Under physiological shear rates, only a few PMNs adhered to non-ischemic-reperfused arterial and venous endothelia (11 +/- 2 and 20 +/- 3 PMN/mm2, respectively). However, after 60 min of ischemia and 20 or 120 min of reperfusion, a significant increase in PMN adherence to arterial endothelium was observed. At 20 min of reperfusion, 44 +/- 4 PMN/mm2 adhered, and at 120 min postreperfusion, 63 +/- 12 PMN/mm2 adhered (P < 0.01 from control). Moreover, a greater degree of PMN adherence occurred on the venous than on the arterial endothelium. Thus, 159 +/- 10 and 198 +/- 12 PMN/mm2 adhered to mesenteric venous endothelium isolated after 20 and 120 min reperfusion, respectively (P < 0.01 vs. arteries). Furthermore, addition of PB 1.3 (20 micrograms/ml), a monoclonal antibody against P-selectin, 5 min before perfusion with PMNs significantly attenuated the increase in PMN adherence to both arterial and venous endothelia (P < 0.01). These results indicate that PMN-endothelial interaction also occurs in conduit vessels after ischemia and reperfusion, although a more profound PMN adherence occurs in veins.

Animals↗
PubMed1994

Polymorphonuclear leukocyte-induced vasocontraction and endothelial dysfunction. Role of selectins.

The roles of selectin adhesion molecules (P- and L-selectin) and their counterreceptor sialyl Lewisx were investigated in polymorphonuclear leukocyte (PMN)-induced cat coronary vasocontraction and endothelial dysfunction. Unstimulated autologous PMNs (10(6) cells/mL) were added to organ chambers containing cat coronary artery rings stimulated with either thrombin (2 U/mL) or hydrogen peroxide (100 mumol/L). PMNs elicited a significant vasocontraction in thrombin- (119 +/- 14 mg) and hydrogen peroxide- (132 +/- 15 mg) stimulated coronary rings. This PMN-induced vasocontraction was significantly attenuated by pretreatment with either an anti-P-selectin, an anti-L-selectin monoclonal antibody (ie, MAb PB 1.3 and MAb DREG-200), or a sialyl Lewis(x)-containing oligosaccharide (SLe(x)-OS). Endothelial function as assessed by endothelium-dependent vasorelaxation to acetylcholine was also significantly attenuated after PMN-induced vasocontraction in stimulated coronary rings. This endothelial dysfunction was significantly prevented by either PB 1.3, DREG-200, or SLe(x)-OS. In contrast, endothelium-independent relaxation to acidified sodium nitrite was not altered by PMN incubation, indicating that vascular smooth muscle function was unaffected. Adherence of PMNs to coronary endothelium also significantly increased following stimulation of endothelium with either thrombin or hydrogen peroxide, but this was significantly attenuated by PB 1.3, DREG-200, or SLe(x)-OS. Thus, PMN-endothelial interaction mediated by either selectin adhesion molecules (ie, P-selectin and L-selectin) or sialyl Lewis(x) may play an important role in PMN-induced vasocontraction and endothelial dysfunction. This mechanism may be important in the early endothelial dysfunction observed following reperfusion of an ischemic coronary vasculature.

Animals↗
PubMed1994

Beneficial effect of SPM-5185, a cysteine-containing nitric oxide donor, in rat carotid artery intimal injury.

We studied the effects of an organic nitric oxide (NO) donor SPM-5185 in a rat carotid artery intimal injury model. Seven days after injury, the two end segments of the injured carotid arteries were studied for endothelial release of NO, and the middle segments were used for histological measurement of the intimal-to-medial (I/M) ratio and scanning electron microscopy of the luminal surface. The NO donor SPM-5185 or its non-NO-donating control compound SPM-5267 were infused intravenously at 30 micrograms/d. Full vasorelaxant responses of rat carotid arterial rings were obtained with the endothelium-dependent vasodilators acetylcholine (ACh), A23187, and the endothelium-independent vasodilator acidified NaNO2 in sham-operated control rings. Impaired relaxation occurred with 10 mumol/L ACh and 1 mumol/L A23187 in injured rings but not in rings infused with SPM-5185 for 7 days. Relaxation to 100 mumol/L acidified NaNO2 was not significantly different among any of the groups, indicating a normal vascular smooth muscle response after intimal injury. Morphometric analysis of injured carotid arteries given vehicle and SPM-5267 showed marked intimal thickening with an average I/M ratio of 0.78 +/- 0.03 and 0.74 +/- 0.05, respectively. SPM-5185 markedly attenuated intimal thickening, resulting in an I/M ratio of 0.13 +/- 0.03 (P < .01 from vehicle), representing an approximately 82% inhibition of intimal thickening. SPM-5185 infusion resulted in accelerated regeneration of endothelial cells on the intimal surface at 7 days.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Physiological concentrations of nitric oxide do not elicit an acute negative inotropic effect in unstimulated cardiac muscle.

