[Potentiation of activation of soluble guanylate cyclase by YC-1, NO-donors and increase of the synergistic effect of YC-1 on NO-dependent activation of the enzyme by 1,2,3-triazolyl-1,2,5-oxadiazole derivatives].

The influence of (1H-1,2,3-triazol-1-yl)-1,2,5-oxadiazole derivatives: 4-amino-3-(5-methyl-4- ethoxycarbonyl-(1H-1,2,3-triazol-1-yl)-1,2,5-oxadiazole (TF4CH3) and 4,4'-bis(5-methel-4-ethoxycarbonyl-1H- 1,2,3-triazol-1-yl)-3,3'-azo-1,2,5-oxadiazole (2TF4CH3) on stimulation of human platelet soluble guanylate cyclase by YC-1, NO-donors (sodium nitroprusside, SNP, and spermine NONO) and on a synergistic increase of NO-dependent enzyme activation in the presence of YC-1 has been investigated. Both compounds increased guanylate cyclase activation by YC-1, potentiated guanylate cyclase stimulation by NO-donors and increased the synergistic effect of YC-1 on NO-dependent activation of soluble guanylate cyclase. The similarity in the properties of the examined TF4CH3 and 2TF4CH3 with that of YC-1 and the possible mechanism underlying the revealed properties of compounds used are discussed.

[The history of renalase from amine oxidase to a a-NAD(P)H-oxidase/anomerase].

Renalase is a recently discovered secretory protein, which plays a certain (still poorly understood) role in regulation of blood pressure. The review summarizes own and literature data accumulated since the first publication on relanase (2005). Initial reports on FAD-dependent amine oxidase activity of this protein were not confirmed in independent experiments performed in different laboratories. In addition, proposed amine oxidase activity of circulating extracellular renalase requires the presence of FAD, which has not been detected either in blood or urinary renalase. Moreover, renalase excreted into urine lacks its N-terminal peptide, which is ultimately needed for accommodation of the FAD cofactor. Results of the Aliverti's group on NAD(P)H binding by renalase and weak diaphorase activity of this protein stimulated further studies of renalase as NAD(P)H oxidase catalyzing reaction of catecholamine co-oxidation. However, physiological importance of such extracellular catecholamine-metabolizing activity (demonstrated in one laboratory and not detected in another laboratory) remains unclear due to existence of much more active enzymatic systems (e.g. neutrophil NAD(P)H oxidase, xanthine oxidase/xanthine) in circulation, which can perform such co-oxidation reactions. Recently a-NAD(P)H oxidase/anomerase activity of renalase, which also pomotes oxidative conversion of b-NADH isomers inhibiting activity of NAD-dependent dehydrogenases, has been described. However, its possible contribution to the antihypertensive effect of renalase remains unclear. Thus, the antihypertensive effect of renalase still remains a phenomenon with unclear biochemical mechanim(s) and functions of intracellular and extracellular (circulating) renalases obviously differ.

[Potentiation of NO-dependent activation of soluble guanylyl cyclase by 5-nitroisatin and antiviral preparatation arbidol].

Isatin (indole-dione) is an endogenous indole that exibits a wide range of biological and physiological activity. The influence of isatin derivatives 5-nitroisatin and arbidol (an antiviral preparatation) on spermine NONO-induced activation of human platelet soluble guanylyl cyclase was investigated. 5-nitroistnin and arbidol had no effect on basal activity, but synergistically increased in a concentration-dependent manner the spermine NONO-induced activation of this enzyme. 5-Nitroisatin and arbidol, like YC-1, sensitized guanylyl cyclase towards nitric oxide (NO) and produced a leftward shift of the spermine NONO concentration response curve. At the same time both compounds used did not influence the activation of guanylyl cyclase by YC-1 and did not change the synergistic increase of spermine NONO-induced activation of soluble guanylyl cyclase in the presence of YC-1. This suggests that 5-nitroisanin and arbidol did not compete with YC-1. Addition of isatin did not change the synergistic increase in the spermine NONO-induced guanylyl cyclase activation by 5-nitroisatin and arbidol and did not influence a leftward shift of spermine NONO concentration response curve produced by these compounds. These data suggest lack of competitive interaction between isatin and both its derivatives used.

