Bone marrow stem cell imaging after intracoronary administration.

Although feasibility and safety of autologous stem cells administration to the post-infarction heart has been proven it is not known what proportion of cells effectively do home at the damaged site. Therefore, we have labeled autologous bone marrow cells (ABMC's) by radioactive Indium and single photon emission computed tomography (SPECT) tissue distribution has been analyzed. It was detected that up to 10% of the cells were retained within the myocardium while their majority migrated or has been anchored at the spleen and liver. Comparing the number of homed cells to the total number of cells delivered one may postulate the indirect role for few hundred thousands ABMC's at heart regeneration.

Stimulation of neutrophil activation during coronary artery bypass grafting: comparison of crystalloid and blood cardioplegia.

BACKGROUND: During myocardial ischemia, activation of polymorphonuclear neutrophils (PMNs) results in the production of free oxygen radicals, which increase myocardial injury. It has been shown that PMNs also produce nitric oxide. It is not clear whether PMNs become activated as a result of their direct contact with ischemic/reperfused myocardium or if PMN activation and free oxygen radical production are effects of specific stimuli released during coronary artery bypass grafting (CABG). The aim of the current study was to evaluate plasma-mediated neutrophil stimulation and production of superoxide anion (O2) and nitric oxide in patients undergoing CABG, and to verify whether crystalloid and blood cardioplegia can modify such stimulation. METHODS: Coronary sinus, peripheral arterial, and venous plasma samples were collected from 50 patients who underwent CABG and were divided into 2 equal groups which received either crystalloid or blood cardioplegia: directly before myocardial ischemia and aortic cross-clamping; at the beginning of reperfusion after aortic clamp release; and 30 minutes after reperfusion. O2 and nitric oxide production by PMN was evaluated by standard methods. RESULTS: There was a significant (p < 0.05) increase in O2 production by PMN incubated with plasma obtained from the coronary sinus immediately after reperfusion in patients receiving crystalloid cardioplegia compared to blood cardioplegia. No difference was observed in plasma stimulation of nitric oxide production by PMN in the 2 groups of patients at different times during the procedure. CONCLUSIONS: Cardioplegia may affect release of neutrophil-oriented stimuli from ischemic myocardium and modify neutrophil activation during coronary artery bypass grafting.

Stimulation of neutrophil integrin expression during coronary artery bypass grafting: comparison of crystalloid and blood cardioplegic solutions.

OBJECTIVES: This study was designed (1) to evaluate the influence of plasma obtained from patients undergoing coronary artery bypass grafting on L-selectin, CD11b, and CD18 expression on human neutrophils and (2) to determine the influence of the use of crystalloid or blood cardioplegia during bypass grafting on plasma-mediated expression of adhesion molecules on polymorphonuclear neutrophils. PATIENTS AND METHODS: Patients undergoing coronary artery bypass grafting were divided into 2 groups to receive crystalloid or blood cardioplegic solutions. Peripheral vein, radial artery, and coronary sinus blood samples were drawn at aortic crossclamping, aortic crossclamp release, and 30 minutes after reperfusion. Human neutrophils were incubated with patients' plasma, and the expression of CD11b, CD18, and L-selectin was determined with flow cytometry. RESULTS: In patients receiving crystalloid cardioplegic solutions, plasma samples collected from the coronary sinus at aortic clamp release and 30 minutes thereafter induced significantly higher expression of neutrophil CD11b and CD18 than plasma samples obtained from a peripheral vein or artery at the same time points. The expression of L-selectin on polymorphonuclear neutrophils was significantly reduced with plasma obtained 30 minutes after reperfusion as compared with samples collected at aortic crossclamp release. In the group receiving blood cardioplegia, no significant differences in CD11b, CD18, or L-selectin expression were found. CONCLUSIONS: (1) Ischemia/reperfusion after coronary artery bypass grafting is associated with the release of factors capable of neutrophil activation from myocardium into the circulating blood. (2) The release of soluble stimuli for neutrophils during bypass grafting may be modified by the cardioplegic solution.

Plasma-mediated stimulation of neutrophil superoxide anion production during coronary artery bypass grafting: role of endothelin-1.

