Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0085580 (essential hypertension)
 14,686 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In order to evaluate the correlation between sulfur amino acids (derived mainly form animal protein in the diet) and blood pressure, free amino acids, including sulfur amino acids such as taurine and methionine, were determined in the plasma and cerebrospinal fluid (CSF) of twelve normotensive subjects and twelve patients with essential hypertension under nutritional control after at least 10 days of standard hospital diet (total calorie and protein content: 2100-2300 Cal per day and 78-83 g per day, respectively). The results obtained were as follows: plasma taurine, serine, methionine and threonine were significantly lower in patients with essential hypertension than in normotensive patients. The levels of plasma taurine, serine, methionine and total sulfur amino acids in individuals correlated inversely to systolic blood pressure. No difference was observed in the CSF levels of free amino acids in normotensive and hypertensive patients. As taurine, methionine and serine are involved in the metabolism of sulfur amino acids, these observations support the view that the decrease in plasma sulfur amino acids may be a factor contributing to elevated blood pressure.
 ...
PMID:Decrease of plasma sulfur amino acids in essential hypertension. 393 88

Several intervention studies with angiotensin I converting enzyme (ACE) inhibitors have demonstrated a remarkable improvement in the treatment of patients with primary hypertension and congestive heart failure. Since ACE inhibitor therapy in patients with congestive heart failure not only improves systemic haemodynamics but also provides a better prognosis, the cardiac renin-angiotensin system is apparently one of the major targets of ACE inhibitor therapy. Recent studies provided evidence that the human heart contains high affinity Ang II (Ang II) receptors with both subtype population and ACE. In addition to ACE, a novel cardiac Ang II forming enzyme (human chymase) has been identified in human hearts. Unlike in the rat heart, the minor (10%) component of Ang II-forming activity in the left ventricle is due to ACE, whereas the major (80%) component is due to human chymase. This novel cardiac serine proteinase has been purified from the human left ventricle and characterized, and recently, the cDNA and the gene for this enzyme have been cloned. Biochemical characterization revealed that human chymase is the most efficient and specific Ang II-forming enzyme described thus far, but the cellular and regional distribution of the two Ang II-forming enzymes seems to be different. ACE is mainly localized in endothelial cells and fibroblasts and the expression level is higher in atria than ventricles, whereas chymase is synthesized and stored in secretory granules of mast cells, endothelial cells, and mesenchymal cells, and after its secretion localized in the interstitial region of the myocardium and its expression is higher in ventricles than atria. These results imply distinct roles of these two Ang II-forming enzymes in cardiac Ang II formation and in the physiological function of the human heart. Since localization of cardiac renin and angiotensinogen were also identified in human heart, it is important to understand the detailed mechanisms of the tissue Ang II formation and its contribution to the pathophysiological changes in cardiovascular diseases.
 ...
PMID:Tissue angiotensin II system in the human heart. 771 17

Angiotensin-I converting enzyme (ACE) inhibitors have provided a remarkable improvement in the treatment of patients with primary hypertension and congestive heart failure. The cardiac renin-angiotensin system is one of the major targets of ACE inhibitor therapy since recent studies show that the human heart contains high affinity angiotensin II (Ang II) receptors and ACE activity. However, it is not clear why ACE inhibitors are more effective than other vasodilators in the treatment of patients with congestive heart failure. This gap in knowledge led us to study the biochemical mechanism of Ang II formation in the human heart. Such studies have only recently been addressed. So far, two Ang II-forming enzymes (ACE and human chymase) have been identified. Unlike in the rat heart, the minor (10%) component of Ang II-forming activity in the left ventricle is due to ACE, whereas the major (80%) component is due to human chymase. This novel cardiac serine proteinase has been purified from the human left ventricle and characterized, and recently, the cDNA and the gene for this enzyme have been cloned. Biochemical characterization revealed that human chymase is the most efficient and specific Ang II-forming enzyme described thus far, but the cellular and regional distribution of two Ang II-forming enzymes seem to be quite different. ACE is localized mainly in endothelial cells and its expression level is higher in atria than ventricles whereas chymase is localized in the interstitial region of the myocardium and its expression is higher in ventricles than atria.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Cardiac angiotensin II formation: the angiotensin-I converting enzyme and human chymase. 829 72

