cyclic-gmp and sodium-bisulfide

The study was designed to examine if the vasorelaxant effect of hydrogen sulfide was mediated by sulfhydration-associated phosphodiesterase (PDE) 5A dimerization. The thoracic aorta of rat was separated and the vasorelaxant effects were examined with in vitro vascular perfusion experiments. The dimerization and sulfhydration of PDE 5A and soluble guanylatecyclase (sGC) were measured. PDE 5A and protein kinase G (PKG) activities were tested. Intracellular cGMP content was detected by enzyme-linked immunosorbent assay (ELISA). The results showed that NaHS relaxed isolated rat vessel rings at an EC50 of (1.79 ± 0.31)×10-5mol/L, associated with significantly increased PKG activity and cGMP content in vascular tissues. Sulfhydration of sGC β1 was increased, while the levels of sGC αβ1 dimers were apparently decreased after incubation with NaHS in vascular tissues. Moreover, PDE 5A homodimers were markedly decreased, and accordingly the PDE 5A activity demonstrated by the content of 5'-GMP was significantly decreased after incubation with NaHS or GYY4137. Mechanistically, both NaHS and GYY4137 significantly enhanced the PDE 5A sulfhydration in vascular tissues. DTT partially abolished the effects of NaHS on PDE 5A activity, cGMP content and vasorelaxation. Therefore, the present study for the first time suggested that H2S exerted vasorelaxant effect probably via sulfhydration-associated PDE 5A dimerization.

Topics: Animals; Aorta; Cyclic GMP; Cyclic GMP-Dependent Protein Kinases; Cyclic Nucleotide Phosphodiesterases, Type 5; Enzyme Activation; Guanylate Cyclase; Hydrogen Sulfide; Male; Morpholines; Myocytes, Smooth Muscle; Organothiophosphorus Compounds; Protein Multimerization; Rats; Signal Transduction; Sulfides; Vasodilator Agents

We studied the role of cyclic nucleotides in the influence of hydrogen sulfide (H

Topics: Animals; Cyclic AMP; Cyclic GMP; Hydrogen Sulfide; Jejunum; Muscle Contraction; Nucleotides, Cyclic; Rats; Signal Transduction; Sulfides

H2S is known to confer cardioprotection; however, the pathways mediating its effects in vivo remain incompletely understood. The purpose of the present study is to evaluate the contribution of cGMP-regulated pathways in the infarct-limiting effect of H2S in vivo.. Anaesthetized rabbits were subjected to myocardial ischaemia (I)/reperfusion (R), and infarct size was determined in control or H2S-exposed groups. The H2S donor sodium hydrosulfide (NaHS, an agent that generates H2S) increased cardiac cGMP and reduced the infarct size. The cGMP-dependent protein kinase (PKG)-I inhibitor DT2 abrogated the protective effect of NaHS, whereas the control peptide TAT or l-nitroarginine methyl ester (l-NAME) did not alter the effect of NaHS. Moreover, the KATP channel inhibitor, glibenclamide, partially reversed the effects of NaHS, whereas inhibition of mitochondrial KATP did not modify the NaHS response. NaHS enhanced phosphorylation of phospholamban (PLN), in a PKG-dependent manner. To further investigate the role of PLN in H2S-mediated cardioprotection, wild-type and PLN KO mice underwent I/R. NaHS did not exert cardioprotection in PLN KO mice. Unlike what was observed in rabbits, genetic or pharmacological inhibition of eNOS abolished the infarct-limiting effect of NaHS in mice.. Our findings demonstrate (i) that administration of NaHS induces cardioprotection via a cGMP/PKG/PLN pathway and (ii) contribution of nitric oxide to the H2S response is species-specific.