BACKGROUND: Activation of polymorphonuclear neutrophils (PMN) and subsequent release of free oxygen radicals, including the superoxide anion (O2-) has been shown to result in postischaemic myocardial dysfunction during coronary artery bypass grafting (CABG). Several neutrophil-oriented stimuli are known to be released from myocardium during ischaemia and reperfusion. Release of endothelin-1 has been documented during CABG. The aim of the current study was to evaluate plasma-mediated neutrophil stimulation and to verify whether endothelin-1, known to be a stimulus for PMN, is involved in plasma-mediated stimulation of PMN during coronary artery bypass grafting. METHODS: Plasma samples from peripheral artery, peripheral vein, and coronary sinus were obtained from 21 patients undergoing CABG before aortic clamping (global ischaemia), immediately after beginning reperfusion, and 30 min after reperfusion as well as from healthy controls. Plasma was incubated with PMN isolated from healthy donors preincubated in the presence of saline or specific endothelin-1 receptor antagonist (ET-A). PMN O2- production was measured spectrophotometrically. RESULTS: Plasma samples taken from the coronary sinus at the beginning of reperfusion were capable of higher stimulation of neutrophil superoxide anion production (24.2 +/- 2.0 nmol/5 x 10(6)PMN/30 min) than plasma obtained before reperfusion (15.6 +/- 1.5; p < 0.05) or plasma taken from peripheral artery (17.1 +/- 1.7; p < 0.05). Preincubation of PMN with endothelin-1 receptor antagonist decreased superoxide anion production by cells exposed to plasma taken from coronary sinus at the beginning of reperfusion (17.6 +/- 2.0, p < 0.05). CONCLUSIONS: Transcardiac release of soluble stimuli for PMN occurs as a result of myocardial ischaemia during CABG. Endothelin-1 may be involved in the plasma-mediated stimulation of neutrophil superoxide anion production.

The effects of dipyridamole stress test on plasma levels of soluble adhesion molecules intracellular adhesion molecule-1, vascular cell adhesion molecule-1, E-selectin and L-selectin in patients with ischemic heart disease and patients with syndrome X.

BACKGROUND: Adhesion of activated leukocytes to the endothelium as a result of myocardial ischemia/reperfusion has been shown to be involved in the development of tissue injury. Leukocyte adhesion to the endothelium occurs via adhesion molecules expressed on the surface of both cell types. Upon cell activation these proteins may be released into the circulation and measured in a soluble form. AIM: To verify whether the dipyridamole stress test, performed in patients with ischemic heart disease (IHD) and in patients with syndrome X, modifies plasma levels of the soluble adhesion molecules vascular cell adhesion molecule-1 (VCAM-1), intracellular adhesion molecule-1 (ICAM-1), E-selectin and L-selectin. METHODS: Plasma levels of the soluble endothelial adhesion molecules ICAM-1, VCAM-1 and E-selectin, as well as of the soluble leukocyte adhesion molecule L-selectin, were measured in venous blood samples taken before and 7 min after administration of dipyridamole in patients with IHD, patients with syndrome X and healthy individuals. Myocardial perfusion was evaluated using single photon emission tomography. The plasma levels of soluble VCAM-1, ICAM-1, E-selectin and L-selectin were all measured using enzyme-linked immunosorbent assays. RESULTS: After infusion of dipyridamole, plasma levels of ICAM-1 increased significantly in patients with IHD, whereas they remained unchanged in patients with syndrome X and in the control group. In patients with IHD, the initial plasma levels of VCAM-1, E-selectin and L-selectin, before administration of dipyridamole, were higher than those observed in patients with syndrome X and than those in the control group. Plasma levels of soluble VCAM-1, E-selectin and L-selectin decreased significantly in patients with IHD following the dipyridamole stress test, whereas they remained unchanged in patients with syndrome X, and in the control group. CONCLUSION: In patients with IHD, administration of dipyridamole induces myocardial ischemia resulting in modification of plasma levels of the soluble adhesion molecules.

Endothelin-1 is involved in plasma mediated stimulation of neutrophil adherence during coronary artery bypass grafting.

