dinoprost and linsidomine

Peroxynitrite is formed by the reaction of nitric oxide (NO) and superoxide. Since widespread peroxynitrite activity was observed during experimental allergic encephalomyelitis (EAE), the effect of this strong lipid-peroxidizing agent on myelin integrity was examined. Incubation of myelin suspensions with the peroxynitrite donor 3-morpholinosydnonimine (SIN-1) resulted in the formation of the lipid peroxidation product, malondialdehyde (MDA). MDA formation was inhibited in the presence of butylated hydroxytoluene, which interrupts the progression of the lipid peroxidation chain reaction. Superoxide dismutase inhibited the effect of SIN-1, which indicates a role for superoxide, and contradicts a role for its dismutation product, hydrogen peroxide. The latter was confirmed by the failure of the catalase to inhibit MDA formation. Neither NO nor superoxide alone induced significant MDA formation in myelin, indicating that peroxynitrite formation is required for myelin-lipid peroxidation. Interestingly, NO actually inhibited lipid peroxidation in myelin, as demonstrated using simple NO donors. On the other hand, the simultaneous production of superoxide, as achieved with the NO-donor SIN-1, negated the inhibitory effect of NO. Finally, the production of isoprostanes, novel products generated during lipid peroxidation, was examined. Peroxynitrite-induced peroxidation of myelin resulted in isoprostane formation. Furthermore, increased levels of F2-isoprostanes and neuroprostanes were observed in spinal cords of mice during early progressive stages of autoimmune encephalomyelitis.

Topics: Animals; Central Nervous System; Dinoprost; Encephalomyelitis, Autoimmune, Experimental; F2-Isoprostanes; Lipid Peroxidation; Mice; Molsidomine; Myelin Proteins; Myelin Sheath; Nitrates; Nitric Oxide; Nitric Oxide Donors; Oxidants; Penicillamine

Nitric oxide (NO) is synthesized by the rat ovary and a role in the follicular development, the ovulation, and the luteal formation has been postulated. The aims this study were to determine the activity of nitric oxide synthase (NOs) enzyme during the ovulatory process and to demonstrate the existence of a relationship between the ovarian NO production and the synthesis of prostaglandins (PGs) involved in the follicular rupture. Prepuberal rats treated with PMSG/hCG to induce ovulation were used. The NOs activity, measured by [(14)C]citrulline formation, showed an increase after PMSG administration and reached a maximum at 10 h after hCG injection. NOs activity remained high up to 24 h post ovulation. At 10 h after the hCG injection, the activity of Ca(2+)-dependent NOs (constitutive NOs) was similar to that seen at 0 h, and the activity of Ca(2+)-independent NOs (inducible NOs) increased from 14.4 to 51% of total activity. The in vitro ovarian production of PGE and PGF(2alpha) was inhibited by L-NAME and stimulated by 3-morpho-linosydnonimine (SIN-1), a NO donor. The in vivo production of ovarian prostaglandins was also inhibited by the intrabursal administration of two NOs inhibitors, N(G)-nitro-L-arginine methyl ester (L-NAME) and N(G)-monomethyl-L-arginine (L-NMMA). Our results suggest that the inducible NOs (iNOs) is the main isoform involved in the ovulatory process and that the NO produced stimulates the synthesis of both PGE and PGF(2alpha) from the cyclooxygenase pathway, to enhance the process of follicle rupture.

Topics: Animals; Chorionic Gonadotropin; Dinoprost; Enzyme Activation; Enzyme Inhibitors; Female; Gonadotropins, Equine; Molsidomine; NG-Nitroarginine Methyl Ester; Nitric Oxide; Nitric Oxide Donors; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; omega-N-Methylarginine; Ovary; Ovulation; Ovulation Induction; Prostaglandin-Endoperoxide Synthases; Prostaglandins E; Rats; Rats, Wistar