We examined the effect of several nitric oxide (NO) donors, authentic NO gas, and L-arginine in isolated cat and rat papillary muscles. We did not observe significant inotropic effects in response to any NO donor (ie, SPM-5185, C87-3754, and S-nitroso-N-acetylpenicillamine [SNAP]) from 1 nmol/L to 100 mumol/L. Similarly, authentic NO, at concentrations far in excess of those that maximally dilate the coronary vasculature (ie, 500 nmol/L), also failed to exert a detectable inotropic effect in these preparations. However, in the presence of 5 mumol/L norepinephrine, 500 nmol/L NO exerted a 12 +/- 3% decrease in isolated rat papillary muscle contractility (P < .05). Addition of L-arginine up to 25 mmol/L exerted no inotropic effects in isolated rat papillary muscles. However, at 50 mmol/L, L-arginine decreased contractile force by 21 +/- 4% (P < .01). On further examination, the negative inotropic effect of 50 mmol/L L-arginine appeared to be nonspecific, since the inactive stereoisomer, D-arginine, at 50 mmol/L exerted the same effect. Further studies in isolated adult rat cardiac myocytes elicited similar results, in that 50 mmol/L of L- and D-arginine equally decreased contraction amplitude and the underlying cytosolic calcium transient. Moreover, 500 nmol/L of the NO donor SPM-5185 only modestly decreased contraction amplitude or intracellular calcium in isolated rat cardiac myocytes. These results indicate that administration of physiological concentrations of exogenous NO does not acutely depress the inotropic state of the rat or cat heart to a physiologically significant extent.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1994

Sialyl Lewisx-containing oligosaccharide attenuates myocardial reperfusion injury in cats.

Neutrophil (PMN) adhesion to the vascular endothelium is an important mechanism of myocardial reperfusion injury. The adhesion process is initially mediated by selectins (e.g., P- and L-selectin), and monoclonal antibodies directed against these adhesion molecules exert cardioprotective activity in ischemia/reperfusion models. The counterreceptors for these selectins are thought to be carbohydrate-containing moieties. In this connection, we studied the effect of a soluble sialyl Lewisx-containing oligosaccharide (SLex-OS) on PMN-endothelial interactions in a feline model of myocardial ischemia/reperfusion (MI/R). SLex-OS (10 mg/kg), administered 10 min before R, significantly reduced myocardial necrosis compared with its vehicle 270 min after reperfusion (6 +/- 1% vs. 35 +/- 4% of area at risk, P < 0.01). The cardioprotection was confirmed by significantly lower plasma creatine kinase activities in SLex-OS vs. vehicle-treated cats (P < 0.01). Cardiac contractility (dP/dt max) of cats receiving SLex-OS was significantly preserved after 270 min of R (97 +/- 2% vs. 78 +/- 5% of initial, P < 0.01). Furthermore, endothelium-dependent relaxation to acetylcholine in coronary artery rings isolated from MI/R cats treated with SLex-OS was significantly preserved (73 +/- 7% vs. 22 +/- 6% vasorelaxation, P < 0.01). In vitro PMN adherence to coronary vascular endothelium after 270 min of R was significantly attenuated in the SLex-OS-treated group compared with the vehicle group (14 +/- 5 vs. 91 +/- 12 PMN/mm2, P < 0.01). Our results indicate that a SLex-OS is cardioprotective and preserves coronary endothelial function after MI/R, indicating an important role of sialyl Lewisx in PMN accumulation, endothelial dysfunction, and myocardial injury in myocardial ischemia/reperfusion.

Animals↗
PubMed1994

Humanized monoclonal antibody DREG-200 directed against I-selectin protects in feline myocardial reperfusion injury.