Topics: Animals; Calcium-Binding Proteins; Cyclic GMP; Cyclic GMP-Dependent Protein Kinases; Disease Models, Animal; Enzyme Activation; Female; Hydrogen Sulfide; Male; Mice, Inbred C57BL; Mice, Knockout; Myocardial Infarction; Myocardial Reperfusion Injury; Myocytes, Cardiac; Nitric Oxide; Nitric Oxide Synthase Type III; Phosphorylation; Protein Kinase Inhibitors; Rabbits; Signal Transduction; Species Specificity; Sulfides

Hydrogen sulfide (H2S) is an endogenous gaseous molecule formed from L-cysteine in vascular tissue. In the present study, cardiovascular responses to the H2S donors Na2S and NaHS were investigated in the anesthetized rat. The intravenous injections of Na2S and NaHS 0.03-0.5 mg/kg produced dose-related decreases in systemic arterial pressure and heart rate, and at higher doses decreases in cardiac output, pulmonary arterial pressure, and systemic vascular resistance. H2S infusion studies show that decreases in systemic arterial pressure, heart rate, cardiac output, and systemic vascular resistance are well-maintained, and responses to Na2S are reversible. Decreases in heart rate were not blocked by atropine, suggesting that the bradycardia was independent of parasympathetic activation and was mediated by an effect on the sinus node. The decreases in systemic arterial pressure were not attenuated by hexamethonium, glybenclamide, N(w)-nitro-L-arginine methyl ester hydrochloride, sodium meclofenamate, ODQ, miconazole, 5-hydroxydecanoate, or tetraethylammonium, suggesting that ATP-sensitive potassium channels, nitric oxide, arachidonic acid metabolites, cyclic GMP, p450 epoxygenase metabolites, or large conductance calcium-activated potassium channels are not involved in mediating hypotensive responses to the H2S donors in the rat and that responses are not centrally mediated. The present data indicate that decreases in systemic arterial pressure in response to the H2S donors can be mediated by decreases in vascular resistance and cardiac output and that the donors have an effect on the sinus node independent of the parasympathetic system. The present data indicate that the mechanism of the peripherally mediated hypotensive response to the H2S donors is uncertain in the intact rat.

Topics: Animals; Arachidonic Acid; Blood Pressure; Cardiac Output; Cyclic GMP; Heart Rate; Hydrogen Sulfide; Male; Nitric Oxide; Potassium Channels; Rats; Rats, Sprague-Dawley; Sulfides; Vascular Resistance

Hydrogen sulphide (H(2)S) is an endogenously generated gaseous transmitter that has recently been suggested to regulate cardiovascular functions. To date, there is no direct evidence for a potential role of H(2)S in regulating calcium channels in the heart. The present study aims to examine the hypothesis that H(2)S is a novel inhibitor of the L-type calcium channel current (I(Ca,L)).. Electrophysiological measurements were performed in cardiomyocytes isolated from Wistar-Kyoto and spontaneously hypertensive rats. Bath application of 100 microM NaHS (a H(2)S donor) significantly reduced the time required for the repolarization of the action potential. Inhibition of the peak I(Ca,L) by NaHS was determined to be concentration-dependent (25, 50, 100, 200, and 400 microM). NaHS inhibited the recovery from depolarization-induced inactivation. Electric field-induced [Ca(2+)]i transients and contraction of single cardiomyocytes and isolated papillary muscles were reduced by NaHS treatment. In contrast, caffeine induced an increase in [Ca(2+)]i that was not altered by NaHS. NaHS had no effect on the K(ATP) current or on the levels of cAMP and cGMP in the current study.. H(2)S is a novel inhibitor of L-type calcium channels in cardiomyocytes. Moreover, H(2)S-induced inhibition of [Ca(2+)]i appears to be a secondary effect owing to its initial action towards I(Ca,L). The inhibitory effect of H(2)S on I(Ca,L) requires further investigation, particularly in the exploration of new pathways involved in cardiac calcium homeostasis and disease pathology.