Many lines of evidence indicate that an increased pancreatic production of nitric oxide (NO) and prostaglandins (PGs) is found in the pancreas of streptozotocin-diabetic rats and that endothelins (ETs) are closely related to the nitridergic and prostanoid pathway in several tissues. In the present study the relationship between NO, ETs, and PGs has been explored in isolated pancreatic tissue from streptozotocin-diabetic rats. Pancreatic ET levels are higher in pancreatic tissues from diabetic (D) rats compared to control (C) animals. The addition of nitric oxide synthase (NOS) inhibitors (1 mM N(G)-nitro-l-arginine methyl ester, 600 microM N(G)-monomethyl-l-arginine) in the incubating medium reduces and NO donors (SIN-1, 300 microM spermine suppress, NONOate 100 microM) increases ET levels in pancreatic slices from C and D animals. PGE(2) (10(-7) M) increases and indomethacin (10(-6) M) decreases ET pancreatic production only in D but not in C tissues when added into the incubating bath. When tissues are incubated in the presence of endothelin 1 (ET-1) (10(-7) M), NOS activity is higher in C pancreas, while the ET-receptor antagonist bosentan (B) decreases NOS levels in D but not in C tissues. When pancreatic arachidonic acid (AA) conversion to prostaglandins was explored, ET-1 increased PGF(2alpha), PGE(2), and TXB(2) levels in C but not in D tissues. B abolishes TXB(2) increment due to the diabetic state, but failed in modulating AA conversion to 6-keto PGF(1alpha), PGF2(alpha) and PGE(2) in D pancreas. Our results show an alteration in AA metabolism, ET production, and NO increment associated with pancreatic damage due to streptozotocin.

Topics: Animals; Arachidonic Acid; Diabetes Mellitus, Experimental; Dinoprost; Dinoprostone; Endothelin-1; Endothelins; Male; Molsidomine; NG-Nitroarginine Methyl Ester; Nitric Oxide; Nitric Oxide Donors; Nitric Oxide Synthase; Nitrogen Oxides; omega-N-Methylarginine; Pancreas; Rats; Rats, Wistar; Spermine; Streptozocin; Thromboxane B2

Improvements in myocardial protection may include the continuous delivery of normothermic blood cardioplegia. Technical aids are required for optimal visualization of the operative field during the performance of coronary anastomoses if cardioplegia is to be given continuously or during minimally invasive operations. However, the effects of the different hemostatic devices on coronary endothelial function are unknown.. We compared the effects on endothelial function of two commonly used hemostatic techniques, coronary clamping and gas jet insufflation, with those of a technique using extravascular balloon occlusion to mimic systolic luminal closure by the surrounding myocardium. The three techniques were applied for 15 minutes on porcine epicardial coronary arteries from explanted hearts. For coronary clamping, standard bulldog clamps were used. Gas jet insufflation was applied by blowing oxygen (12 L/min) tangentially at a 45-degree angle 1 cm away from a 3-mm arteriotomy. Extravascular balloon occlusion was achieved with a needle-tipped silicone loop, the midportion of which, once positioned beneath the coronary artery, was inflated to push a myocardial "cushion" against the back of the vessel until its occlusion. Control rings were taken from the same coronary artery. The endothelial function of control and instrumented arterial rings was then studied in organ chambers filled with modified Krebs-Ringer bicarbonate solution.. Contractions to potassium chloride and prostaglandin F2 alpha and endothelium-independent relaxation to sin-1, a nitric oxide donor, were unaffected in all groups. Endothelium-dependent relaxation to serotonin was impaired after clamping and preserved after gas jet insufflation and extravascular balloon occlusion. Maximal endothelium-dependent relaxation to serotonin was as follows: for coronary clamping, 63% +/- 6% versus 87% +/- 3% in controls; for gas jet insufflation, 67% +/- 12% versus 88% +/- 7%; and for extraluminal balloon occlusion, 79% +/- 6% versus 85% +/- 5%.. Whereas commonly used hemostatic devices may impair endothelial function, extravascular balloon occlusion appears to achieve effective hemostasis while preserving endothelial integrity.