Polymorphonuclear leukocytes (i.e. neutrophils) significantly mediate damage in myocardial ischemia followed by reperfusion. In the present study, the cardioprotective effects of a humanized form of a monoclonal antibody directed against L-selectin designated monoclonal antibody (mAb) HuDREG-200 were examined in a feline model of 90-min myocardial ischemia followed by 270 min of reperfusion. In preliminary studies, flow cytometric analysis indicated that HuDREG-200 binds to feline neutrophils. In vitro administration of mAb HuDREG-200 significantly inhibited (P < .01) adherence of unstimulated neutrophils to ischemic-reperfused coronary endothelium in a concentration-dependent manner. Humanized DREG-200 (2 mg/kg) administered 10 min before reperfusion significantly attenuated myocardial necrosis compared to an isotype-matched humanized control mAb (HuABL364) which does not bind to L-selectin (14 +/- 3 vs. 29 +/- 3% necrosis/area-at-risk, P < .01), representing a 52% reduction in myocardial necrosis. This myocardial preservation also was related to reduced creatine kinase release and improved recovery of cardiac contractility (i.e. left ventricular dP/dtmax). Moreover, endothelial function, as assessed by relaxation to acetylcholine, also was significantly preserved in ischemic-reperfused coronary arteries isolated from cats treated with mAb HuDREG-200 compared to mAb HuABL364 (68 +/- 6 vs. 18 +/- 5, P < .01). Thus, a humanized anti-L-selectin mAb appears to be an effective means of preserving the ischemic myocardium from reperfusion injury and of preserving myocardial contractile function, at least during the early reperfusion period.

Animals↗
PubMed1994

Effects of taprostene on neutrophil-endothelial interactions in isolated coronary arteries.

We examined the effects of taprostene (2.5 x 10(-8) M to 1 x 10(-7) M), a stable prostacyclin analog, on PMN-endothelial interaction (i.e., adherence) and subsequent vasocontraction and endothelial dysfunction. Taprostene effectively inhibited the adherence of leukotriene B4-stimulated autologous cat polymorphonuclear (PMN) leukocytes to isolated cat coronary artery endothelium. Taprostene also inhibited coronary artery vasocontraction to leukotriene B4-stimulated PMNs (p < 0.01). In isolated coronary artery rings stimulated with either 2 U/ml of thrombin or 100 microM hydrogen peroxide (H2O2), adherence of unstimulated PMNs to coronary endothelium was significantly increased, resulting in vasocontraction and subsequent endothelial dysfunction. However, taprostene (1 x 10(-7) M) significantly attenuated unstimulated PMN adherence to stimulated coronary endothelium. This antiadherence action effectively attenuated PMN-induced coronary artery vasocontraction (p < 0.01) and significantly blunted the subsequent PMN-induced endothelial dysfunction (p < 0.01) characterized by a loss of endothelium-derived nitric oxide (NO). Thus, taprostene exerts a profound inhibitory effect on PMN-endothelium interaction and subsequent PMN-mediated coronary endothelial dysfunction, which may be beneficial in ischemia-reperfusion and other inflammatory states.

Analysis of Variance↗
PubMed1994

Endothelial preserving actions of a nitric oxide donor in carotid arterial intimal injury.

We examined the actions of a nitric oxide donor, CAS754, in a rat model of carotid artery intimal injury. Seven days following injury, the injured carotid arteries were studied for endothelial release of nitric oxide (NO) and for histological measurement of the intimal/medial (I/M) ratio. Basal release of NO was assessed by NG-nitro-L-arginine methyl ester (L-NAME)-induced vasocontraction. L-NAME contracted injured rat carotid artery rings about 27% of that obtained in control rats (p < 0.01). However, CAS754 given at 30 mcg/day i.v. resulted in a L-NAME contraction of twice that of vehicle-treated rats (p < 0.01). A control compound lacking the NO moiety (C-3934) yielded a contraction to L-NAME comparable to untreated injured rats. We also tested the ability of rat carotid artery rings to relax to the endothelium-dependent vasodilators, acetylcholine and A23187. ACh (10 mcM) relaxed carotid artery rings only about 20% of control values in vehicle-treated and in C-3934-treated rats, compared with a vasorelaxation of over 80% of control in CAS754-treated rats (p < 0.01). Relaxation to acidified NaNO2 (100 mcM) was not significantly different among any of the groups of carotid arteries, indicating normal vascular smooth muscle responses following intimal injury. Morphometric assessment of carotid arteries isolated from injured rats given either vehicle or C-3934 showed marked intimal thickening with an average intimal/medial (I/M) ratio of 0.79 +/- 0.05 and 0.73 +/- 0.06, respectively, compared with 0.10 +/- 0.02 in non-injured arteries.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Mechanism of the cardioprotective effect of transforming growth factor beta 1 in feline myocardial ischemia and reperfusion.

