6-ketoprostaglandin-f1-alpha and defibrotide

Defibrotide is a polynucleotide extracted from mammalian lung, which shows antithrombotic and anti-ischaemic activity in animals, probably related to stimulation of fibrinolysis and/or enhancement of prostacyclin production. The effect of a single infusion of defibrotide on fibrinolysis and the levels of certain prostanoids in man has been investigated in a cross-over double-blind placebo-controlled study. Evaluation of changes in fibrinolysis was difficult because of the spontaneous activation observed after placebo. However, the fast-acting plasminogen activator inhibitor was decreased only at end of the defibrotide infusion, suggesting a moderate profibrinolytic effect superimposed on the spontaneous activation. There was a marked and prolonged elevation of the plasma level of 6-keto-PGF1 alpha, the stable metabolite of prostacyclin. In collagen stimulated whole blood, both 6-keto-PGF1 alpha and prostaglandin E2 production were also greatly increased, with no consistent indication of inhibition of thromboxane B2. It is suggested that defibrotide stimulates prostacyclin and prostaglandin E2 production by leucocytes or via platelet/leukocyte interactions. The effects observed here should be useful in guiding subsequent clinical trials.

Topics: 6-Ketoprostaglandin F1 alpha; Dinoprostone; Double-Blind Method; Female; Fibrinolysis; Fibrinolytic Agents; Humans; Infusions, Intravenous; Male; Polydeoxyribonucleotides; Random Allocation; Thromboxane B2

In a previous paper we gave evidence that chronic oral defibrotide antagonizes the noxious effect of developing atherosclerosis in the cardiovascular system. In the present paper we give evidence that defibrotide is still capable of exerting beneficial effects on cardiovascular function once atherosclerosis is established. In fact, there was statistically significant amelioration by defibrotide infusion in the following, all of which were hampered by established atherosclerosis: in rabbit aorta relaxation to acetylcholine, prostaglandin E2, and 6-keto-prostaglandin F1alpha generation from rabbit aortas, rabbit heart left ventricular end-diastolic pressure, coronary perfusion pressure, and left ventricular developed pressure, vasopressor activity of acetylcholine and endothelin-1 on coronary perfusion pressure, and 6-keto-prostaglandin F1alpha generation from the rabbit heart. Since prostacyclin takes part in NO generation, is cellular protective, and inhibits 5-lipoxygenase product synthesis, its increase, caused by defibrotide, could explain defibrotide cardioprotective activity. Prostacyclin activity could be backed by prostaglandin E2, another cardioprotective prostaglandin.

Topics: 6-Ketoprostaglandin F1 alpha; Acetylcholine; Animals; Aorta; Arteriosclerosis; Blood Pressure; Body Weight; Cardiovascular Physiological Phenomena; Cholesterol, Dietary; Dinoprostone; Endothelin-1; Fibrinolytic Agents; Heart; In Vitro Techniques; Lipids; Male; Muscle Contraction; Muscle, Smooth, Vascular; Organ Size; Platelet Aggregation Inhibitors; Polydeoxyribonucleotides; Rabbits; Reperfusion; Ventricular Function, Left

The aim of the present work was to assess if the cardioprotective drug defibrotide could counteract the hypercholesterolemia noxious effects on cardiovascular function. Aortas and hearts from normal- or cholesterol-fed rabbits, treated or not with chronic oral defibrotide (100 mg/kg/day) for 45 days, were used in in vitro tests throughout the experiment. Hypercholesterolemia worsened: aorta stickiness toward polymorphonuclear leukocytes, aorta relaxation to acetylcholine, heart left ventricular end-diastolic pressure and coronary perfusion pressure, heart left ventricular diastolic pressure, acetylcholine and endothelin-1 activity on coronary perfusion pressure, and heart generation of 6-Keto-prostaglandin F1alpha. Oral defibrotide counteracted and/or obliterated the above hypercholesterolemia noxious effects. Particularly, oral defibrotide counteracted the parameters associated with early endothelial cell disfunction: that is, increased adherence of leukocytes to endothelium and endothelial vasorelaxation induced by acetylcholine, which acts through the release of endothelium-derived relaxing factor. These activities of defibrotide are probably exerted through the increased generation of prostacyclin. The fact that acetylcholine induced vasorelaxation is partially protected by oral defibrotide points to a partial rescue of endothelial ability to generate endothelium-derived relaxing factor, as acethylcoline acts through the release of endothelium-derived relaxing factor, by defibrotide itself. Defibrotide's endothelial protection could, in turn, explains why defibrotide protected cardiovascular function. This is not surprising as, in a few cases, endothelial dysfunction, observed in hypercholesterolemia, was found to be prevented or reversed, pharmacologically, by PN-2001-10, a calcium channel blocker, dipyridamole, and lovastatin.