OBJECTIVE: Myocardial ischaemia followed by reperfusion during coronary artery bypass grafting (CABG) is known to result in the activation of polymorphonuclear neutrophils (PMN). The activation of PMN during ischaemia/reperfusion may be a result of their direct contact with activated endothelial cells and/or an effect of stimuli released from ischaemic myocardium. Increased expression of adhesion molecules on the PMN surface, after activation, leads to coronary capillary plugging with a subsequent decrease in blood flow. The purpose of the study was to evaluate plasma-mediated stimulation of PMN adhesion during CABG and to verify if endothelin-1 (ET-1), known to be a potent stimulus for PMN, is involved in stimulation of neutrophils adhesion mediated by integrins. METHODS: Coronary sinus, peripheral artery and peripheral venous plasma samples were taken from 11 patients undergoing coronary surgery before aortal cross-clamping, at the beginning of reperfusion and 30 min thereafter. PMN isolated from five healthy volunteers were incubated with the plasma (20 samples per patient) in the presence of saline or a specific ET-1 receptor blocker, and PMN adherence to a microtiter plate covered with a monoclonal antibody against CD 18 antigen (beta-subunit of the integrin family of adhesion molecules) was evaluated. RESULTS: We have observed a significant increase in adhesion of PMN incubated in the presence of saline with the plasma taken from coronary sinus at the beginning of reperfusion (7.79+/-1.64% of adhering cells) as compared with plasma obtained before aortal cross-clamping from the same place (6.78+/-1.3%, P = 0.04) and from peripheral artery at the beginning of reperfusion (6.64+/-1.1%, P = 0.04, means +/- SEM). ET-1 receptor blocker, significantly decreased stimulation of PMN adhesion by coronary sinus plasma obtained at the beginning of reperfusion (6.7+/-1.51%, P = 0.02). Plasma levels of ET-1 (ELISA) in the samples taken from coronary sinus at the beginning of reperfusion, were higher than in samples obtained before myocardial ischaemia or 30 min after reperfusion. CONCLUSIONS: We conclude, that soluble stimuli capable of stimulation of PMN adhesion are released following myocardial ischaemia during CABG and ET-1 may be involved in PMN stimulation.

Soluble adhesion molecules in reperfusion during coronary bypass grafting.

OBJECTIVE: Adhesion of activated leukocytes to the endothelial cells as a result of myocardial ischaemia/reperfusion during open chest coronary artery surgery has been shown to be involved in the development of tissue damage. Activated leukocytes adhere to endothelium via adhesion molecules expressed by both cell types, resulting in the impairment of coronary capillary flow. Upon cell activation, adhesion proteins may be released in the soluble form to circulating blood. The purpose of our study was to verify whether myocardial ischaemia/reperfusion occurring during coronary artery bypass grafting results in release of the soluble adhesion molecules VCAM-1, ICAM-1, E-selectin and L-selectin into the circulation. METHODS: Plasma levels of the soluble adhesion molecules were measured in vein, arterial and coronary sinus blood samples taken from 15 patients undergoing coronary artery bypass grafting (CABG). Blood samples for estimations were collected during the procedure: before aorta cross-clamping, at the beginning of reperfusion and 30 min after reperfusion. Soluble adhesion molecules levels were measured by standard ELISA assays. RESULTS: Mean plasma levels of soluble VCAM-1 in arterial samples increased significantly at the beginning of reperfusion and 30 min after reperfusion. In contrast, soluble L-selectin plasma levels in arterial samples remained unchanged. In coronary sinus samples, levels of soluble ICAM-1 significantly increased 30 min after reperfusion. Moreover, in coronary sinus samples collected 30 min after reperfusion, soluble ICAM-1 levels were significantly higher than in arterial samples obtained at the same time. The mean concentration of soluble E-selectin in samples obtained from coronary sinus decreased significantly 30 min after reperfusion. Moreover, plasma levels of soluble E-selectin in coronary sinus samples obtained 30 min after reperfusion were significantly decreased compared with these observed in arterial samples collected at the same time. CONCLUSIONS: The reperfusion of ischaemic myocardium during CABG results in a significant increase in plasma levels of the soluble endothelial adhesion molecules VCAM-1 and ICAM-1 and significant decrease in soluble E-selectin plasma levels. L-selectin plasma levels during CABG procedure remain unchanged. We propose that the increased plasma concentrations of soluble VCAM-1 and ICAM-1 are a result of endothelial cell activation during ischaemia/reperfusion following bypass surgery.