[Soluble guanylate cyclase in the molecular mechanism underlying the therapeutic action of drugs].

The influence of ambroxol--a mucolytic drug--on the activity of human platelet soluble guanylate cyclase and rat lung soluble guanylate cyclase and activation of both enzymes by NO-donors (sodium nitroprusside and Sin-1) were investigated. Ambroxol in the concentration range from 0.1 to 10 microM had no effect on the basal activity of both enzymes. Ambroxol inhibited in a concentration-dependent manner the sodium nitroprusside-induced human platelet soluble guanylate cyclase and rat lung soluble guanylate cyclase with the IC50 values 3.9 and 2.1 microM, respectively. Ambroxol did not influence the stimulation of both enzymes by protoporphyrin IX. The influence of artemisinin--an antimalarial drug--on human platelet soluble guanylate cyclase activity and the enzyme activation by NO-donors were investigated. Artemisinin (0.1-100 microM) had no effect on the basal activity of the enzyme. Artemisinin inhibited in a concentration-dependent manner the sodium nitroprusside-induced activation of human platelet guanylate cyclase with an IC50 value 5.6 microM. Artemisinin (10 microM) also inhibited (by 71 +/- 4.0%) the activation of the enzyme by thiol-dependent NO-donor the derivative of furoxan, 3,4-dicyano-1,2,5-oxadiazolo-2-oxide (10 microM), but did not influence the stimulation of soluble guanylate cyclase by protoporphyrin IX. It was concluded that the sygnalling system NO-soluble guanylate cyclase-cGMP is involved in the molecular mechanism of the therapeutic action of ambroxol and artemisinin.

[Inhibition of no-dependent soluble human platelet guanylate cyclase by isatin].

Isatin (indole-dione-2,3) is an endogenous indole that exhibits a wide spectrum of biological and pharmacological activities. Physiologically relevant concentrations of isatin (ranged from 1 nM to 10 M) did not influence basal activity of soluble human platelet guanylate cyclase (sGC), but caused a bell-shaped inhibition of the NO-activated enzyme. Inhibition of the NO-dependent activation by isatin did not depend on a chemical nature of the NO donors. The inhibitory effects of ODC (a heme-dependent inhibitor of sGC) and isatin were non-additive suggesting that the inhibitory effect of isatin may involve the heme binding domain (possibly heme iron) and experiments with hemin revealed some isatin-dependent changes in its spectrum. Isatin also inhibited sGC activation by the allosteric activator YC-1. It is suggested that the bell shaped inhibition of the NO-dependent activation of sGC by isatin may be attributed to complex interaction of isatin with the heme binding domain and the allosteric YC-1-binding site of sGC.

[Potentiation of nitric oxide-dependent activation of soluble guanylate cyclase by levomycetin, tetracycline, and oxolin].

The influence of antibiotics laevomycetin and tetracycline and the antivirus agent oxolin on the activity of human platelet soluble guanylate cyclase, the stimulation of the enzyme by NO-donors (sodium nitroprusside (SNP) and spermine nanoate (spermine NONO)) and the combination of spermine NONO and YC-1 was investigated. All preparations used in the concentration range 0,1-10 mM had no effect on the basal activity of guanylate cyclase but potentiated the SNP-induced activation of this enzyme. All preparations used synergistically increased (similar to YC-1) spermine NONO-induced activation of soluble guanylate cyclase. At the same time these compounds did not produce the leftward shift of spermine NONO concentration response curve characteristic for YC-1. Moreover, all compounds used did not influence the leftward shift of spermine NONO concentration response curve obtained in the presence of YC-1. This demonstrated that there was no competition between YC-1 and the drugs for interaction with the enzyme. The revealed regulatory phenomen of laevomycetin, tetracycline and oxolin to increase synergistically NO-dependent activation of soluble guanylate cyclase may cause additional pharmacological effects during prolong treatment by these drugs. This fact is necessary taking into account.