We studied the effects of transforming growth factor beta 1 (TGF-beta 1) in a feline model of myocardial ischemia (1.5 hr) and reperfusion (4.5 hr). Myocardial ischemia followed by reperfusion resulted in severe myocardial injury, endothelial dysfunction, high cardiac myeloperoxidase activity indicative of neutrophil accumulation in the ischemic myocardium, and significant neutrophil adherence to the ischemic coronary endothelium. In contrast, intravenous administration of TGF-beta 1 (20 micrograms/kg) 30 min prior to reperfusion significantly attenuated myocardial necrosis (13.8% +/- 3.5% vs. 32.2% +/- 2.9% of area-at-risk, P < 0.01) and attenuated endothelial dysfunction (P < 0.01) associated with ischemia-reperfusion. Moreover, myeloperoxidase activity in the ischemic myocardium was significantly lower than vehicle controls (0.2 +/- 0.1 vs. 1.7 +/- 0.3 units/100 mg of tissue, P < 0.01) and neutrophil adherence to ischemic coronary endothelium was significantly (P < 0.01) attenuated in TGF-beta 1-treated cats. These results demonstrate that TGF-beta 1 exerts a significant cardioprotective effect in a feline model of myocardial ischemia and reperfusion. The mechanism of this protective effect appears to relate to endothelial preservation by TGF-beta 1 inhibiting circulating neutrophils from adhering to the endothelium, a critical step in neutrophil-induced reperfusion injury.

Animals↗
PubMed1993

Cytokines and growth factors in endothelial dysfunction.

OBJECTIVE: The purpose of this focused review is to call attention to the important interrelationships between growth factors (e.g., transforming growth factor-beta) and cytokines (e.g., tumor necrosis factor [TNF]) on endothelial function as characterized by the ability of the endothelium to release endothelium-derived relaxing factor. BACKGROUND AND METHODS: Myocardial ischemia followed by reperfusion leads to a severe degree of endothelial dysfunction characterized by an impaired vasodilator response to endothelial-dependent vasodilators. The reduction in endothelial-dependent responses occurs rapidly after the onset of reperfusion. Endothelial dysfunction was studied in coronary artery as well as superior mesenteric artery rings, and the effects of cytokines, transforming growth factor-beta, and free radicals were assessed. RESULTS: Oxygen-derived free radicals (i.e., superoxide anion) and cytokines (i.e., TNF) contribute to this endothelial dysfunction, which is characterized by a loss of endothelium-derived relaxing factor, now known to be identical to nitric oxide. Agents such as superoxide dismutase or transforming growth factor-beta can significantly preserve endothelial integrity during ischemia-reperfusion states. CONCLUSIONS: Endothelial dysfunction is an early and critical phenomenon occurring in ischemia-reperfusion injury both in the coronary and the mesenteric circulations.

Animals↗
PubMed1993

Pharmacology of the endothelium in ischemia-reperfusion and circulatory shock.