Topics: Animals; Catheterization; Constriction; Coronary Vessels; Dinoprost; Endothelium, Vascular; Heart Arrest, Induced; Hemostasis, Surgical; In Vitro Techniques; Minimally Invasive Surgical Procedures; Molsidomine; Myocardial Revascularization; Potassium Chloride; Serotonin; Surgical Instruments; Swine; Vasoconstriction; Vasodilator Agents

Topics: Arachidonic Acids; Dinoprost; Humans; Kinetics; Lipoproteins, LDL; Molsidomine; Nitrates; Oxidation-Reduction; Platelet Aggregation Inhibitors

Experiments were designed to compare the relaxing activities of the new sydnonimine C87-3754 with SIN-1 in arteries and veins of the dog, and to determine whether C87-3754 can prevent endothelium-dependent contractions. Rings of coronary and femoral arteries, and saphenous veins were suspended in organ chambers for the measurement of changes in isometric tension. SIN-1 and C87-3754 evoked concentration-dependent relaxations in all rings of blood vessels contracted with a submaximal concentration of either prostaglandin F2 alpha, endothelin-1, phenylephrine, or norepinephrine. In both arteries and veins, the concentration-relaxation curves to C87-3754 were shifted significantly to the right (by two to three logarithmic units) of that to SIN-1. The presence of endothelium significantly inhibited the relaxations to SIN-1 but did not affect those to C87-3754. The treatment of coronary arteries with methylene blue or oxyhemoglobin significantly impaired the relaxation to SIN-1 and C87-3754. Neither C87-3754 nor its prodrug pirsidomine (CAS 936) affected the membrane potential in coronary arteries. The endothelium-dependent contractions evoked by nitro L-arginine, arachidonic acid, and the calcium ionophore A23187 in basilar arteries of the dog were inhibited by C87-3754. These results indicate that the sydnonimine C87-3754 is a dilator of both arterial and venous smooth muscle, and can prevent endothelium-mediated contractions in cerebral arteries of the dog. The inhibition of vascular tone is likely to involve the activation of soluble guanylate cyclase, causing enhanced production of cyclic guanosine monophosphate in the smooth muscle without a change in membrane potential.

Topics: Animals; Dinoprost; Dogs; Drug Interactions; Electrophysiology; Endothelium, Vascular; Female; Male; Membrane Potentials; Molsidomine; Muscle Relaxation; Muscle, Smooth, Vascular; Sydnones; Vasodilator Agents

1. Previous studies, demonstrated that endothelium-dependent relaxations which are resistant to nitro-L-arginine (an inhibitor of nitric oxide synthase) are accompanied by membrane hyperpolarization in the porcine coronary artery. The present experiments were designed to characterize further this type of endothelium-dependent relaxation in response to bradykinin by measuring isometric force in isolated rings of that artery. The experiments were performed in the presence of indomethacin to rule out vasoactive prostanoids. 2. Bradykinin induced comparable endothelium-dependent relaxations of proximal and distal rings of porcine coronary arteries contracted with prostaglandin F2 alpha in the presence of nitro-L-arginine. 3. Bradykinin and SIN 1 (a donor of nitric oxide) reduced contractions induced by prostaglandin F2 alpha in an additive fashion in the presence of nitro-L-arginine. 4. Bradykinin (in the presence of nitro-L-arginine) relaxed the tissues contracted with tetraethylammonium, prostaglandin F2 alpha, phorbol 12, 13-diacetate or endothelin, with similar pD2 values. 5. The time course of the relaxations induced by bradykinin (in the presence of nitro-L-arginine) and UK14304 (an alpha 2-adrenoceptor agonist, in the absence of the inhibitor of nitric oxide synthase) were comparable. 6. These results suggest that, in the porcine coronary artery, nitro-L-arginine-resistant relaxations (a) are distributed similarly in the proximal and distal parts of the artery, (b) contribute to inhibition of vascular smooth muscle with nitric oxide in an additive fashion, (c) occur during contractions induced by various contractile agents and (d) do not precede those mediated by nitric oxide.

Topics: Animals; Arginine; Bradykinin; Coronary Vessels; Dinoprost; Endothelium, Vascular; In Vitro Techniques; Molsidomine; Muscle Relaxation; Muscle, Smooth, Vascular; Nitric Oxide; Nitroarginine; Swine; Vasodilation; Vasodilator Agents