Increased release of the soluble form of the adhesion molecules L-selectin and ICAM-1 but not E-selectin during attacks of angina pectoris.

Myocardial ischemia leads to the activation of neutrophils as well as endothelial cells. The interaction between these cells is dependent on certain adhesion glycoproteins which are expressed on their surface. Adhesion of neutrophils to endothelium, mediated by adhesion molecules, has been shown to result in coronary capillary plugging and impairment of coronary blood flow. In certain conditions, upon cell activation, adhesion proteins may be released in soluble form into the circulating blood. The purpose of our study was to verify whether myocardial ischemia occurring during angina episodes results in the release of the soluble adhesion molecules, L-selectin, E-selectin, and intracellular adhesion molecule-1 (ICAM-1), into the circulation. Plasma samples were collected by venepuncture from 15 patients admitted to the emergency room with chest pain caused by attacks of angina pectoris and 15 patients with noncardiac chest pain. To confirm the diagnosis, all patients underwent an exercise stress test and, if not conclusive, 99mTc MIBI SPECT or coronary arteriography. Another set of plasma samples were taken from each patient in the absence of chest pain. In addition, blood for analysis was obtained from 15 sex-and age-matched healthy subjects. Soluble adhesion molecules plasma levels were measured by standard enzyme-linked immunosorbent assay. In patients with angina pectoris, plasma levels of soluble L-selectin estimated during chest pain were significantly higher than in the control group and decreased in the absence of chest pain. Similarly, the mean concentration of soluble ICAM-1 at the time of angina onset was significantly elevated in the patients in comparison with the control group and remained higher, although not significantly, in the absence of chest pain. In patients with noncardiac chest pain, plasma levels of soluble L-selectin did not differ significantly from those observed in control subjects. In this group of patients, the plasma levels of soluble ICAM-1 estimated during pain onset and in the absence of this symptom were not significantly elevated. On the contrary, the mean values of soluble E-selectin in the patients with ischemic cardiac pain during chest pain and in the absence of this symptom, as well as those in the patients with noncardiac chest pain during or without symptoms, remained unchanged in comparison with the control group. During attacks of angina pectoris an increase in the plasma levels of the soluble adhesion molecules, ICAM-1 and L-selectin, was noted, possibly reflecting activation of neutrophils and endothelial cells during myocardial ischemia. However, E-selectin plasma levels remained unchanged in response to myocardial ischemia.

The release of soluble adhesion molecules ICAM-1 and E-selectin after acute myocardial infarction and following coronary angioplasty.

Endothelial cells express surface adhesion molecules for leukocytes in response to myocardial ischaemia. These molecules may be released into plasma by activated cells and be detectable in soluble form. Samples were collected from the peripheral vein of 14 consecutive patients with acute myocardial infarction (AMI) at the time of admission, 6 h, and 1 and 5 days post-admission. Additionally, samples were drawn from the coronary sinus ostium and peripheral artery of seven patients undergoing coronary angioplasty (PTCA) before and after the first balloon inflation. We measured the plasma levels of soluble intercellular adhesion molecule-1 (sICAM-1) and soluble E-selectin (sELAM-1). In patients with AMI plasma levels of sICAM-1 exceeded those observed in age and sex-matched healthy subjects, (mean+/-SEM; 220.6+/-18 ng/ml) at all the time intervals assessed (358.9+/-24.5; 330.9+/-24.4; 379.4+/-39.7 and 366.8+/-47.5 ng/ml, respectively, p<0.01). sELAM-1 levels, however, were normal on admission, increased at 6 h to 52.7+/-3.8 ng/ml, p<0.05, and at day 1 (56.0+/-4.6 ng/ml) before decreasing to normal levels on the fifth day. After brief myocardial ischaemia occurring during PTCA, an increased level of sICAM-1 was observed following balloon deflation in the coronary sinus (329.2+/-20 ng/ml; p<0.05) as compared to the subjects undergoing coronary angiography, but not in the peripheral artery. sELAM-1 levels remained unchanged during angioplasty. Thus, soluble adhesion molecules expressed by activated endothelial cells are released into peripheral blood during both AMI and brief myocardial ischaemia and measurement of such molecules may prove useful for monitoring vascular endothelium activation following myocardial ischaemia/necrosis.