Topics: 6-Ketoprostaglandin F1 alpha; Administration, Oral; Animals; Aorta; Blood Pressure; Cholesterol, Dietary; Fibrinolytic Agents; Heart; Hypercholesterolemia; Myocardium; Polydeoxyribonucleotides; Rabbits; Vasoconstriction; Ventricular Function, Left

The pathogenesis of frostbite injury has not been completely elucidated although the available evidence suggests it is an inflammatory reaction following reperfusion injury. Defibrotide given i.p. at 40 mg/kg/ day for three days to rabbits, the ears of which were subjected to frostbite, decreased the presence of inflammatory cells (mast cells -76%; neutrophils -40.4%) and increased prostaglandin I2 (PGI2) (as 6-Keto-PGF1 alpha) in the involved skin. Thromboxane A2 (TxA2) (as TxB2) was unaffected. These data strengthen the view that an inflammatory process is the underlying cause of frostbite injury and that Defibrotide is active in pathological situations involving an inflammatory process like in frostbite.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Female; Fibrinolytic Agents; Frostbite; Leukocyte Count; Male; Mast Cells; Neutrophils; Platelet Aggregation Inhibitors; Polydeoxyribonucleotides; Rabbits; Skin; Thromboxane A2

Several attempts have been undertaken to reduce the severity of ischemic myocardial injury by exogenous administration of eicosanoids and by modification of endogenous eicosanoid production. The present study investigates whether defibrotide, a compound that stimulates endogenous prostacyclin (PGI2), has a beneficial effect in experimental ischemic myocardial injury. Anesthetized, open-chest minipigs were subjected to 1 h of coronary artery occlusion, followed by 3 h of reperfusion. Defibrotide (32 mg/kg x h) or its vehicle were infused i.v. throughout the experiment. Defibrotide increased cardiac PGI2 formation 3- to 4-fold greater than control (P < .05). Thromboxane levels remained unchanged. Irreversible ischemic injury, as identified by negative tetrazolium staining, amounted to 44 +/- 6% of the area at risk in pigs receiving vehicle but was reduced to 23 +/- 4% by defibrotide (P < .05). This reduced tissue injury in defibrotide-treated pigs was associated with improved functional recovery (left ventricular pressure, + dP/dtmax), during early reperfusion. Recovery did not occur in vehicle-treated pigs. Collagen (2 micrograms/ml)-induced platelet aggregation ex vivo was increased in vehicle-treated pigs during ischemia and reperfusion, but not in animals treated with defibrotide. Polymorphonuclear neutrophil leukocyte accumulation in the ischemic border zone was reduced from 59 +/- 17 cells/mm2 in vehicle-treated pigs to 17 +/- 9 cells/mm2 by defibrotide (P < .05). Pretreatment of the animals with indomethacin (3 mg/kg) prevented the reduction of infarct size and polymorphonuclear neutrophil leukocyte infiltration by defibrotide. Indomethacin increased infarct size in vehicle- and defibrotide-treated pigs by 71 and 59%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Blood Platelets; Cyclooxygenase Inhibitors; Disease Models, Animal; Epoprostenol; Female; Granulocytes; Indomethacin; Leukocyte Count; Male; Myocardial Infarction; Myocardial Ischemia; Myocardial Reperfusion Injury; Myocardium; Neutrophils; Platelet Count; Polydeoxyribonucleotides; Prostaglandins; Stimulation, Chemical; Swine; Swine, Miniature; Thromboxane A2; Ventricular Function, Left

Topics: 6-Ketoprostaglandin F1 alpha; Adult; Blood; Blood Coagulation; Blood Coagulation Tests; Blood Proteins; Fatty Acids, Nonesterified; Female; Fibronectins; Humans; Infusions, Intravenous; Male; Peptidyl-Dipeptidase A; Polydeoxyribonucleotides

