Tomasz Siminiak

Neutrophil mediated myocardial injury

1. Activated polymorphonuclear neutrophils (PMN) were shown to exacerbate ischemic myocardial injury and their activation is modulated by complement system, platelet activating factor, arachidonic acid metabolites, adenosine and nitric oxide. 2. Mechanisms of injurious PMN effect on ischemic myocardium are related to both mechanical and biochemical processes. 3. Activated PMN aggregate and adhere to endothelium that results in capillary plugging and subsequent impairment of coronary blood flow as well as participating in the development of endothelial cell edema. 4. PMN-related biochemical damage of ischemic myocardium is a result of the release of cytotoxic free oxygen radicals and proteolytic enzymes as well as vasoconstrictor leukotriene B4 and leukotoxin.

Evidence for Plasma-Mediated Neutrophil Superoxide Anion Production during Myocardial Infarction

The participation of polymorphonuclear neutrophils (PMN) in the development of free-oxygen-mediated myocardial injury is well documented, but direct evidence that PMN-oriented stimuli released to the peripheral blood are able to stimulate PMN free oxygen radical production is missing. We have previously reported that peripheral blood plasma obtained from patients with acute myocardial infarction has chemotactic activity for neutrophils and augments PMN adherence. To investigate whether neutrophilic stimuli released to peripheral blood may induce PMN superoxide anion (O2-) production, we incubated PMN from healthy donors with plasma from patients with acute transmural infarction. PMN O2- production was measured by cytochrome c reduction. PMN O2- was higher under the influence of plasma obtained on the day of admission (24.66 +/- 12.41) and 1 day after onset of acute ischemia (22.91 +/- 10.37) as compared with those observed after incubation with saline (4.18 +/- 1.37; negative control) or zymosan-activated plasma (11.07 +/- 3.4; activated complement cascade positive control). In the following days, plasma-mediated PMN O2- decreased: 13.27 +/- 1.96; 12.37 +/- 3.54 and 8.18 +/- 1.56 after incubation with plasma obtained 2, 3 and 7 days after onset of symptoms, respectively. The results indicate an additional possibility of monitoring the inflammatory response to myocardial necrosis.

Effect of Selected Antiarrhythmic Drugs on the Superoxide Anion Production by Polymorphonuclear Neutrophils in vitro

The oxygen radicals produced by polymorphonuclear neutrophils (PMN) during ischemia and reperfusion play an important role in the development of arrhythmias. We investigated the influence of selected antiarrhythmic drugs on PMN superoxide anion production. Amiodarone, verapamil and propranolol significantly decreased the stimulated superoxide anion production, which may be an additional mechanism of their antiarrhythmic activity. The fast sodium channel inhibitors lidocaine, procainamide and mexiletine affected neither spontaneous nor stimulated superoxide anion production.

The effect of lidocaine on oxygen free radical production by polymorphonuclear neutrophils

During myocardial ischemia and subsequent reperfusion, activation of polymorphonuclear neutrophils occurs and results in an increased production of oxygen free radicals that participate in the generation of reperfusion arrhythmias. We investigated the effect of antiarrhythmic drug lidocaine on oxygen free radicals production by activated neutrophilsin vitro with a chemiluminescence assay. Lidocaine reduced lucigenin-amplified chemiluminescence related to the superoxide anion production but failed to affect hydrogen-peroxide dependent luminol chemiluminescence.

The influence of isosorbide dinitrate and molsidomine on migration of polymorphonuclear neutrophils in vivo

There is evidence that accumulation of polymorphonuclear neutrophils exacerbates injury to the tissues during acute myocardial infarction. To evaluate the influence of the vasodilator drugs, isosorbide dinitrate and molsidomine on migration of polymorphonuclear neutrophils, the skin chamber method was used. The number of neutrophils harvested from the chamber after oral treatment with isosorbide dinitrate increased from 27.65 +/- 9.02 X 10(6)/cm2 to 69.08 +/- 11.41 X 10(6)/cm2. Migration of neutrophils after molsidomine did not change significantly. Both drugs exert a similar effect on vascular smooth muscle cells. The difference in the influence on migration of granulocytes might be the result of an additional effect of molsidomine on formation of thromboxane and/or effects on the lipoxygenic pathway of arachidonic acid.

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 patients 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 fibrynolytic 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.

Vasodilator therapy enhances neutrophil tissue migration

Very little is known about the effect of vasoactive substances on migration of polymorphonuclear neutrophilsin vivo. We evaluated the effect of oral treatment with isosorbide dinitrate on neutrophil migration into a sterile skin inflammatory focus in man with the use of “skin chamber technique”. Isosorbide dinitrate increased the number of neutrophils harvested in the chamber as well as the “granulocyte clearance”. Thus, vasoactive agent may increase neutrophil extravasation and subsequent tissue migration.