[YC-1-like potentiation of nitric oxide-dependent activation of soluble guanylyl cyclase by adrenochrome].

The influence of adrenochrome and YC-1 on spermine NONO-induced activation of human soluble guanylyl cyclase was investigated. Adrenochrome (0.1-10 microM) had no effect on the basal activity, but it potentiated in concentration-dependent manner the spermine NONO-induced activation of this enzyme. Adrenochrome, like YC-1, sensitized guanylyl cyclase towards nitric oxide (NO) and produced the leftward shift of spermine NONO concentration responce curve. Addition of adrenochrome decreased the YC-1-induced leftward shift of spermine NONO concentration response curve. Adrenochrome also inhibited (by 63%) the enzyme activation by YC-1. These data demonstrates the possible competition between adrenochrome and YC-1. Thus, synergistic activation of NO-stimulated guanylyl cyclase activity by adrenochrome represents a new biochemical effect of this compound and indicates that adrenochrome may act as an endogenous regulator of NO-dependent stimulation of soluble guanylyl cyclase. This new property of adrenochrome, similar to YC-1, is necessary taking into account, especially under conditions of overproduction of adrenochrome in organism.

[Nitric oxide. Potentiation of NO-dependent activation of soluble guanylate cyclase--(patho)physiological and pharmacotherapeutical significance].

The paper reviews the molecular mechanism underlying the physiological effects of nitric oxide (NO), the role of the signalling system: NO-soluble guanylate cyclase-cyclic 3',5'-guanosine monophosphate (cGMP) in the realization of NO action. The data concerning the basic chemical characteristics of guanylate cyclase, such as the subunits structure, isoforms, modem concepts of the catalytic and regulatory centers of the enzyme are presented. The role of guanylate cyclase heme and the enzyme itself in the realization of physiological effects of NO is demonstrated. The data concerning a new NO-independent, allosteric activator of soluble guanylate cyclase, YC-1 (benzyl indasol derivative) synergistically increased the NO-dependent activation of soluble guanylate cyclase are presented. The data on guanylate cyclase sites responsible for binding of the enzyme with YC-1 and possible molecular mechanism underlying the synergistic increase of NO-dependent activation of soluble guanylate cyclase by YC-1 are presented. New compounds of endogenous nature capable to potentiate and synergistically increase the activation of guanylate cyclase by NO-donors have been revealed and investigated. The important physiological, pharmacotherapeutical and pathophysiological significance of this new fact is discussed.

[Potentiation of NO-dependent activation of soluble guanylate cyclase by polyamines].

The influence of polyamines (putrescine, spermidine, spermine) on the activity of human platelet soluble guanylate cyclase and stimulation of the enzyme by sodium nitroprusside, YC-1 and their combination was investigated. All polyamines used stimulated the guanylate cyclase activity and potentiated its activation by sodium nitroprusside. The stimulatory effects of sodium nitroprusside and putrescine (or spermine) were additive; spermidine produced a synergistic activation and increased the additive effect. All polyamines investigated inhibited the activation of the enzyme by YC-1 and decreased the synergistic activation of sodium nitroprusside-stimulated guanylate cyclase activity by YC-1 with approximately the same efficiency. The revealed ability of polyamines investigated to potentiate and synergistically increase (similar to YC-1, but less effective) NO-dependent activation of soluble guanylate cyclase represents a new biochemical effect of these compounds, which should be taken into consideration, especially due to the endogenous nature of polyamines. The data obtained suggest, that the specific functions of polyamines in the processes of cell growth and diffentiation may be also related to the ability of these compounds to activate soluble guanylate cyclase and increase cGMP level.

YC-1-like potentiation of NO-dependent activation of soluble guanylate cyclase by derivatives of protoporphyrin IX.