Topics: Action Potentials; Animals; Calcium Channel Blockers; Calcium Channels, L-Type; Calcium Signaling; Cells, Cultured; Cyclic AMP; Cyclic GMP; Dose-Response Relationship, Drug; Electric Stimulation; Hydrogen Sulfide; KATP Channels; Male; Myocardial Contraction; Myocytes, Cardiac; Papillary Muscles; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Sulfides; Time Factors

Superoxide (O(2)(*-)), derived from nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, is associated with acute respiratory distress syndrome (ARDS). NADPH oxidase activity and expression are blocked by nitric oxide (NO) and sildenafil. As another gas, hydrogen sulphide (H(2)S) is formed by blood vessels, the effect of sodium hydrosulphide (NaHS) and the H(2)S-donating derivative of sildenafil, ACS6, on O(2)(*-) formation and the expression of gp91(phox) (a catalytic subunit of NADPH oxidase) in porcine pulmonary arterial endothelial cells (PAECs) was investigated.. PAECs were incubated with 10 ng mL(-1) tumour necrosis factor-alpha (TNFalpha) (+/-NaHS or ACS6), both of which released H(2)S, for 2 h or 16 h. O(2)(*-) was measured. Expression of gp91(phox) was measured by western blotting and the role of cyclic AMP (cAMP) and/or cyclic GMP was assessed using protein kinase inhibitors.. After either 2- or 16-h incubations, O(2)(*-) formation by PAECs was inhibited by NaHS or ACS6, with IC(50) values of about 10 nM and less than 1 nM, respectively. Both 100 nM NaHS and 1 nM ACS6 completely inhibited gp91(phox) expression induced by TNFalpha. The effects of NaHS were blocked by the inhibition of protein kinase A (PKA), but not PKG, and not by the inhibition of guanylyl cyclase. Effects of ACS6 were blocked by inhibition of both PKA and PKG. Both NaHS and ACS6 augmented cAMP formation.. H(2)S inhibited O(2)(*-) formation and upregulation of NADPH oxidase in PAECs through the adenylyl cyclase-PKA pathway. ACS6 may be effective in treating ARDS through both elevation of cAMP and inhibition of phosphodiesterase type 5 activity.

Topics: Adenylyl Cyclases; Animals; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Cyclic GMP; Cyclic GMP-Dependent Protein Kinases; Endothelial Cells; Gene Expression Regulation; Guanylate Cyclase; Hydrogen Sulfide; Inhibitory Concentration 50; Male; NADPH Oxidases; Phosphodiesterase 5 Inhibitors; Piperazines; Pulmonary Artery; Respiratory Distress Syndrome; Sulfides; Sulfones; Superoxides; Swine; Time Factors; Tumor Necrosis Factor-alpha

H(2)S is endogenously generated in vascular smooth muscle cells. The signal transduction pathways involved in the vascular effects of H(2)S have been unclear and were investigated in the present study. H(2)S induced a concentration-dependent relaxation of rat aortic tissues that was not affected by vascular denervation. The vasorelaxant potency of H(2)S was attenuated by the removal of the endothelium. Similarly, the blockade of nitric oxide synthase or the coapplication of the Ca(2+)-dependent K(+) channel blockers apamin and charybdotoxin reduced the H(2)S-induced relaxation of the endothelium-intact aortic tissues. Sodium nitroprusside (SNP)-induced relaxation was completely abolished by either 1H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one (ODQ) or NS- 2028, two soluble guanylate cyclase inhibitors. Instead of inhibition, ODQ and NS-2028 potentiated the H(2)S-induced vasorelaxation, which was suppressed by superoxide dismutase. The vasorelaxant effect of H(2)S was also significantly attenuated when Ca(2+)-free bath solution was used. Finally, pretreatment of aortic tissues with H(2)S reduced the relaxant response of vascular tissues to SNP. Our results demonstrate that the vascular effect of H(2)S is partially mediated by a functional endothelium and dependent on the extracellular calcium entry but independent of the activation of the cGMP pathway.

Topics: Animals; Aorta; Calcium; Cyclic GMP; Denervation; Drug Synergism; Endothelium, Vascular; Extracellular Space; Gases; Hydrogen Sulfide; In Vitro Techniques; Male; Nitric Oxide Donors; Nitroprusside; Osmolar Concentration; Rats; Rats, Sprague-Dawley; Sulfides; Vasodilation; Vasodilator Agents