Prostacyclin (PGI2) improves regional contractility of postischemically dysfunctional ("stunned") myocardium. We determined whether defibrotide, a fraction of mammalian DNA known to stimulate endogenous formation of PGI2, also improves contractile recovery of stunned myocardium. Anesthetized, open-chest minipigs were subjected to coronary occlusion of 5 min (left anterior descending branch, LAD) followed by 120 min of reperfusion. The animals were treated with defibrotide (32 mg x kg-1 x h-1, intravenously, i.v.) or vehicle throughout the experimental period. Defibrotide improved regional contractility in the ischemic reperfused area from 30 (vehicle) to 78% of the preischemic control without altering the contractility of nonischemic myocardium. Transcardiac PGI2 formation, determined from the difference between coronary venous and arterial plasma concentrations, was elevated from 437 (preischemic control) to 869 pmol x l-1 in defibrotide-treated animals, but was unchanged in the vehicle-treated and a sham-operated group. Thromboxane A2 (TXA2) release was not modified. Defibrotide reduced ischemia-induced formation of platelet aggregates but did not affect the activity of polymorphonuclear neutrophil granulocytes. The data demonstrate an improvement of contractile recovery from stunning by defibrotide that may be related to an inhibition of ischemia-induced platelet activation and (or) membrane protection owing to enhanced transcardiac formation of PGI2.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Blood Platelets; Coronary Vessels; Epoprostenol; Female; Fibrinolytic Agents; Heart; Hemodynamics; Male; Myocardial Contraction; Myocardial Infarction; Myocardial Reperfusion; Neutrophils; Platelet Count; Polydeoxyribonucleotides; Stimulation, Chemical; Swine; Swine, Miniature; Thromboxane B2; Time Factors

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Coronary Disease; Epoprostenol; Fibrinolytic Agents; In Vitro Techniques; Myocardial Reperfusion Injury; Platelet Activating Factor; Polydeoxyribonucleotides; Rabbits

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Aorta, Thoracic; Dinoprostone; In Vitro Techniques; Male; Polydeoxyribonucleotides; Prostaglandins; Rabbits; Rats; Rats, Inbred Strains

Spirals of human saphenous veins (HSV), mounted in a 5 ml organ bath containing Krebs-Henseleit solution (37 degrees C), when kept in contact with defibrotide (100-200 ug/ml) for 15 min, enhance (2 and 3 fold) their own basal release of 6-keto-PGF 1 alpha (61 +/- 1.3 pg/mg w.t. n = 12). The phenomenon was long lasting upon repeated washing and sensitive to indomethacin (1 ug/ml). Endothelin-1 (ET-1, 20-40 ng) induced a sustained contraction of HSV and concomitantly released from the venous tissue a proportional amount of 6-keto-PGF 1 alpha. Indomethacin (1 ug/ml), by inhibiting cyclo-oxygenase enzyme, potentiated the contractile activity of ET-1 in HSV whereas exogenous PGE2 (20 ng/ml) considerably reduced the tension developed by the peptide on this venous tissue. Defibrotide (200 ug/ml), by releasing 6-keto-PGF 1 alpha, and other vasoactive prostaglandins, antagonized the contractile effect ET-1 (20 ng) in HSV. This data indicates that the eicosanoid metabolism is involved in the modulation of the potent vasoconstrictor effect of ET-1 in HSV and that PGI2-releaser, such as defibrotide, may have therapeutical value against immoderate changes of venous tone.

Topics: 6-Ketoprostaglandin F1 alpha; Adolescent; Adult; Cyclooxygenase Inhibitors; Dinoprostone; Endothelins; Epoprostenol; Female; Humans; Indomethacin; Male; Middle Aged; Muscle Contraction; Muscle, Smooth, Vascular; Polydeoxyribonucleotides; Saphenous Vein; Vasoconstriction