Endothelial dysfunction is an important early-recurring phenomenon in virtually all forms of ischemia-reperfusion, including a variety of circulatory shock states. The dysfunction appears to be triggered within 2.5 min of the endothelial generation of a large burst of superoxide radicals. However, the initial dysfunction may be amplified by neutrophil-generated factors including oxygen-derived free radicals, cytokines, proteases, and lipid mediators. Moreover, adhesive molecules on the surface of the PMN, along with their ligands on the endothelial cell membrane, appear to promote endothelial dysfunction in ways that may go beyond the adherence of neutrophils on the endothelial surface. These interactions remain to be elucidated but may involve intricate cell signaling pathways. A variety of pharmacologic agents exert endothelial protective effects in ischemia-reperfusion and circulatory shock states. Table 1 summarizes these agents and indicates the major mechanism of preservation of the endothelium. These substances can be classified into three broad categories: (a) substances replacing endogenous cytoprotective agents of endothelial origin including prostacyclin (PGI2), endothelium-derived relaxing factor (EDRF), and adenosine: the endothelium protecting agents include these substances as well as stable analogs of PGI2, and nitric oxide donors; (b) substances that inhibit pro-inflammatory mediators of endothelial origin: the pro-inflammatory agents are primarily platelet activating factor (PAF) and oxygen-derived free radicals (e.g. superoxide radicals) although other mediators may be involved. The therapeutic agents useful in this area are PAF receptor antagonists and free radical scavengers (e.g. superoxide dismutase); (c) substances that inhibit neutrophils or neutrophil-derived mediators: the major neutrophil-derived mediators are oxygen-derived free radicals, cytokines (e.g. TNF alpha and IL-1 beta), proteases (e.g. elastase), and lipid mediators (e.g. LTB4). In addition, adhesive molecules on the neutrophil surface and their endothelial ligands promote endothelial dysfunction and the action of adherent neutrophils. Agents that inhibit some of these mediators are transforming growth factor-beta (TGF-beta), elastase inhibitors, leukotriene B4 (LTB4) receptor antagonists and monoclonal antibodies to adhesive proteins (e.g. anti-CD18, anti-ICAM-1). Further work is needed to clarify these findings and to determine the physiologic and pathophysiologic interactions among these diverse agents. This topic of endothelial dysfunction represents a fertile area for further investigation to elucidate the complex mechanisms of neutrophil-endothelial interactions. These interactions lead to neutrophil adherence to the endothelium, neutrophil migration into the underlying tissues, and subsequent tissue injury (e.g. myocardial reperfusion injury).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1993

Decreased basal nitric oxide release in hypercholesterolemia increases neutrophil adherence to rabbit coronary artery endothelium.

Hypercholesterolemia, before atherosclerosis, is known to reduce agonist- (e.g., acetylcholine) mediated nitric oxide (NO) production within 2 weeks of a cholesterol-enriched diet. However, no data exist on the effect of hypercholesterolemia on the basal release of NO from blood vessels. We studied the basal release of NO in rabbit coronary arteries by addition of the NO synthase blocker NG-nitro-L-arginine-methyl ester (L-NAME). Basal release of NO was markedly attenuated 2 weeks after introduction of a 0.5% cholesterol addition to the diet. One week later, the adherence of neutrophils to the coronary endothelium was significantly enhanced (i.e., threefold; p < 0.01 different from control). The increased adhesiveness could be attributed to enhanced endothelial adhesion rather than to changes in the properties of the leukocytes. Both phenomena could be reversed by addition of L-arginine to isolated coronary arteries. Administration of 10 mg/day lovastatin, a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, markedly attenuated both the reduced basal NO production and the increased adhesiveness of the endothelium. These results support the concept that NO is an important protective agent produced by the endothelium to preserve the integrity of the endothelium and may protect it against atherogenesis.

Amino Acid Oxidoreductases↗
PubMed1993

Monoclonal antibody to L-selectin attenuates neutrophil accumulation and protects ischemic reperfused cat myocardium.

BACKGROUND: Interaction of CD11/CD18 located on neutrophil membranes with its endothelial counter-receptor, intercellular adhesion molecule-1, plays a major role in polymorphonuclear leukocyte (PMN)-mediated endothelial dysfunction and myocardial injury associated with ischemia and reperfusion. However, PMN-derived L-selectin, which is thought to play an early role in PMN rolling along the vascular endothelium, has not been studied in a setting of myocardial ischemia and reperfusion. METHODS AND RESULTS: In this study, we evaluated the effects of a monoclonal antibody against L-selectin, DREG-200, in a feline model of myocardial ischemia (1.5 hours) and reperfusion (4.5 hours). DREG-200 (1 mg/kg) or an isotype-matched IgG1 antibody, MAb R3.1, which does not cross-react in cats, was administered as a bolus 10 minutes before reperfusion. In MAb R3.1-treated cats, myocardial ischemia followed by reperfusion resulted in significant coronary vascular endothelial dysfunction, elevated cardiac myeloperoxidase activity indicative of neutrophil accumulation in the ischemic myocardium, and severe myocardial injury. In contrast, administration of DREG-200 at 1 mg/kg significantly attenuated myocardial necrosis (14 +/- 4 versus 32 +/- 3 expressed as percentage of area at risk, P < .001) and attenuated coronary endothelial dysfunction (P < .01) associated with ischemia/reperfusion. Moreover, myeloperoxidase activity in the ischemic myocardium was significantly lower than MAb R3.1-treated cats (0.4 +/- 0.1 versus 0.9 +/- 0.2 U/100 mg tissue, P < .05). CONCLUSIONS: These results demonstrate that blocking L-selectin with DREG-200 exerts a significant cardioprotective effect in a feline model of myocardial ischemia and reperfusion, indicating that L-selectin plays a significant role in mediating PMN accumulation and PMN-induced endothelial and myocardial injury after ischemia and reperfusion.

