Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:4.6.1.2 (guanylate cyclase)
 8,497 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Nicorandil, pinacidil and lemakalim relaxed precontracted rings of canine cerebral artery. 2. The order of potency was lemakalim greater than nicorandil approximately equal to pinacidil, but all these agents were less effective than nimodipine. 3. The effects of nicorandil were inhibited by methylene blue but not by glibenclamide, while the effects of pinacidil and lemakalim were inhibited by glibenclamide but not by methylene blue. 4. Thus nicorandil probably causes relaxation mostly by effects on guanylate cyclase while lemakalim and pinacidil produce the same effect by action at ATP-dependent potassium channels.
Gen Pharmacol 1992 Mar
PMID:Vasodilatation of canine cerebral arteries by nicorandil, pinacidil and lemakalim. 135 69

Previously we showed that atrial natriuretic factor (ANF) decreases cardiac cell volume by inhibiting ion uptake by Na+/K+/2Cl- cotransport. Digital video microscopy was used to study the role of guanosine 3',5'-monophosphate (cGMP) in this process in rabbit ventricular myocytes. Each cell served as its own control, and relative cell volumes (volume(test)/volume(control)) were determined. Exposure to 10 microM 8-bromo-cGMP (8-Br-cGMP) reversibly decreased cell volume to 0.892 +/- 0.007; the ED50 was 0.77 +/- 0.33 microM. Activating guanylate cyclase with 100 microM sodium nitroprusside also decreased cell volume to 0.889 +/- 0.009. In contrast, 8-bromo-adenosine 3',5'-monophosphate (8-Br-AMP; 0.01-100 microM) neither altered cell volume directly nor modified the response to 8-Br-cGMP. The idea that cGMP decreases cell volume by inhibiting Na+/K+/2Cl- cotransport was tested by blocking the cotransporter with 10 microM bumetanide (BUM) and removing the transported ions. After BUM treatment, 10 microM 8-Br-cGMP failed to decrease cell volume. Replacement of Na+ with N-methyl-D-glucamine or Cl- with methanesulfonate also prevented 8-Br-cGMP from shrinking cells. The data suggest that 8-Br-cGMP, like ANF, decreases ventricular cell volume by inhibiting Na+/K+/2Cl-cotransport. Evidence that ANF modulates cell volume via cGMP was also obtained. Pretreatment with 10 microM 8-Br-cGMP prevented the effect of 1 microM ANF on cell volume, and ANF suppressed 8-Br-cGMP-induced cell shrinkage. Inhibiting guanylate cyclase with the quinolinedione LY83583 (10 microM) diminished ANF-induced cell shrinkage, and inhibiting cGMP-specific phosphodiesterase with M&B22948 (Zaprinast; 100 microM) amplified the volume decrease caused by a low dose of ANF (0.01 microM) approximately fivefold. In contrast, neither 100 microM 8-Br-cAMP nor 50 microM forskolin affected the response to ANF. The effects of ANF, LY83583, and M&B29948 on cGMP levels in isolated ventricular myocytes were confirmed by 125I-cGMP radioimmunoassay. These data argue that ANF shrinks cardiac cells by increasing intracellular cGMP, thereby inhibiting Na+/K+/2Cl- cotransport. Basal cGMP levels also appear to modulate cell volume.
J Gen Physiol 1992 Jul
PMID:Modulation of rabbit ventricular cell volume and Na+/K+/2Cl- cotransport by cGMP and atrial natriuretic factor. 135 6

1. Perfusion of the kidney with methylene blue, a soluble guanylate cyclase inhibitor, significantly enhanced the vasoconstrictor effects of angiotensin II, noradrenaline and phenylephrine but significantly reduced the vasodilator effect of acetylcholine without altering that of iloprost. 2. In the kidneys, which were perfused with Triton X-100 to remove endothelium, acetylcholine-induced vasodilation was completely abolished and angiotensin II-, noradrenaline- and phenylephrine-induced vasoconstriction was greatly reduced. 3. The vasodilator effect of iloprost was unchanged after perfusion of kidney with Triton X-100. 4. Neither methylene blue nor Triton X-100 significantly altered urine volume form normal and angiotensin II induced increase of urine volume. 5. These results were taken as evidence for the involvement of renal vascular endothelium originated EDRF in the responses of various vasoactive agents in the rabbit isolated perfused kidney.
Gen Pharmacol 1990
PMID:Possible involvement of endothelium in the responses of various vasoactive agents in rabbit isolated perfused kidney. 169 98

1. Atrial natriuretic factor (ANF) relaxes vascular smooth muscle through activation of particulate guanylate cyclase and generation of cyclic GMP. 2. From other laboratories, there is some evidence from cultured vascular smooth muscle cell studies for homologous desensitization of ANF-induced cGMP production and down-regulation of ANF receptors. 3. This series of studies demonstrates that homologous desensitization of ANF-induced relaxation of rat aortic ring preparations also occurs. 4. Heterologous desensitization could not be demonstrated to the vasoactive peptides angiotensin II or vasopressin, nor to nitroglycerin which has previously been shown to exhibit heterologous desensitization with other nitrovasodilators and shares some common elements in the pathway to vascular smooth muscle relaxation with ANF.
Gen Pharmacol 1990
PMID:Studies of the desensitization of atrial natriuretic factor and nitroglycerin in rat aortic rings. 217 11