Defibrotide is known to enhance prostacyclin (PGI2) release from the vascular endothelium. We investigated the vasoactive effects of defibrotide in isolated rat hearts perfused at constant flow subjected to ischaemia and reperfusion. Defibrotide at 10 or 100 micrograms/ml did not exert any direct vasoactive effect on normal rats hearts. However, ischaemia and reperfusion resulted in an impaired vasodilation to acetylcholine, an endothelium-dependent vasodilator. In contrast, the vasodilator response to the endothelium-independent dilator, nitroglycerin, was unaffected. Defibrotide, at 10 or 100 micrograms/ml, markedly restored the vasodilation to acetylcholine 10 nmol/l to 1 mumol/l (P less than 0.01) without influencing the vasodilator response to nitroglycerin (2 to 200 micrograms/l). Haemoglobin (150 nmol/l) inhibited the dilation to acetylcholine in response to defibrotide. However, no evidence of PGI2 release was observed with acetylcholine-induced vasodilation in the presence or absence of defibrotide. Additionally, 10-100 micrograms/ml of defibrotide did not significantly decrease superoxide radicals generated by a xanthine-xanthine oxidase synthetic system under conditions in which superoxide dismutase was effective. Thus, defibrotide appears to exert an endothelium-protective effect preserving endothelium-derived relaxing factor (EDRF) without directly scavenging free signals.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; 6-Ketoprostaglandin F1 alpha; Acetylcholine; Animals; Coronary Disease; Coronary Vessels; Endothelium, Vascular; Epoprostenol; Fibrinolytic Agents; In Vitro Techniques; Male; Myocardial Reperfusion; Nitric Oxide; Nitroglycerin; Polydeoxyribonucleotides; Prostaglandin Endoperoxides, Synthetic; Rats; Rats, Inbred Strains; Superoxide Dismutase; Superoxides

In the past few years there has been increasing interest in the role of the vascular endothelium as an active modulator of biological responses. Endothelial cells exert antithrombotic activity by the release of prostacyclin [23] and adenine nucleotides [16], the availability on the cell surface of heparin-like substances [3], and thrombomodulin-mediated activation of protein C [8]. In addition, endothelium is involved in the regulation of fibrinolysis by releasing soluble factors, such as tissue plasminogen activator (tPA; [10]) and plasminogen activator inhibitor (PAI; [22, 11]), as well as in the control of vascular responsiveness by the production of smooth muscle relaxing and contracting factors. Endothelial cells have also been shown to synthesize and to express procoagulant activities [18]. Many data on endothelial cell functions has been obtained from two experimental models, namely endothelial cell cultures and perfused segments of animal and human vessels. Both are subject to methodological criticism since they only represent in part in vivo conditions, and the necessary experimental manipulations and laboratory procedures greatly modify the naturally occurring cellular functions. In order to overcome such difficulties as far as possible, a new in vivo model has been employed to provide easily assessable and reliable data on the properties of endothelial cells in man. A venous segment was isolated functionally by cannulating a dorsal vein in the hand and a cubital vein in the same arm. Changes observed ex vivo in blood from the cubital vein following infusion into the hand vein of an active drug, can mainly be attributed to its local effect on the venous wall. At the same time, a cubital vein in the other arm was cannulated in order to provide information to distinguish systemic from regional effects.

Topics: 6-Ketoprostaglandin F1 alpha; Adult; Dose-Response Relationship, Drug; Endothelium, Vascular; Female; Fibrinolysis; Fibrinolytic Agents; Fibronectins; Hand; Humans; Male; Models, Biological; Peptidyl-Dipeptidase A; Plasminogen Inactivators; Polydeoxyribonucleotides; Time Factors; Tissue Plasminogen Activator

Topics: 6-Ketoprostaglandin F1 alpha; Angiography; Arteriosclerosis; Cyclic AMP; Female; Fibrinolytic Agents; Humans; Male; Middle Aged; Physical Exertion; Polydeoxyribonucleotides; Thromboangiitis Obliterans; Thromboxane B2

Patients were treated with defibrotide (3 X 200 mg/day) for 7 days. Plasma PGI2 and TXB2 levels were measured by RIA using EDTA-aspisol as anticoagulant and cyclooxygenase inhibitor. Isolated platelet c-AMP levels were also determined by RIA, using EDTA-dipyridamole as anticoagulant and phosphodiesterase inhibitor. Blood PGI2 levels were found to increase significantly upon treatment while the increase in TXB2 levels was not significant. Blood PGI2/TXB2 ratio increased 51%, 30 min after intravenous injection and it remained 28% higher during therapy than the predrug blood level. Significantly higher platelet c-AMP levels were also obtained after the injection of drug (0.02 less than p less than 0.05).

Topics: 6-Ketoprostaglandin F1 alpha; Arteriosclerosis; Blood Platelets; Cyclic AMP; Fibrinolytic Agents; Humans; Malondialdehyde; Platelet Aggregation; Polydeoxyribonucleotides; Prostaglandins; Thromboxane B2; Time Factors