Animals↗
PubMed1993

Diminished basal nitric oxide release after myocardial ischemia and reperfusion promotes neutrophil adherence to coronary endothelium.

We measured changes in basal release of nitric oxide and its effect on polymorphonuclear leukocyte (PMN) adherence to endothelial cells (ECs) in a feline model of myocardial ischemia (90 minutes) and reperfusion. Basal release of nitric oxide from the left anterior descending coronary artery (LAD) after myocardial ischemia/reperfusion and from the control left circumflex coronary artery (LCX) was assessed by NG-nitro L-arginine methyl ester (L-NAME)-induced vasocontraction. L-NAME induced a significant EC-dependent vasocontraction in control LCX rings (0.28 +/- 0.04 g), which was fully reversed by L-arginine but not D-arginine. L-NAME-induced vasocontraction of LAD rings was not significantly changed after 90 minutes of myocardial ischemia without reperfusion. However, 10 minutes of reperfusion reduced the L-NAME-induced vasocontraction to 0.13 +/- 0.04 g (p < 0.05), and this was restored by addition of 3 mM L-arginine but not D-arginine. Longer periods of reperfusion progressively decreased L-NAME-induced vasocontraction. After 270 minutes of reperfusion, L-NAME-induced vasocontraction was virtually abolished. Myocardial ischemia without reperfusion did not increase PMN adherence to ECs. However, PMN adherence to LAD ECs was significantly increased after 20 minutes of reperfusion (39 +/- 6 to 105 +/- 9 PMNs/mm2, p < 0.01), and incubation of LAD segments with L-arginine significantly attenuated this increase in PMN adherence. After 270 minutes of reperfusion, PMN adherence to LAD ECs was further increased to 224 +/- 10 PMNs/mm2 (p < 0.001). This increase in PMN adherence was almost completely blocked by MAb R15.7, a monoclonal antibody against CD18 of PMNs, and was significantly attenuated by MAb RR1/1, a monoclonal antibody against intercellular adhesion molecule-1 of ECs (p < 0.01). These results indicate that decreased basal release of endothelium-derived relaxing factor after myocardial ischemia/reperfusion precedes enhanced PMN adherence to the coronary endothelium, which may lead to PMN-induced myocardial injury.

Animals↗
PubMed1993

In vivo neutralization of P-selectin protects feline heart and endothelium in myocardial ischemia and reperfusion injury.

The cardioprotective effects of an mAb to P-selectin designated mAb PB1.3 was examined in a feline model of myocardial ischemia (MI) and reperfusion. PB1.3 (1 mg/kg), administered after 80 min of ischemia (i.e., 10 min before reperfusion), significantly attenuated myocardial necrosis compared to a non-blocking mAb (NBP1.6) for P-selectin (15 +/- 3 vs 35 +/- 3% of area at risk, P < 0.01). Moreover, endothelial release of endothelium derived relaxing factor, as assessed by relaxation to acetylcholine, was also significantly preserved in ischemic-reperfused coronary arteries isolated from cats treated with mAb PB1.3 compared to mAb NBP1.6 (67 +/- 6 vs 11 +/- 3, P < 0.01). This endothelial preservation was directly related to reduced endothelial adherence of PMNs in ischemic-reperfused coronary arteries. Immunohistochemical localization of P-selectin was significantly upregulated in the cytoplasm of endothelial cells that lined coronary arteries and veins after 90 min of ischemia and 20 min of reperfusion. The principal site of intracytoplasmic expression was in venous vessels. mAb PB1.3 significantly decreased (P < 0.01) adherence of unstimulated PMNs to thrombin and histamine stimulated endothelial cells in a concentration-dependent manner in vitro. These results demonstrate that PMN adherence to endothelium by P-selectin is an important early consequence of reperfusion injury, and a specific monoclonal antibody to P-selectin exerts significant endothelial preservation and cardioprotection in myocardial ischemia and reperfusion.

Animals↗