Plasma mediated neutrophil stimulation during coronary angioplasty: autocrine effect of platelet activating factor.

BACKGROUND: Polymorphonuclear neutrophils are involved in the development of myocardial injury during ischaemia and reperfusion. Coronary angioplasty has been shown to result in neutrophil activation. This may be a result of contact with ligands expressed by endothelial cells or response to soluble stimuli released from ischaemic tissue into the plasma or both. OBJECTIVE: To investigate plasma mediated neutrophil activation during angioplasty. METHODS AND RESULTS: Plasma samples were collected from the coronary sinus, femoral artery, and femoral vein of 14 patients undergoing angioplasty, before and after the first balloon inflation and at the end of the procedure. Plasma samples were incubated with washed neutrophils isolated from healthy donors. Expression of the adhesion molecules CD18 integrin and L-selectin (Leu-8) was measured by flow cytometry, and superoxide anion production was measured by chemiluminescence. Plasma samples from the coronary sinus and femoral artery but not from the peripheral vein induced increased expression of neutrophil CD18 after balloon deflation. Modification of the expression of L-selectin was not noted. Production of superoxide anion by neutrophils was stimulated by plasma samples from the coronary sinus, but not by those from the femoral artery or vein. This plasma mediated neutrophil stimulation was prevented when the neutrophils were pretreated with platelet activating factor receptor antagonists BN52021 or BN50739. The platelet activating factor concentration detected in the coronary sinus was not higher than in control plasma. CONCLUSION: Brief ischaemia during coronary angioplasty leads to the release of soluble stimuli capable of inducing neutrophil integrin expression and free oxygen radical production. Platelet activating factor may act as an autocrine neutrophil stimulus under these conditions.

Plasma-mediated neutrophil activation during acute myocardial infarction: role of platelet-activating factor.

1. Polymorphonuclear neutrophils are involved in the development of myocardial injury during ischaemia through the release of free oxygen radicals and by adhesion of activated polymorphonuclear neutrophils to endothelium, resulting in plugging of coronary capillaries. Polymorphonuclear neutrophil activation may be a result of contact with ligands expressed by endothelial cells and/or a response to soluble stimuli released from ischaemic tissue to the plasma. 2. To investigate this we studied plasma-mediated polymorphonuclear neutrophil activation in vitro using plasma samples collected from 14 patients with acute myocardial infarction at time of admission and 6 h and 1, 2, 5 and 7 days later. Plasma samples were incubated with washed polymorphonuclear neutrophils isolated from healthy donors. Expression of adhesion molecules CD18/CD11b integrin and L-selectin (Leu-8) were measured by flow cytometry and superoxide anion production in polymorphonuclear neutrophils was measured by chemiluminescence. 3. Plasma samples obtained 6 h and 1 day after admission were capable of inducing CD18/CD11b antigen expression, superoxide anion production and L-selectin shedding in the washed polymorphonuclear neutrophils, and this effect was significant when compared with plasma taken at 5 and 7 days after admission. 4. The plasma-mediated polymorphonuclear neutrophil stimulation was prevented when the PMN were pretreated with platelet-activating factor receptor antagonists BN52021 or BN50739. The platelet-activating factor concentrations detected in the plasma samples were not higher than those detected in plasma from healthy subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Neutrophil interactions with endothelium and platelets: possible role in the development of cardiovascular injury.

Polymorphonuclear neutrophils (PMN) cause myocardial injury during ischaemia and reperfusion by their direct effects on the myocardium; PMN release highly cytotoxic free oxygen radicals and proteolytic enzymes and PMN aggregates are involved in capillary plugging and the no-reflow phenomenon. In addition, PMN-derived factors including free oxygen radicals, lipoxygenase products, cytokines and proteolytic enzymes have been shown to modify the function of endothelium and platelets. However, both endothelium and platelets are capable of modulating PMN activation. Endothelial cells modulate PMN function by the expression of adhesion molecules and by release of soluble factors including nitric oxide, prostacyclin, endothelins, platelet activating factor and interleukin-8. Platelets affect PMN activation by release of thromboxane A2, platelet derived growth factor, serotonin, lipoxygenase products, proteases and adenosine. Thus, in addition to their direct injurious effect on ischaemic myocardium, neutrophils are involved in the functional balance between endothelium and platelets and exert an indirect effect on the myocardium.

