Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Adrenomedullin recently has been found to potently stimulate cAMP formation in cultured rat vascular smooth muscle cells (VSMCs). In the present study, we examined the effect of adrenomedullin on the production of a vasoconstrictive and growth-promoting peptide, endothelin-1, after stimulation with a clotting enzyme, thrombin, and a potent mitogen, platelet-derived growth factor (PDGF), in cultured rat VSMCs. Thrombin and PDGF stimulated endothelin-1 production in a dose-dependent manner. Rat adrenomedullin significantly inhibited thrombin- and PDGF-stimulated endothelin-1 production in a dose-dependent manner between 10(-7) and 10(-9) mol/L. Inhibition by rat adrenomedullin of thrombin- and PDGF-stimulated endothelin-1 production was paralleled by an increase in the cellular level of cAMP. Human adrenomedullin also inhibited thrombin- and PDGF-stimulated endothelin-1 production and increased cAMP levels. The addition of 8-bromo-cAMP, a cAMP analogue, reduced thrombin- and PDGF-induced endothelin-1 production. Furthermore, forskolin, a potent activator of adenylate cyclase, reduced thrombin- and PDGF-induced endothelin-1 production. In contrast, basal production of endothelin-1 was not altered by rat or human adrenomedullin. These results indicate that adrenomedullin inhibits not basal but thrombin- and PDGF-induced ET-1 production in cultured VSMCs probably through a cAMP-dependent process. Taken together with the finding that adrenomedullin is synthesized in and secreted from vascular endothelial cells, adrenomedullin may modulate vascular tone as a paracrine regulator partially through the inhibition of VSMC endothelin-1 production in some pathophysiological states.
Hypertension 1995 Jun
PMID:Inhibition of endothelin production by adrenomedullin in vascular smooth muscle cells. 776 61

We have previously reported that addition of 8-bromocyclic AMP enhances the stimulatory effect of dexamethasone on the expression of the angiotensinogen gene in mouse hepatoma cells in vitro. Isoproterenol is known to stimulate the synthesis of hepatic intracellular cyclic AMP via beta-adrenergic receptors. To study the possible effect of beta-adrenergic receptors on the expression of the angiotensinogen gene in mouse hepatoma cells, we transiently transfected them with a fusion gene with the 5'-flanking region of the angiotensinogen gene linked to a bacterial chloramphenicol acetyltransferase coding sequence as a reporter, pOCAT (ANG N-1498/+18). The addition of isoproterenol (10(-9) to 10(-5) mol/L) alone had no stimulatory effect on the expression of pOCAT (ANG N-1498/+18). In the presence of dexamethasone (10(-6) mol/L), however, isoproterenol enhanced the stimulatory effect on the dexamethasone on the expression of pOCAT (ANG N-1498/+18). The enhancing effect of isoproterenol was inhibited by the presence of propranolol (beta 1- and beta 2-adrenergic receptor antagonist) and ICI 118,551 (beta 2-adrenergic receptor antagonist) but not by the presence of atenolol (beta 1-adrenergic receptor antagonist). Furthermore, the addition of Rp-cAMP (an inhibitor of protein kinase A I and II) blocked the enhancing effect of isoproterenol. These studies demonstrated that isoproterenol enhances the stimulatory effect of dexamethasone on the expression of the angiotensinogen gene in mouse hepatoma cells via beta 2-adrenergic receptor and cyclic AMP-dependent protein kinase pathways. Our data may be important in understanding the molecular mechanism(s) of the stimulatory effect of catecholamines/glucocorticoid-induced expression of the angiotensinogen gene in the liver.
Hypertension 1995 Jan
PMID:Beta-adrenergic receptors and angiotensinogen gene expression in mouse hepatoma cells in vitro. 784 40