The influence of protoporphyrin IX derivatives--2,4-di(1-methoxyethyl)-deuteroporphyrin IX disodium salt (dimegin) and hematoporphyrin IX (HP)--on the activation of human platelet soluble guanylate cyclase by sodium nitroprusside was investigated. Dimegin and HP, like 1-benzyl-3-(hydroxymethyl-2-furyl)indazole (YC-1), produce synergistic effects on the activation of soluble guanylate cyclase by sodium nitroprusside. The synergistic activation of the enzyme by the combination of 10 microM sodium nitroprusside and 5 microM dimegin (or 5 microM HP) was 190 +/- 19 and 134 +/- 10%, respectively. The synergistic activation of guanylate cyclase by 3 microM YC-1 and 10 microM sodium nitroprusside was 255 +/- 19%. Dimegin and HP had no effect on the activation of guanylate cyclase by YC-1; they did not change the synergistic effect of YC-1 (3 microM) and sodium nitroprusside (10 microM) on guanylate cyclase activity. The synergistic activation of NO-stimulated guanylate cyclase activity by dimegin and HP represents a new biochemical effect of these compounds that may have important pharmacotherapeutic and physiological significance.

[No: a new look on the mechanism of action of old drugs].

The paper reviews the main approaches used for development of effective therapeutic means directly regulating signaling system "nitric oxide (NO)--soluble guanylate cyclase--cyclic guanosine monophosphate (cGMP)". Special attention is paid to the role of this system in the mechanism of action of so called "old drugs". Using new approaches for investigating the antihypertensive and anti-aggregatory action of NO and the role of guanylate cyclase in these processes the priority and fundamental data concerning the elaboration of the molecular basis of directed search and creation of new, effective antihypertensive and antiaggregatory compounds have been obtained. Studies of direct activation of soluble guanylate cyclase by the original NO-donors new activators of this enzyme resulted in discovery of new drugs participating in regulation of haemostasis and vascular tone. The priority data on new inhibitors of NO-dependent activation of guanylate cyclase (among which turn to the drugs) and the possible molecular mechanism of their pharmacological action are presented. It was shown at first time that the signaling system "NO-soluble guanylate cyclase-cGMP" may be involved in the mechanism of the therapeutic action of a number of widely used drugs including those acting as chemotherapeutics and antiprotozoics.

Nonselective inhibition of monoamine oxidases A and B by activators of soluble guanylate cyclase.

Several activators of soluble guanylate cyclase were investigated as potential inhibitors of rat liver mitochondrial monoamine oxidases (MAO) A and B. They all fitted into the previously designed "molds" of substrate-inhibitor binding sites of these enzymes. However, only two of them, NO donors (7-nitro-benzotetrazine-1,3-dioxide (7-NBTDO) and benzodifuroxan), caused nonselective inhibition of MAO A and MAO B with IC(50) values of 1.3-1.6 and 6.8-6.3 microM, respectively. The inhibitory effect on both MAO A and MAO B was reduced by mitochondria wash suggesting reversible mode of the enzyme inhibition. There was no correlation between potency of MAO inhibition and activation of human platelet soluble guanylate cyclase. The NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (carboxy-PTIO) had no effect on the manifestation of MAO inhibition by benzodifuroxan and 7-NBTDO; however, at 50 microM concentration carboxy-PTIO caused potent inhibition of MAO A with minor effect on MAO B activity. The data suggest that nonselective inhibition of MAO A and MAO B by benzodifuroxan and 7-NBTDO can be attributed to the properties of the chemical structures of these compounds. The results of the present study demonstrate a real possibility for the development of a new generation of effective reversible nonselective MAO inhibitors exhibiting equal inhibitory activity with respect to both MAO A and MAO B.

[Nitric oxide. The role of guanylate cyclase in its physiological effects]. / Oksid azota. Rol' rastvorimoi guanilattsiklazy v mekhanizmakh ego fiziologicheskikh éffektov.

