Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

The effects of nitrates on a Ca+2 increase and the content of cyclic nucleotides in human platelets were studied. Nitroglycerin (GTN), isosorbide dinitrate (ISDN) and sodium nitroprusside (NP) were found to inhibit dose-dependently the intracellular Ca+2 increase induced by the platelet activating factor (PAF). The inhibiting effect of NP was at lower concentrations than those of GTN and ISDN. GTN calcium blocking action did not change significantly regardless of vasopressin, serotonin or PAF used as inducers of the intracellular Ca+2 increase. GTN suppressed the PAF provoked Mn+2 entering into the cells. NP and GTN induced increase of the cGMP content correlated with their calcium blocking activity. They did not augment the level of cAMP. Methylene blue (MB), a guanylate cyclase and glutathione reductase inhibitor, decreased the calcium blocking effect of GTN and its influence on the cGMP content but failed to suppress the inhibitory effect of NP. Ascorbic acid increased the calcium blocking effect of NP but did not influence the inhibitory effect of GTN. An increase in Ca+2 content induced by PAF in platelets from patients with chronic congestive heart failure was significantly higher in the group with dilatation cardiomyopathy. The effect of 10 mg of ISDN sublingually on forearm venous tone was higher in patients with initially elevated venous tone. There was a direct statistical correlation between the IC50 of GTN calcium blocking effects in platelets and the elevation of a forearm venous tone reaction from a statistic mean reaction to ISDN.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[New approaches to the study of the mechanism of action of nitrates]. 285 8

Apart from the generally known functions, the heart has also an endocrine function. Atrial cardiocytes, being typical secretory cells, release peptide hormones into the blood stream: atrial natriuretic peptide containing 28 amino acids and cardiodilatin. The structure of atrial peptides was determined. It was shown that both peptides were derived from their common precursor, a protein containing 151 amino acids. The presence of specific receptors is demonstrated on plasmatic membranes of cells of kidney epithelium, arterial smooth muscle, arterial endothelium, kidney cortex and hypophysis. The interaction of atrial peptides with these receptors activates the guanylate cyclase system. The biological action of atrial peptides manifests itself in the quick, massive and instantaneous increase of diuresis and electrolyte excretion, elevated clearance of creatinine, decrease of kidney vascular resistance, intensification of glomerular filtration, inhibition of stimulated secretion of aldosterone, relaxation of blood vessels, elimination of arterial and intestinal spasm induced by various endogenous and exogenous vasoconstrictors and in correction of kidney hypertension. Various radioimmunoassays for the presence of atrial peptides in human plasma were developed; it was shown that in patients with congestive heart failure the content of atrial peptides is increased.
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PMID:[Endocrine function of the heart. Structure and biological properties of peptides secreted by the heart atrium]. 295 15

Plasma concentrations of cardiodilatin, the peptide sequence at the amino terminal of the pro-atrial natriuretic peptide, in 17 normal subjects ranged from 59 to 202 (mean 118 (SEM) (9] pmol/l. Recumbency increased the mean (SEM) concentration to 160 (13) pmol/l. The plasma concentration of cardiodilatin in 24 patients with congestive cardiac failure was much higher (964 (175) pmol/l) than in the normal subjects. It was highest in those with heart failure in New York Heart Association functional classes III and IV and the concentration correlated both with atrial natriuretic peptide concentrations and left ventricular ejection fraction. Concentrations rose during induced tachycardia in three patients tested. Chromatography showed a single clean peak of plasma cardiodilatin immunoreactivity. It seems that cardiodilatin is a second circulating cardiac peptide that is jointly released with atrial natriuretic peptide by common stimuli. Other workers have reported that, like atrial natriuretic peptide, three partial cardiodilatin sequences can stimulate renal particulate guanylate cyclase and increase cyclic guanosine monophosphate. The simultaneous release of cardiodilatin in higher circulating concentrations than atrial natriuretic peptide may be relevant to the finding that appropriate concentrations of exogenous atrial natiuretic peptide alone do not produce the full renal effects associated with endogenous peptide release.
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PMID:Increase in plasma concentrations of cardiodilatin (amino terminal pro-atrial natriuretic peptide) in cardiac failure and during recumbency. 297 Feb 69