It is well-known that atherosclerotic change and hypertension are common manifestations in patients with glucocorticoid excess. We previously reported that pituitary adenylate cyclase activating polypeptide (PACAP), prostaglandin E2 (PGE2) and carbacyclin, a stable analog of prostacyclin, have suppressive effects on vasopressin-induced DNA synthesis of rat aortic smooth muscle cells through cAMP production (Murase et al., J. Hypertens., 10 (1992) 1505; Oiso et al., Biochem. Cell. Biol., 71 (1993) 156). In the present study, we investigated the effect of glucocorticoid on cAMP production induced by PACAP, PGE2 and carbacyclin in aortic smooth muscle cells. The pretreatment with dexamethasone significantly inhibited cAMP accumulation induced by these vasoactive agents in a dose dependent manner in the range between 10 pM and 10 nM. These inhibitory effects of dexamethasone were dependent on the time of pretreatment up to 8 h. Dexamethasone inhibited cAMP accumulation induced by NaF, a GTP-binding protein activator, and forskolin which directly activates adenylate cyclase. Moreover, forskolin-induced adenylate cyclase activity was significantly reduced in membranes prepared from the cells treated with dexamethasone. These results strongly suggest that glucocorticoid inhibits cAMP production induced by vasoactive agents in primary cultured rat aortic smooth muscle cells and the inhibitory effect is exerted at the level of adenylate cyclase.
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PMID:Glucocorticoid inhibits cAMP production induced by vasoactive agents in aortic smooth muscle cells. 785 72

Cardiac beta-adrenergic signal transduction was examined in chronic portal vein-stenosed rats. Basal tension and maximum rate of tension development were significantly depressed in left ventricular papillary muscles (0.21 +/- 0.03 N/cm2 and 8.2 +/- 1.7 N.s-1.cm-2, respectively) compared with sham-operated controls (0.51 +/- 0.05 N/cm2 and 19.9 +/- 4.4 N.s-1.cm-2, respectively). The positive inotropic response to isoproterenol was also attenuated. Adenosine 3',5'-cyclic monophosphate formation was decreased significantly when GTP (-41.9%), isoproterenol with GTP (-45.3%), or guanosine 5'-O-(3-thiotriphosphate) (-52.4%) was used to stimulate adenylyl cyclase, but not when Mn2+ or forskolin was used. Beta-Adrenoceptor density (sham operated 24.6 +/- 2.0 fmol/mg; portal vein stenosed 26.4 +/- 2.1 fmol/mg) and the apparent dissociation constant (sham operated 0.26 +/- 0.04 nM; portal vein stenosed 0.29 +/- 0.04 nM) were unaffected. Portal venous hypertension did not alter beta-adrenergic receptor affinity for isoproterenol. However, it was necessary for isoproterenol to occupy three times the number of receptors in papillary muscles from stenosed animals to produce an equal increase in force generation. These data suggest that although portal vein stenosis does not alter cardiac beta-adrenoceptor density or affinity for ligands, transduction of the signal between the receptor and adenylyl cyclase is adversely influenced and may be responsible for the diminished responsiveness of beta-adrenoceptors in the myocardium.
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PMID:Cardiac beta-adrenoceptor-effector coupling in portal vein-stenosed rats. 790 Aug 2

Adrenomedullin is a potent hypotensive peptide newly discovered in pheochromocytoma tissue by monitoring its elevating activity on platelet cAMP. We measured plasma concentration of adrenomedullin in patients with essential hypertension and chronic renal failure. As compared with normal subjects, plasma adrenomedullin was increased by 26% (P < 0.05) in hypertensives without organ damage and by 45% (P < 0.005) in those with organ damage. The increase in plasma adrenomedullin was more prominent in renal failure than in hypertension. Renal failure patients with plasma creatinine of 1.5-3, 3-6, and > 6 mg/dl had higher plasma adrenomedullin levels than healthy subjects by 78% (P < 0.05), 131% (P < 0.001), and 214% (P < 0.001), respectively. Moreover, adrenomedullin showed intimate correlations with norepinephrine, atrial natriuretic peptide, and cAMP in plasma (r = 0.625, P < 0.001; r = 0.656, P < 0.001; and r = 0.462, P < 0.001; respectively). Thus, plasma adrenomedullin is supposed to increase in association with changes in sympathetic nervous activity and body fluid volume in hypertension and renal failure. Considering its potent vasodilator effect, adrenomedullin may be involved in the defense mechanism preserving the integrity of the cardiovascular system in these disorders.
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PMID:Plasma levels of adrenomedullin, a newly identified hypotensive peptide, in patients with hypertension and renal failure. 796 64