Evaluation of the effect of oral enalapril on neutrophil functions: comparison with the in vitro effect of enalapril and enalaprilat.

Polymorphonuclear neutrophils (PMN) participate in the development of myocardial injury by releasing free oxygen radicals and by involvement in the no-reflow phenomenon. Neutrophil-mediated myocardial injury, therefore contributes to the pathogenesis of heart failure. We investigated the effect of oral treatment with enalapril on neutrophil free oxygen radical production, aggregation and adherence in patients with moderate heart failure (New York Heart Association-NYHA II and III degrees). Samples were taken before and 48 h after a single 10 mg oral dose. Oral enalapril inhibited hydrogen peroxide released by unstimulated PMN, but did not affect stimulated H2O2 release, superoxide anion production, adhesion or aggregation of PMN. Enalaprilat in vitro stimulated PMN to release H2O2 and superoxide anions. Furthermore, in the in vitro conditions both enalaprilat and enalapril inhibited hydrogen peroxide release by stimulated cells. We conclude that, despite certain modifications of neutrophil function in vitro, oral administration of enalapril seems to exert a limited biological effect on circulating neutrophils.

Modulation of neutrophil activity by nitric oxide during acute myocardial ischaemia and reperfusion.

Nitric oxide (NO) exerts an inhibitory effect on polymorphonuclear neutrophil (PMN) function, via a cyclic GMP-mediated mechanism, while PMNs are known to play an important role in myocardial ischaemia-reperfusion injury (MI-R). Since the major source of NO, vascular endothelium, becomes functionally impaired during MI-R, it is attractive to hypothesize that it is this loss of endothelial nitric oxide production that allows PMN adherence and activation. The studies reviewed here add substance to this hypothesis. Authentic NO, administered during MI-R both reduces myocardial necrosis and PMN accumulation, while basal NO release, as estimated by coronary artery ring responses to L-NAME, an NO synthase inhibitor, declines during reperfusion with a time-course mirrored by PMN adherence in the same preparation. Reduction in infarct size and decreased PMN accumulation can also be demonstrated with L-arginine and NO donors. Since endothelial dysfunction leads to PMN adherence and PMNs have been shown to contribute to endothelial dysfunction, it seems probable that a positive feedback loop is generated during MI-R, leading to the amplification of PMN activity and subsequent myocardial damage.

Evidence for stimulation of neutrophil degranulation by selected angiotensin converting enzyme inhibitors in vitro.

Polymorphonuclear neutrophils (PMN) participate in the development of myocardial injury during ischaemia/reperfusion and granules released by human neutrophils contain proteases capable of activating prorenin in human plasma and can cleave angiotensin II directly from angiotensin I and angiotensinogen. The purpose of the present study was to investigate whether angiotensin converting enzyme (ACE)-inhibitors exert an in vitro effect on PMN degranulation. Isolated neutrophils were incubated with captopril, lisinopril, enalaprilat or ramiprilat and release of lysozyme and myeloperoxidase was measured from unstimulated and opsonised zymosan stimulated cells. All ACE inhibitors increased neutrophil myeloperoxidase release and lysozyme release by both unstimulated and stimulated cells. In the presence of saline unstimulated PMN released 4.48 +/- 0.68% and zymosan-stimulated cells released 7.28 +/- 0.76% of myeloperoxidase content and the enzyme release increased after incubation with captopril (5.55 +/- 0.71 and 8.74 +/- 0.72%), lisinopril (5.43 +/- 0.57 and 9.02 +/- 0.7%), enalaprilat (6.05 +/- 0.67 and 9.20 +/- 0.82%) and ramiprilat (5.82 +/- 0.69 and 9.26 +/- 0.74%), respectively. In the presence of saline unstimulated PMN released 16.71 +/- 1.28% and zymosanstimulated PMN released 34.42 +/- 1.71% of lysozyme content and the release increased after incubation with captopril (21.15 +/- 1.36 and 42.75 +/- 1.95%), lisinopril (23.95 +/- 1.26 and 39.23 +/- 1.94%), enalaprilat (21.34 +/- 1.32 and 41.59 +/- 1.99%) and ramiprilat (20.88 +/- 1.35 and 37.53 +/- 1.95%) by unstimulated PMN, respectively. The ACE-inhibitory effect of these drugs may therefore be decreased by stimulation of PMN degranulation and neutrophil-dependent angiotensin II forming pathway.