The search for natriuretic hormones or factors by studies of negative pressure breathing, atrial distension experiments, head-out water immersion, expansion of blood volume, Na+/K+-ATPase inhibitors and parabiosis experiments in Dahl rats has led to the finding that the atria are a peptide-secreting endocrine gland. This new natriuretic hormone has now been purified, sequenced and synthetized, and its cDNA and gene have been cloned. The native and synthetic hormones exert identical wide ranging effects (possibly through particulate guanylate cyclase stimulation and adenylate cyclase inhibition) on the kidney, blood vessels, adrenal cortex, and pituitary. Physiopathologic implications of the hormone in experimental hypertension, congestive heart failure, and expansion of blood volume are beginning to emerge.
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PMID:The heart and the atrial natriuretic factor. 298 29

Extracts of mammalian atria, but not ventricles, induce marked diuresis, natriuresis, and reduction in blood pressure when infused systemically in rats and dogs. These extracts also inhibit aldosterone biosynthesis and renal renin release. Natriuretic peptides, 21 amino acids and longer, have been isolated from atria of rodents and man, and share a nearly homologous amino acid sequence at the carboxyterminus. Natriuretic activity resides in a 17-amino acid ring formed by a disulfide bridge, and the C-terminal Phe-Arg appears necessary for full biological potency. The deoxyribonucleic acid-encoding atrial natriuretic peptides have been cloned and the gene structure elucidated. Reduction of the diuretic and natriuretic responses to an acute volume load by right atrial appendectomy first suggested a role for atrial peptides in the physiological response to plasma volume expansion. Subsequently, release of peptides with natriuretic and spasmolytic properties from isolated heart preparations in response to right atrial distension was demonstrated by bioassay and radioimmunoassay. The presence of these peptides in normal rat and human plasma in concentrations of 20-100 pM, and the findings of increased levels in response to acute and chronic plasma volume expansion, rapid atrial tachyarrhythmias, systemic hypertension, congestive heart failure, and renal insufficiency imply that they play an important role in body fluid homeostasis. The mechanisms by which atrial peptides increase renal salt and water excretion are as yet unclear. Renal vascular effects have been consistently demonstrated, and limited evidence for direct actions on tubule ion transport has also been reported recently. In vitro, these peptides cause precontracted vascular and nonvascular smooth muscle to relax, mediated by a direct action on smooth muscle cells. Specific receptors for these peptides have been characterized in crude membranes prepared from whole kidney homogenates and adrenal glomerulosa cells, in intact glomeruli and cultured glomerular mesangial cells, and in intact bovine aortic smooth muscle and endothelial cells. Natriuretic peptides stimulate cyclic guanosine monophosphate accumulation in target tissues, and augment particulate guanylate cyclase activity in membrane fractions, suggesting that cyclic guanosine monophosphate is the second messenger mediating their cellular action.
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PMID:George E. Brown memorial lecture. Role of atrial peptides in body fluid homeostasis. 301 7

Two independent series of biomedical investigations have led to the discovery that the atria are a peptide-secreting endocrine gland. The first is mainly morphological and starts with the finding that mammalian atrial but not ventricular cardiocytes contain "dense bodies". These "dense bodies" later called "specific granules" were found to be different from lysosomes, to be made up of proteins and to incorporate both 3H-leucine and 3-H-fucose in a pattern typical of peptide-secreting endocrine cells. The finding that rat atrial granulation varied with the sodium and water balance led to the crucial observation that atrial extracts have natriuretic and diuretic effects. In less than 4 years, this new natriuretic hormone has been purified, sequenced and synthetized, and its cDNA and gene have been cloned. The ANF gene has been assigned to the distal short arm of chromosome 1 in band 1P36 while the mouse gene is localized in chromosome 4. The native and synthetic hormones exert identical wide ranging effects (possibly through particulate guanylate cyclase stimulation and adenylate cyclase inhibition) on the kidney, blood vessels, adrenal cortex and pituitary. Physiopathologic implications of the hormone in experimental hypertension, congestive heart failure and expansion of blood volume are already beginning to emerge. On the other hand, the search for natriuretic hormones or factors by studies of negative pressure breathing, atrial distention experiments, head-out water immersion, expansion of blood volume, Na+/K-ATPase inhibition and parabiosis experiments in Dahl rats has provided a general framework within which to interpret this new cardiac function.
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PMID:[The heart, an endocrine gland]. 301 75