Knowledge continues to grow on the biology of endogenous erythropoietin (EPO), its effects on red blood cell physiology, and the use of the recombinant form of the hormone. In addition to oxygen delivery, oxygen consumption may be important in stimulating EPO production. This production is likely mediated by an intracellular messenger system other than cAMP. Once released, EPO prevents programmed cell death of BFU-E and CFU-E cells. Recent evidence suggests that lack of EPO, rather than the presence of EPO inhibitors, is the cause of the anemia seen in renal patients. Recombinant EPO has been available clinically since mid 1989. Nearly two thirds of dialysis patients are receiving this agent, although low doses are the rule, with the average hematocrit achieved of only 31%. EPO dosing has been subjected to kinetic modeling that has revealed a wide range in RBC half-life from patient to patient. This accounts in part for the varying maintenance dosing requirements. An additional modulating factor in the response to EPO is severe, secondary hyperparathyroidism with bone marrow fibrosis which may be reversible with medical or surgical parathyroidectomy. Hypertension continues to occur in 20-35% of patients given EPO. This effect may be mediated by endothelin which appears to be stimulated by EPO administration. Treatment of the anemia of renal failure leads to many organ system benefits including improved muscle metabolism, decreased left ventricular hypertrophy, enhanced immune responses to hepatitis vaccine, and improved brain electrophysiology. he optimal target hematocrit to achieve the greatest benefits for the patient at an acceptable cost remains to be determined.
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PMID:Erythropoietin overview--1993. 798 77

A nuclear extract from petioles of sweet potato protected several sites in the 5'-upstream region of a gene for beta-amylase from DNase I digestion. One of these sites, located at a region around 800-base pairs upstream from the transcription start site, having an imperfect palindromic sequence of CGTCACGTCACG, was designated the R-box. The site contained tandemly duplicated CGTCA sequences, referred to below as 5'- and 3'-CGTCA. Competition experiments in gel mobility shift assays with mutant R-box oligonucleotides indicated that mutations in bases outside the 3'-CGTCA of the R-box do not severely affect the binding. By contrast, single-base substitutions in any one base of the 3'-CGTCA greatly abolished the binding even when the mutated R-boxes contained intact 5'-CGTCA. However, oligonucleotides with mutations in the 3'-CGTCA had the ability to bind the nuclear factor when additional mutations were introduced to create a partially palindromic sequence containing the CGTCA sequence in its 3'-half on the opposite strand. These results indicate that the CGTCA sequence alone is not sufficient for the binding of the R-box binding factor (RBF) and that the RBF binds to the sequence with partial dyad symmetry that contains the CGTCA motif in its 3'-half. The optimum sequence for the binding of the RBF is suggested to be a palindromic octameric sequence TGACGTCA, which is identical to the consensus sequence of the cAMP-responsive element (CRE) of animal genes. Bacterially produced HBP-1b of wheat bound to the R-box, and its binding to mutated R-boxes was similar to that of RBF, suggesting that the RBF belongs to a family of bZIP-type plant nuclear factors that bind to CGTCA-related sequences. However, several differences between the RBF and HBP-1b were also noted.
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PMID:A nuclear factor that binds to a dyad-symmetric sequence with a CGTCA motif in the 5'-upstream region of the sweet potato beta-amylase gene. 802 23

Renal alpha 2-adrenoreceptors modulate the hydrosmotic action of arginine vasopressin (AVP) through suppression of AVP-stimulated adenosine 3',5'-cyclic monophosphate (cAMP) accumulation. Circulating catecholamines, likely candidates for the endogenous ligand, are elevated during cold exposure (CE). These studies therefore tested the hypothesis that the diuresis observed with acute CE in rats is due in part to modulation of AVP's tubular action via alpha 2-adrenoceptor activation. Subjects were five male Brattleboro homozygous diabetes insipidus (DI) rats (358 +/- 8 g) receiving chronic AVP replacement (1 microgram.kg-1 x day-1) and seven Long-Evans (LE) normal rats (395 +/- 5 g). In a CE protocol, baseline measurements at room temperature (RT, 24 +/- 0.3 degrees C) were followed by 60-min exposure to 5 +/- 0.5 degrees C. Results were compared with those from a RT time control protocol. The selective alpha 2-antagonist yohimbine (YOH; 10 micrograms.kg-1 x min-1) or vehicle (VEH) was infused throughout the CE and RT protocols. In VEH-infused rats, CE increased urine flow by 63 +/- 12 (DI rats) and 31 +/- 4 microliters.min-1 x 100 g body wt-1 (LE rats), and mean arterial pressure by 36 +/- 1 (DI rats) and 32 +/- 2 mmHg (LE rats). The increased flow was largely a water diuresis, with changes in free water clearance averaging 45 +/- 11 (DI rats) and 28 +/- 3 microliters.min-1 x 100 g body wt-1 (LE rats). YOH treatment completely blunted the cold-induced diuresis in both strains but did not alter the CE-induced hypertension. Glomerular filtration rate was not affected by either CE or YOH infusion.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Alpha 2-adrenoceptor antagonism attenuates the diuretic response to acute cold exposure. 810 4