In this review the molecular mechanism underlying the antihypertensive and anti-aggregatory actions of nitric oxide (NO) are discussed. It has been shown that these effects are directly connected with the activation of soluble guanylate cyclase and the accumulation of cyclic 3',5'-guanosine monophosphate (cGMP). The data concerning the basic chemical characteristics of guanylate cyclase, such as the subunits structure, isoforms, modern concepts on the catalytic and regulatory centers of the enzyme are presented. The role of heme and sulfhydryl groups in the functioning of guanylate cyclase and the significance of the nitrosyl-heme complex formed as a result of interaction of guanylate cyclase heme with NO are analyzed. Using new approaches for studying the antihypertensive and antiaggregatory actions of nitric oxide in combination with the newly obtained data on the regulatory role of guanylate cyclase in the platelet aggregation process, the most important results were obtained. The priority data on the new inhibitors of nitric oxide-dependent guanylate cyclase activation (among which turn to be the drugs) and the possible molecular mechanism of their pharmacological action are presented.

Derivatives of benzotetrazine-1,3-dioxide are new NO-donors, activators of soluble guanylate cyclase, and inhibitors of platelet aggregation.

The ability of 5-nitro-, 7-nitro-, and 5,7-dinitrobenzotetrazine-1,3-dioxides to generate nitric oxide (NO) and activate soluble guanylate cyclase was investigated. All of these compounds were found to be thiol-dependent NO-donors and guanylate cyclase activators. The maximal stimulatory effect of 5-nitro-, 7-nitro-, and 5,7-dinitrobenzotetrazine-1,3-dioxides was observed at 10 microM concentration and the activity increase was 4.5-, 15.0-, and 8.2-fold in the presence of 20 microM dithiothreitol and 11.3-, 31.6-, and 20.5-fold, respectively, in the presence of added glutathione (100 microM). The NO-dependent mechanism of benzotetrazine-1,3-dioxide nitroderivative-induced activation of soluble guanylate cyclase (in the presence of 100 microM glutathione) was confirmed by the inhibition (by 78%) of 7-nitrobenzotetrazine-1,3-dioxide (10 microM)-stimulated guanylate cyclase activity in the presence of the NO-scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (Carboxy-PTIO, 50 microM) and by the inhibition with 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ, 0.3 microM) of 5-nitro-, 7-nitro-, and 5,7-dinitrobenzotetrazine-1,3-dioxides (10 microM)-stimulated guanylate cyclase by 34, 69, and 39%, respectively. All compounds used inhibited ADP-induced aggregation of human platelets with IC50 of 10.0, 1.3, and 2.0 microM for 5-nitro-, 7-nitro-, and 5,7-dinitrobenzotetrazine-1,3-dioxides, respectively. A clearly defined correlation was established between the ability of the compounds to generate NO, activate soluble guanylate cyclase, and inhibit platelet aggregation.

[Endothelial dysfunction in the development of vascular complications in diabetes mellitus]. / Disfunktsiia épiteliia v razvitii sosudistykh oslozhnenii sakharnogo diabeta (problemnaia stat'ia).

Patients with type 1 diabetes, aged 18 to 42 years, were compared to those aged 11 to 22 years. Activities of endothelial vasoactive factors and endothelial and leukocyte adhesion molecules were studied at different stages of development diabetes complications: nephropathy and retinopathy. The findings reveal role of the vasoactive factors in microangiopathy course.

Ambroxol as an inhibitor of nitric oxide-dependent activation of soluble guanylate cyclase.