Two independent series of biomedical investigations have led to the discovery that the atria constitute a peptide-secreting endocrine gland. The first investigation is mainly morphological and started with the finding that mammalian atrial (but not ventricular) cardiocytes contain "dense bodies." These "dense bodies," later called "specific granules," were found to be different from lysosomes; to be made up of proteins; and to incorporate both 3H-leucine and 3H-fucose in a pattern typical of peptide-secreting endocrine cells. The finding that rat atrial granulation varied with the sodium and water balance led to the crucial observation that atrial extracts have natriuretic and diuretic effects. In less than five years, this new natriuretic hormone has been purified, sequenced and synthesized, and its CDNA and gene have been cloned. The atrial natriuretic factor (ANF) gene has been assigned to the distal short arm of chromosome 1 in band 1P36, while the mouse gene is localized in chromosome 4. The native and synthetic hormones exert identical wide ranging effects (possibly through particulate guanylate cyclase stimulation and adenylate cyclase inhibition) on the kidney, blood vessels, adrenal cortex, and pituitary. Physiopathologic implications of the hormone in experimental hypertension, congestive heart failure, and expansion of blood volume are already beginning to emerge. Concurrently, the search for the function of natriuretic hormones or factors (through studies of negative pressure breathing, atrial distension experiments, head-out water immersion, expansion of blood volume, Na+/K+-ATPase inhibition, and parabiosis experiments in Dahl rats) has provided a general framework within which to interpret this new cardiac function.
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PMID:The heart as an endocrine gland. 302 9

The nitrates used therapeutically in angina pectoris and congestive heart failure are, from a chemical point of view, organic nitroesters. Their principal pharmacological effect is vascular smooth muscle relaxation, leading to vasodilation, which explains their therapeutic effects. Several mechanisms have been proposed for their mode of action at the cellular level, in order to explain vascular smooth muscle relaxation. Today, there is strong evidence that organic nitroesters stimulate the enzyme guanylate cyclase in the smooth muscle cell. This enzyme produces a cyclic nucleotide, cyclic guanosine-3',5'-monophosphate (cGMP), which in turn eventually lowers the free calcium concentration in the cytosol to induce relaxation. The exact mechanism by which the organic nitroesters stimulate guanylate cyclase is still obscure. Preliminary results from our laboratory indicate that there may be more than one mechanism responsible for the activation of the enzyme. Knowledge of the mode of action at the cellular level is probably important in order to understand the mechanism(s) behind the development of tolerance towards the organic nitroesters.
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PMID:Nitrates. Mode of action at a cellular level. 304 Mar 73

Nitroglycerin has maintained its position in the treatment of angina pectoris for more than a century. Efficacy of oral nitrates has been established and compares well with that of other anti-anginal drugs. New delivery systems are being developed for sustained systemic nitrate action. Beneficial action of nitrates in congestive heart failure and their crucial role in unstable angina and acute myocardial infarction has further widened their therapeutic use. A plausible hypothesis of the mechanism of nitrate-induced vasodilation has been presented, involving production of nitrosothiols and activation of guanylate cyclase in the vascular smooth muscle. Recent developments suggest that the rate degradation of nitrates and formation of nitrosothiols in the vascular smooth muscle are linked, offering an explanation to the relatively rapidly developing, but partial vascular tolerance during high-dose nitrate therapy.
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PMID:Efficacy of different forms of nitrates in angina pectoris. 392 83

The combination of hydralazine and nitrates has been shown to provide long-term benefit in congestive heart failure, despite a nitrate dosage that should induce tolerance. To assess the interactions between hydralazine and nitroglycerin, aortic rings were isolated from male Wistar rats. In rings precontracted with phenylephrine, hydralazine incubation (10 microM and 0.1 mM) potentiated the responses to nitroglycerin (p < 0.05) but not to sin-1 (a direct activator of guanylate cyclase), 8-bromocyclic guanylate monophosphate, and forskolin (an adenylate cyclase activator). In similar conditions, the incubation of isoniazid (0.1 mM, used as a pyridoxal-sequestering agent without direct vasoactive properties) also potentiated the dose-response curve to nitroglycerin (p < 0.05). In aortas isolated from rats rendered nitrate tolerant in vivo (50 mg/kg subcutaneously twice daily during 4 days), hydralazine partially attenuated tolerance (p < 0.05). Our results suggest that the observed interaction between hydralazine and nitroglycerin may involve an inhibition of pyridoxal-dependent reactions, such as the catabolism of methionine and cysteine. This may enhance the availability of sulfhydryl-containing compounds, and therefore potentiate the responses to nitroglycerin.
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PMID:Interaction between hydralazine and nitrovasodilators in vascular smooth muscle. 768 11


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