Intravenous isosorbide dinitrate inhibits neutrophil aggregation and plasma-mediated stimulation of superoxide anion production.

Polymorphonuclear neutrophils are known to be activated during myocardial ischaemia causing release of free oxygen radicals and capillary plugging by cell aggregates and therefore to exacerbate ischaemic myocardial injury. Nitric oxide has been shown to modulate neutrophil activation within the ischaemic myocardium and therefore reduce myocardial injury during ischaemia. Drugs that act as nitric oxide donors may therefore modify neutrophil activation. We evaluated the effect of intravenous treatment with isosorbide dinitrate on neutrophil aggregation and plasma-mediated stimulation of neutrophil superoxide anion production in patients with ischaemic heart disease. Samples were obtained from patients before treatment and 15 and 30 min after receiving intravenous isosorbide dinitrate. Isosorbide dinitrate decreased neutrophil aggregation visualized in whole blood (25.3 +/- 3.6, 19.0 +/- 2.6 and 18.5 +/- 2.6 per 300 cells, respectively, P < 0.01). When patient's plasma was incubated with neutrophils obtained from healthy donors, superoxide anion release was 18.99 +/- 6.23, 11.38 +/- 2.79 and 11.49 +/- 3.15 nmol O2-/10(6) cells, respectively (P < 0.01). Therefore, intravenous isosorbide dinitrate inhibited both plasma-mediated stimulation of neutrophil superoxide anion production and neutrophil aggregation.

Neutrophil adherence-augmenting and chemotactic plasma activities in acute myocardial infarction: effect of fibrinolytic treatment.

Polymorphonuclear neutrophils (PMNs) participate in the development of myocardial reperfusion injury during fibrynolytic treatment. In 40 patients with acute myocardial infarction, we evaluated the effect of streptokinase treatment on plasma activity augmenting PMN adherence and chemotactic plasma activity in peripheral venous blood with the use of neutrophils obtained from healthy donors. In all patients we observed the appearance of marked plasma chemotactic activity and plasma activity augmenting PMN adherence. Peak values of both plasma activities in the conventionally treated group were reached on the third day following the onset of symptoms. In streptokinase treated patients both plasma activities reached a peak on the second day after the onset of symptoms. Furthermore, streptokinase in vitro induced adherence of control PMNs in a dose-dependent manner, as well as increasing both chemotaxis and random migration of control cells. Thus, both chemotactic plasma activity and neutrophil adherence augmenting plasma activity may be used for monitoring the inflammatory response to myocardial infarction. However, during fibrynolytic treatment the presence of chemotactic stimuli in peripheral blood may be affected by streptokinase per se.

Interleukin-8 is not involved in the increased chemotactic activity of peripheral blood plasma during acute myocardial infarction.

Polymorphonuclear neutrophils (PMN) are known to participate in the development of tissue injury during myocardial infarction due to both free oxygen radicals release, as well as to their involvement in the "no-reflow" phenomenon. We have previously shown that peripheral blood plasma (obtained from patients with acute myocardial infarction) has chemotactic activity for PMN and is able to induce PMN adherence as well as superoxide anion production. To investigate whether interleukin-8 (IL-8/NAP-1), a potent chemotactic factor for PMN, is involved in plasma-mediated PMN stimulation, we measured plasma levels of IL-8 in five patients with transmural myocardial infarction with highly sensitive enzyme-linked immunosorbent assay (ELISA) using specific antibodies. Blood samples were taken immediately after patients' admission, within 15 and 30 min of treatment with intravenous nitrates, as well as after 1, 2, 3, and 7 days. All samples expressed IL-8 activity within the detection limit (0.4 ng/ml) as observed at the basal state. Thus, IL-8 may not be considered as responsible for the chemotactic activity in peripheral blood in patients with myocardial infarction.