The influence of ambroxol on the activity of human platelet soluble guanylate cyclase and rat lung soluble guanylate cyclase was investigated. Ambroxol in the concentration range from 0.1 to 10 microM had no effect on the basal activity of both enzymes and slightly enhanced it at 50 and 100 microM. Ambroxol inhibited in a concentration-dependent manner the sodium nitroprusside-induced activation of both enzymes. The IC(50) values for inhibition by ambroxol of sodium nitroprusside-stimulated human platelet soluble guanylate cyclase and rat lung soluble guanylate cyclase were 3.9 and 2.1 microM, respectively. Ambroxol did not influence the stimulation of soluble guanylate cyclase by protoporphyrin 1X. Thus, it is possible that the molecular mechanism of the therapeutic action of ambroxol involves the inhibition of nitric oxide (NO)-dependent activation of soluble guanylate cyclase.

Carnosine as a regulator of soluble guanylate cyclase.

The molecular mechanism of the participation of carnosine in the functioning of soluble guanylate cyclase is discussed. It is shown that carnosine inhibits the activation of soluble guanylate cyclase by sodium nitroprusside and a derivative of furoxan--1,2,5-oxadiazolo-trioxide (an NO donor). However, carnosine has no effect on stimulation of the enzyme by a structural analog of the latter compound, a furazan derivative (1,2,5-oxadiazolo-dioxide) that is not an NO donor; nor was carnosine involved in the enzyme activation by protoporphyrin IX, whose stimulatory effect is not associated with the guanylate cyclase heme. The inhibition by carnosine of guanylate cyclase activation by an NO donor is due to the interaction of carnosine with heme iron with subsequent formation of a chelate complex. It was first demonstrated that carnosine is a selective inhibitor of NO-dependent activation of guanylate cyclase and may be used for suppression of activity of the intracellular signaling system NO-soluble guanylate cyclase-cGMP, whose sharp increase is observed in malignant tumors, sepsis, septic shock, asthma, and migraine.

[The activation of soluble guanylate cyclase by new NO donors as the basis of a directed search for new efficacious vasodilators and antiaggregants]. / Aktivatsiia rastvorimoi guanilattsiklazy novymi donorami NO kak osnova napravlennogo poiska novykh éffektivnykh vazodilatorov i antiagregantov.

The paper deals with the molecular mechanisms of antihypertensive and antiaggregatory actions of nitric oxide (NO). These effects of NO are shown to be directly associated with the activation of soluble guanylate cyclase and with the accumulation of 3',5'-guanosine monophosphate. The paper discusses the mechanism of activation of guanylate cyclase with new donors: the role and value of a nitrosyl-hemic complex formed in the interaction of guanylate cyclase with NO. New approaches to studying the mechanism of antihypertensive and antiaggregatory actions of the NO donors in question provided fundamental and priority data that lead to the development of the molecular bases of goal-oriented search and the synthesis of new effective vasodilators and antiaggregants. Examining the molecular mechanisms of targeted activation of soluble guanylate cyclase with new NO donors has revealed new enzyme activators that generate NO in the body and participate in the regulation of homeostasis and vascular tone.

Benzodifuroxan as an NO-dependent activator of soluble guanylate cyclase and a novel highly effective inhibitor of platelet aggregation.

The ability of benzodifuroxan (BDF) to activate human platelet guanylate cyclase was investigated. The maximal stimulatory effect (1160 +/- 86%) was observed at 0.01 mM concentration. Sodium nitroprusside produced the same stimulatory effect (1220 +/- 100%) but at a higher concentration (0.1 mM). 1-H-[1,2,4,]-Oxadiazolo[4, 3-alpha]quinoxalin-1-one (ODQ), an inhibitor of NO-dependent guanylate cyclase activation, attenuated the stimulatory effect of BDF (0.01 mM) by 75% and that of sodium nitroprusside (0.1 mM) by 80%. Increasing dithiothreitol concentration in the sample from 2. 10-6 to 2.10-4 M increased the stimulatory effect of BDF 2.7-fold. The possible involvement of sulfhydryl groups of low-molecular-weight thiols and guanylate cyclase in thiol-dependent activation of the enzyme is discussed. We have also found that BDF is a highly effective inhibitor of ADP-induced human platelet aggregation with IC50 of 6.10-8 M. The effect of sodium nitroprusside was much weaker (IC50, 5.10-5 M).