This review focuses on the mechanisms whereby the cytosolic Ca2+ regulates the ubiquitous Na+/ H+ exchanger (NHE-1) and how these regulatory processes might modify the behavior of NHE-1 in essential hypertension. The pH setpoint for activation of the Na+/H+ exchanger is controlled by two interrelated and Ca(2+)-dependent pathways, namely, the protein kinase/ phosphatase cascade and Ca2+/calmodulin. The cytoplasmic domain of NHE-1 contains elements responsive to serine/theorine kinases and a high affinity binding site to Ca2+/calmodulin. Phosphorylation of NHE-1 or the binding of the Ca2+/calmodulin complex to its binding site promotes an alkaline shift in the pH setpoint for the exchanger. It is suggested that, in essential hypertension, an increased cellular Ca2+ load or an enhanced external Ca2+ entry stimulate the NHE-1 through protein kinase/phosphatase and Ca2+/calmodulin systems, thereby increasing its activity.
 ...
PMID:The links between cellular Ca2+ and Na+/H+ exchange in the pathophysiology of essential hypertension. 880 85

Reduced ability or failure to stimulate cyclic adenosinemonophosphate (AMP) synthesis on a second addition of hormone 30 min after a first stimulation was taken as an indirect indication of the synthesis of the cyclic AMP antagonist prostaglandylinositol cyclic phosphate (cyclic PIP). In diabetic rats, because of an increased possibility of restimulating cyclic AMP synthesis, the formation of cyclic PIP should be reduced. Additionally, severalfold increased basal cyclic AMP synthesis can be observed in diabetic hepatocytes in comparison with controls. Upon measuring cyclic PIP levels after hormonal stimulation in all organs of diabetic rats, it was found that stimulation of cyclic PIP synthesis by insulin decreased gradually in a time-dependent manner. Plasma membranes were prepared from diabetic Ksj db/db mice and from spontaneously hypertensive rats (SHR), and in a subsequent assay for cyclic PIP synthetase, an up to 60% decrease of enzyme activity was found. Cyclic PIP synthetase can be completely inhibited by preincubation with protein kinase A. It is most likely that this serine phosphorylation reaction by which the enzyme is inhibited also in vivo is a result of increased cyclic AMP levels. The addition of 10(-5)-10(-4) M sulfonylureas to the enzyme assay of liver plasma membrane causes full inhibition, and the addition of 10(-5)-10(-4) M biguanides, a two- to fourfold activation of the enzyme. Activation of cyclic PIP synthetase by biguanides can also be demonstrated in intact cells. It is a fast reaction and additive with respect to the activation by fluoride or guanylyl-imidodiphosphate (GMP-PNP), and it is most likely the effect with which the biguanides produce the correcting changes in metabolism. Furthermore, antihypertensive drugs like captopril, guanethidine, and dihydralazine also activate cyclic PIP synthetase. In contrast to the activation by the biguanides, this effect is not additive to the activation by fluoride. It appears that essential hypertension and type 2 diabetes are connected with or may be the result of a reduction in synthesis of the intracellular messenger cyclic PIP, whose synthesis is stimulated by hormones like insulin and noradrenaline (alpha-adrenergic action).
 ...
PMID:Insulin resistance, a result of reduced synthesis of prostaglandylinositol cyclic phosphate, a mediator of insulin action? Regulation of cyclic PIP synthetase activity by oral antidiabetic and antihypertensive drugs. 945 69