Human epicardial coronary arteries were obtained from the hearts of 15 patients who received cardiac transplantation for cardiomyopathy. Transverse strips of these arteries were mounted in organ baths for isometric tension recording. The arteries were constricted with prostaglandin F2 alpha and then exposed to the endothelium-dependent relaxants substance P (1 nM), bradykinin (1 nM-1 microM), and the Ca2+ ionophore A23187 (1 nM-1 microM). The effects of the endothelium-independent relaxants glyceryl trinitrate (1 nM-10 microM) and SIN-1, the active metabolite of molsidomine (1 nM-10 microM), were also tested. In control strips of human coronary arteries, all vasodilators caused concentration-dependent relaxations. Pretreatment of human coronary arteries with glyceryl trinitrate (0.5 mM for 60 min) shifted the concentration-response curve to glyceryl trinitrate to the right by a factor of approximately 800 (increase in EC50 from 10 nM to 8 microM). In contrast, endothelium-dependent relaxations to substance P, bradykinin, and A23187 and relaxations to SIN-1 were not changed significantly. Previous exposure of human coronary arteries to SIN-1 (0.5 mM for 60 min) did not modify relaxations to any of the agents tested. Our results show that (a) the responsiveness to SIN-1 is not modified in nitrate-tolerant strips of human coronary arteries, (b) prolonged exposure of human coronary arteries to SIN-1 does not cause tolerance, and (c) endothelium-dependent relaxations are not influenced by exposure of human coronary arteries to either glyceryl trinitrate or SIN-1.

Topics: Adult; Analysis of Variance; Bradykinin; Calcimycin; Dinoprost; Drug Tolerance; Humans; In Vitro Techniques; Middle Aged; Molsidomine; Myocardial Contraction; Nitroglycerin; Substance P; Vasodilator Agents

The effects of SIN-1 were investigated on the electrical and mechanical properties of vascular smooth muscle cells of the canine saphenous vein. Isolated tissues with or without endothelium were contracted with norepinephrine, prostaglandin F2 alpha or endothelin. SIN-1 and nitric oxide caused comparable concentration-dependent relaxations in rings with and without endothelium irrespective of the contracting agent. The relaxations to both SIN-1 and nitric oxide were inhibited by methylene blue. SIN-1 (up to 10(-5) M) and nitric oxide (up to 10(-5) M) did not alter membrane potential. The excitatory junction potentials and the slow depolarization generated by perivascular nerve stimulation were not affected by SIN-1 or nitric oxide. These results suggest that SIN-1 relaxes vascular smooth muscle by increasing the production of cyclic GMP without changing the membrane potential. In addition, SIN-1 does not modify peripheral adrenergic neurotransmission.

Topics: Analysis of Variance; Animals; Dinoprost; Dogs; Endothelins; Female; In Vitro Techniques; Male; Membrane Potentials; Methylene Blue; Molsidomine; Muscle, Smooth, Vascular; Nitric Oxide; Norepinephrine; Saphenous Vein; Sympathetic Nervous System; Synaptic Transmission; Vasodilator Agents

Experiments were designed to compare the vasodilator properties of SIN-1, the active metabolite of molsidomine, with nitric oxide (NO) and sodium nitroprusside. Rings of canine femoral arteries and veins with and without endothelium were suspended in organ chambers for the measurement of isometric force. SIN-1 and sodium nitroprusside relaxed rings of blood vessels in the presence and in the absence of the endothelium. However, these relaxations were reduced by the endothelial cells in arteries contracted with endothelin and in veins contracted with prostaglandin F2 alpha. In the arteries, SIN-1, sodium nitroprusside, and NO were equipotent in relaxing rings without endothelium contracted with either norepinephrine or prostaglandin F2 alpha; NO was less potent than the other two vasodilators when the arteries were contracted with endothelin. In the veins without endothelium, the potency of the three nitrovasodilators was comparable; the veins were more sensitive to the effects of the dilators when contracted with prostaglandin F2 alpha than with either endothelin or norepinephrine. These results indicate that SIN-1, sodium nitroprusside, and NO are potent dilators of arterial and venous smooth muscle, and that the potency of the dilators can be altered by endothelial cells and the contractile agonist differentially in arteries and veins.

Topics: Analysis of Variance; Animals; Dinoprost; Dogs; Endothelins; Endothelium, Vascular; Femoral Artery; Femoral Vein; In Vitro Techniques; Molsidomine; Muscle Relaxation; Nitric Oxide; Nitroprusside; Norepinephrine; Vasodilator Agents