Cyclic GMP is the second messenger in phototransduction and regulates the photoreceptor current. In the present work, we tried to understand the regulation mechanism of cytoplasmic cGMP levels in frog photoreceptors by measuring the photoreceptor current using a truncated rod outer segment (tROS) preparation. Since exogenously applied substance diffuses into tROS from the truncated end, we could examine the biochemical reactions relating to the cGMP metabolism by manipulating the cytoplasmic chemical condition. In tROS, exogenously applied GTP produced a dark current whose amplitude was half-maximal at approximately 0.4 mM GTP. The conductance for this current was suppressed by light in a fashion similar to when it is activated by cGMP. In addition, no current was produced in the absence of Mg2+, which is known to be necessary for the guanylate cyclase activity. These results indicate that guanylate cyclase was present in tROS and synthesized cGMP from exogenously applied GTP. The enzyme activity was distributed throughout the rod outer segment. The amount of synthesized cGMP increased as the cytoplasmic Ca2+ concentration of tROS decreased, which indicated the activation of guanylate cyclase at low Ca2+ concentrations. Half-maximal effect of Ca2+ was observed at approximately 100 nM. tROS contained the proteins involved in the phototransduction mechanism and therefore, we could examine the regulation of the light response waveform by Ca2+. At low Ca2+ concentrations, the time course of the light response was speeded up probably because cGMP recovery was facilitated by activation of the cyclase. Then, if the cytoplasmic Ca2+ concentration of a photoreceptor decreases during light stimulation, the Ca2+ decrease may explain the acceleration of the light response during light adaptation. In tROS, however, we did observe an acceleration during repetitive light flashes when the cytoplasmic Ca2+ concentration increased during the stimulation. This result suggests the presence of an additional light-dependent mechanism that is responsible for the acceleration of the light response during light adaptation.
J Gen Physiol 1989 Oct
PMID:Regulation of cGMP levels by guanylate cyclase in truncated frog rod outer segments. 257 52

We used an apparatus in which pieces of dark-adapted amphibian retinas (Rana pipiens, Bufo marinus) obtained under infrared illumination were exposed to precise intervals of 500-nm illuminations, and then frozen by contact of their outer segment surface with a liquid helium-cooled copper mirror. Sections of the frozen outer segment layer were obtained in a cryostat and then assayed for total extractable cyclic 3',5'-guanosine monophosphate (cGMP). Significant losses of cGMP with respect to the dark level were evident as early as 60 ms after light onset. With dim subsecond illuminations these losses were surprisingly large, which suggests a previously underestimated magnification in the cGMP cascade, or a transient substantial inhibition of guanylate cyclase activity in combination with increased cyclic GMP phosphodiesterase activity. Within the subsecond period, significant losses that were proportional to light intensity (2-log-unit range) and duration (60-550 ms) were generally not evident. However, losses significantly proportional to these factors became evident with durations of 1 s or longer. When pieces of retina were first illuminated (10 or 60 ms), then held in darkness for increasing periods before freezing, we observed a continuous loss of cGMP during the early postillumination dark period, followed by a recovery of the total cGMP level. The times for recovery to the preillumination level appear to be significantly longer than times reported for the recovery of the photoreceptor membrane potential after similar light exposures.
J Gen Physiol 1988 Dec
PMID:Light-induced losses and dark recovery rates of guanosine 3',5'-cyclic monophosphate in rod outer segments of intact amphibian photoreceptors. 285 Oct 28

1. Ethacrynic acid, an agent that alkylates sulfhydryl residues, inhibited sodium nitroprusside- and 8-bromo cyclic GMP-induced relaxations. 2. Sodium nitroprusside-induced increased levels of cyclic GMP were unaltered by ethacrynic acid. 3. Concentrations of ethacrynic acid that inhibited sodium nitroprusside-induced relaxation did not affect sodium nitroprusside-activation of crude soluble and particulate fractions of guanylate cyclase, while a higher concentration of ethacrynic acid did inhibit the activation. 4. Cystamine, an agent that oxidizes sulfhydryl residues, inhibited sodium nitroprusside-activation of crude soluble and particulate fractions of guanylate cyclase. Exposure of intact rat aorta to cystamine inhibited basal guanylate cyclase activity in the particulate fraction but, in general, not in the soluble fraction. 5. These results are consistent with the hypothesis that vascular smooth muscle relaxation requires sulfhydryl groups. The sulfhydryl groups that presumably are alkylated by ethacrynic acid are not contained within guanylate cyclase and are involved at a regulatory step after the formation of cyclic GMP. The sulfhydryl groups altered by cystamine may be located on particulate guanylate cyclase and a role for particulate guanylate cyclase in nitrovasodilator-induced relaxation needs to be examined further.
Gen Pharmacol 1988
PMID:Effects of ethacrynic acid and cystamine on sodium nitroprusside-induced relaxation, cyclic GMP levels and guanylate cyclase activity in rat aorta. 289 33