CYP11B1 (11beta-hydroxylase) and CYP11B2 (aldosterone synthase) are 93% identical mitochondrial enzymes that both catalyze 11beta-hydroxylation of steroid hormones. CYP11B2 has the additional 18-hydroxylase and 18-oxidase activities required for conversion of 11-deoxycorticosterone to aldosterone. These two additional C18 conversions can be catalyzed by CYP11B1 if serine-288 and valine-320 are replaced by the corresponding CYP11B2 residues, glycine and alanine. Here we show that such a hybrid enzyme also catalyzes conversion of 11-deoxycortisol to cortisol, 18-hydroxycortisol, and 18-oxocortisol. These latter two steroids are present at elevated levels in individuals with glucocorticoid suppressible hyperaldosteronism (GSH) and some forms of primary aldosteronism. Their production by the recombinant CYP11B enzyme is enhanced by substitution of further amino acids encoded in exons 4, 5, and 6 of CYP11B2. A converted CYP11B1 gene, containing these exons from CYP11B2, would be regulated like CYP11B1, yet encode an enzyme with the activities of CYP11B2, thus causing GSH or essential hypertension. In a sample of 103 low renin hypertensive patients, 218 patients with primary aldosteronism, and 90 normotensive individuals, we found a high level of conversion of CYP11B genes and four cases of GSH caused by unequal crossing over but no gene conversions of the type expected to cause GSH.
 ...
PMID:Recombinant CYP11B genes encode enzymes that can catalyze conversion of 11-deoxycortisol to cortisol, 18-hydroxycortisol, and 18-oxocortisol. 981 82

The mitogen-activated protein (MAP) kinase family members are ubiquitously expressed protein kinases activated in response to a variety of extracellular stimuli and shown to be involved in cell growth, transformation, differentiation and apoptosis. MAP kinases have been implicated in both growth and apoptosis of vascular smooth muscle cells (VSMC) which suggests that they play important roles in cardiovascular diseases such as essential hypertension, atherosclerosis, and restenosis followed angioplasty. The MAP kinases are themselves components of specific kinase cascades characterized by activation by specific stimuli, families of related serine and threonine kinases and downstream substrates that include other kinases, transcription factors, membrane receptors and other cell mediators. Cross-talk among the different MAP kinases results in direct modulation of signal transduction. In addition, increased expression and activation of MAP kinase phosphatases plays an important role in MAP kinase inactivation. Our laboratory has used angiotensin II (AngII), a potent activator of all MAP kinases in VSMC, to study mechanisms by which MAP kinases are regulated by vasoactive peptides. In this review, we describe the mechanisms by which AngII activates MAP kinases, and potential roles for MAP kinases in AngII-dependent effects on VSMC function.
 ...
PMID:MAP kinases and vascular smooth muscle function. 988 83

The ability of the dopamine-1 (D1)-like receptor to stimulate adenylyl cyclase (AC) and phospholipase C (PLC), inhibit sodium transport in the renal proximal tubule (RPT), and produce natriuresis is attenuated in several rat models of hypertension. Since the inhibitory effect of D1-like receptors on RPT sodium transport is also reduced in some patients with essential hypertension, we measured D1-like receptor coupling to AC and PLC in cultures of human RPT cells from normotensive (NT) and hypertensive (HT) subjects. Basal cAMP concentrations were the same in NT (n=6) and HT (n=4). However, the D1-like receptor agonist fenoldopam increased cAMP production to a greater extent in NT (maximum response=67+/-1%) than in HT (maximum response=17+/-5%), with a potency ratio of 105. Dopamine also increased cAMP production to a greater extent in NT (32+/-3%) than in HT (14+/-3%). The fenoldopam-mediated increase in cAMP production was blocked by SCH23390 (a D1-like receptor antagonist) and by antisense D1 oligonucleotides in both HT and NT, indicating action at the D1 receptor. The stimulatory effects of forskolin and parathyroid hormone-related protein of cAMP accumulation were not statistically different in NT and HT, indicating receptor specificity and an intact G-protein/AC pathway. The fenoldopam-stimulated PLC activity was not impaired in HT, and the primary sequence and expression of the D1 receptor were the same in NT and HT. However, D1 receptor serine phosphorylation in the basal state was greater in HT than in NT and was not responsive to fenoldopam stimulation in HT. These studies demonstrate the expression of D1 receptors in human RPT cells in culture. The uncoupling of the D1 receptor in both rats (previously described) and humans (described here) suggests that this mechanism may be involved in the pathogenesis of hypertension; the uncoupling may be due to ligand-independent phosphorylation of the D1 receptor in hypertension.
 ...
PMID:Dopamine-1 receptor coupling defect in renal proximal tubule cells in hypertension. 1020 44

Insulin resistance and hypertension commonly occur together. Pharmacological inhibition of the renin-angiotensin system has been found to reduce not only hypertension, but also insulin resistance. This raises the possibility that the renin-angiotensin system may interact with insulin signalling. We have investigated the relationship between insulin and angiotensin II (AII) intracellular signalling in vivo using an intact rat heart model, and in vitro using rat aorta smooth muscle cells (RASMC). Results generated in the in vivo studies indicate that, like insulin, AII stimulates tyrosine phosphorylation of the insulin receptor substrates IRS-1 and IRS-2. This leads to binding of IRS-1 and IRS-2 to PI3-kinase. However, in contrast to the effect of insulin. IRS-1- and IRS-2-associated PI3-kinase activity is inhibited by AII in a dose-dependent manner. Moreover, AII inhibits insulin-stimulated IRS-1/IRS-2-associated PI3-kinase activity. The in vivo effects of AII are mediated via the AT1 receptor. The results of the in vitro studies indicate that AII inhibits insulin-stimulated, IRS-1-associated PI3-kinase activity by interfering with the docking of IRS-1 with the p85 regulatory subunit of PI3-kinase. It appears that AII achieves this effect by stimulating serine phosphorylation of the insulin receptor beta-subunit IRS-1, and the p85 regulatory subunit of PI3-kinase. These actions result in the inhibition of normal interactions between the insulin signalling pathway components. Thus, we believe that AII negatively modulates insulin signalling by stimulating multiple serine phosphorylation events in the early components of the insulin signalling cascade. Overactivity of the renin-angiotensin system is likely to impair insulin signalling and contribute to insulin resistance observed in essential hypertension.
 ...
PMID:Crosstalk between insulin and angiotensin II signalling systems. 1032 50

Essential hypertension has a heritability as high as 30-50%, but its genetic cause(s) has not been determined despite intensive investigation. The renal dopaminergic system exerts a pivotal role in maintaining fluid and electrolyte balance and participates in the pathogenesis of genetic hypertension. In genetic hypertension, the ability of dopamine and D(1)-like agonists to increase urinary sodium excretion is impaired. A defective coupling between the D(1) dopamine receptor and the G protein/effector enzyme complex in the proximal tubule of the kidney is the cause of the impaired renal dopaminergic action in genetic rodent and human essential hypertension. We now report that, in human essential hypertension, single nucleotide polymorphisms of a G protein-coupled receptor kinase, GRK4gamma, increase G protein-coupled receptor kinase (GRK) activity and cause the serine phosphorylation and uncoupling of the D(1) receptor from its G protein/effector enzyme complex in the renal proximal tubule and in transfected Chinese hamster ovary cells. Moreover, expressing GRK4gammaA142V but not the wild-type gene in transgenic mice produces hypertension and impairs the diuretic and natriuretic but not the hypotensive effects of D(1)-like agonist stimulation. These findings provide a mechanism for the D(1) receptor coupling defect in the kidney and may explain the inability of the kidney to properly excrete sodium in genetic hypertension.
 ...
PMID:G protein-coupled receptor kinase 4 gene variants in human essential hypertension. 1190 38


1 2 3 Next >>