The rat aorta responds biphasically to norepinephrine (NE) in calcium-free medium. The dissociable phasic and tonic components of the contraction are mediated through alpha-adrenoreceptor activation and mobilization of intracellular calcium. Dibutyryl-cAMP, papaverine (which inhibits cAMP phosphodiesterase and increases cAMP levels), bromo-cGMP, and sodium nitroprusside (which stimulates guanylate cyclase and increases cGMP levels) inhibited in a concentration-dependent manner the biphasic aortic contractions induced by NE in calcium-free medium. The log IC50 values of each of these smooth muscle relaxants for inhibition of the biphasic response to NE in calcium-free medium were very close to those required for inhibition of the contractions induced by NE or KCl in presence of extracellular calcium. The present findings indicate that the phasic and tonic components of NE-induced aortic contractions in calcium-free medium are subject to similar intracellular regulatory mechanisms by cyclic nucleotides at a step subsequent to alpha-adrenoreceptor occupancy by NE, since dibutyryl-cAMP and bromo-cGMP inhibited the tonic component of NE-induced contraction noncompetitively.
Gen Pharmacol 1983
PMID:Norepinephrine-induced contractions of the rat aorta in the absence of extracellular calcium--III. Effects of cyclic nucleotides. 631 28

The biochemical signaling pathways involved in nitric oxide (NO)-mediated cholinergic inhibition of L-type Ca2+ current (ICa[L]) were investigated in isolated primary pacemaker cells from the rabbit sinoatrial node (SAN) using the nystatin-perforated whole-cell voltage clamp technique. Carbamylcholine (CCh; 1 microM), a stable analogue of acetylcholine, significantly inhibited ICa(L) after it had been augmented by isoproterenol (ISO; 1 microM). CCh also activated an outward K+ current, IK(ACh). Both of these effects of CCh were blocked completely by atropine. Preincubation of the SAN cells with L-nitro-arginine methyl ester (L-NAME; 0.2-1 mM), which inhibits NO synthase (NOS), abolished the CCh-induced attenuation of ICa(L) but had no effect on IK(ACh). Coincubation of cells with both L-NAME and the endogenous substrate of NOS, L-arginine (1 nM), restored the CCh-induced attenuation of ICa(L), indicating that L-NAME did not directly interfere with the muscarinic action of CCh on ICa(L). In the presence of ISO the CCh-induced inhibition of ICa(L) could be mimicked by the NO donor 3-morpholino-sydnonimine (SIN-1; 0.1 mM). SIN-1 had no effect on its own or after a maximal effect of CCh had developed, indicating that it does not inhibit ICa(L) directly. SIN-1 failed to activate IK(ACh), demonstrating that it did not activate muscarinic receptors. Both CCh and NO are known to activate guanylyl cyclase and elevate intracellular cGMP. External application of methylene blue (10 microM), which interferes with the ability of NO to activate guanylyl cyclase, blocked the CCh-induced attenuation of ICa(L). However, it also blocked the activation of IK(ACh), suggesting an additional effect on muscarinic receptors or G proteins. To address this, a separate series of experiments was performed using conventional whole-cell recordings with methylene blue in the pipette. Under these conditions, the CCh-induced attenuation of ICa(L) was blocked, but the activation of IK(ACh) was still observed. Methylene blue also blocked the SIN-1-induced decrease in ICa(L). 6-anilino-5,8-quinolinedione (LY83583; 30 microM), an agent known to decrease both basal and CCh-stimulated cGMP levels, prevented the inhibitory effects of both CCh and SIN-1 on ICa(L), but had no effect on the activation of IK(ACh) by CCh. In combination, these results show that CCh- and NO-induced inhibition of ICa(L) is mediated by cGMP.(ABSTRACT TRUNCATED AT 400 WORDS)
J Gen Physiol 1995 Jul
PMID:A cellular mechanism for nitric oxide-mediated cholinergic control of mammalian heart rate. 749 38

1. Isolated human platelets were used to investigate the effect of atrial natriuretic peptide (ANP) on in vitro platelet aggregation induced by epinephrine, ADP, collagen and 5-hydroxytryptamine. As a direct stimulant of particulate guanylate cyclase, ANP is known to have no direct effect on platelets which contain soluble guanylate cyclase. 2. In our experiments ANP inhibited epinephrine- and partially ADP-induced aggregation in vitro and this effect was suggested to be the result of an interaction of the peptide with adenylate cyclase in platelets. However, the concentrations required to produce this effect were higher than those expected to be found in the circulation both physiologically and pathologically. 3. We therefore conclude that though the peptide may inhibit-aggregation via adenylate cyclase activation, it is unlikely that ANP may play a direct role in preventing platelets aggregating.
Gen Pharmacol 1995 Oct
PMID:Platelet aggregation and atrial natriuretic peptide. 759 Jan 39


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