The renin angiotensin system plays a major role in the control of blood pressure and electrolyte balance. It consists of a cascade of proteolytic cleavages leading to the biologically active angiotensin II (AII). Renin acts on angiotensinogen to yield angiotensin I (AI). AI is a prohormone and must be cleaved to the octapeptide AII by the action of the angiotensin I converting enzyme. Application of recombinant DNA technology has made possible the cloning of the renin gene and its cDNA which has provided newer insights into the regulation of renin gene expression, biosynthesis, and secretion. The information gained from such molecular biology techniques may contribute importantly to the efforts in the development of an effective renin inhibitor for the treatment of hypertension. The mouse and rat renin gene contains nine exons separated by eight intervening sequences, in contrast the human renin gene contains ten exons separated by nine introns. However, the renin gene of the three species spans 12 kb approximately. In its 5' flanking region, major control elements are present which include promotors and enhancers as well as regulatory elements such as estrogen and glucocorticoid receptor sites, and cAMP induction sequences. The combined action of these elements will result in tissue specific expression and regulation of the gene. In addition to the control at the gene expression level, renin is also regulated at the post-translational and secretory levels. The translational product of renin mRNA is preprorenin, which is cotranslationally cleaved to prorenin, an inactive precursor of renin. The majority of the new synthesized human prorenin is constitutively secreted. However, prorenin is also processed intracellularly and converted to the mature single chain active renin which is stored in secretory granules. Active renin is released by a regulated mechanism which can be stimulated by cAMP and other secretagogues. Studies are under way to examine the responses of renin gene expression, biosynthesis and secretion to various physiological conditions and to determine if there are alterations in the structure and expression of the renin gene that may be involved in the development of clinical and experimental hypertension.
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PMID:[Renin: structure and expression regulation of the gene, biosynthesis, and cellular pathways of secretion]. 821 Jul 68

Corticotropin-releasing factor (CRF), the key neuropeptide in the stress cascade, has major inhibitory actions on testicular function in addition to its known antireproductive effects at the central level (inhibition of sexual behavior and LH secretion). CRF is secreted by the Leydig cells of the testis and acts through high-affinity receptors at the Leydig cell membrane as a potent negative regulator of LH action, inhibiting gonadotropin-induced cAMP generation and androgen production. CRF is also a primary stimulus of beta-endorphin secretion by the Leydig cells, which in turn exerts paracrine inhibition of FSH action in the tubular compartment of the testis through high-affinity receptors in the Sertoli cells. CRF action in the Leydig cells involves a pertussis toxin-insensitive guanyl nucleotide regulatory unit. In contrast to CRF receptors in the brain, pituitary, and other peripheral tissues, those in the Leydig cell are not coupled to Gs. The inhibitory action of CRF in the Leydig cell is exerted through protein kinase C, at the level of the catalytic subunit of adenylate cyclase. The secretion of CRF by the Leydig cell is stimulated by LH, acting via release of serotonin (5HT) and autocrine activation of 5HT2 receptors. Serotonin acts on 5HT2 receptors in the Leydig cell to stimulate CRF secretion via a pertussis toxin insensitive G-protein and presumably through activation of phosphoinositide hydrolysis. The diversity of the biochemical responses to CRF and 5HT2 receptor activation (i.e., inhibition of adenylate cyclase at the cytoplasmic aspect of the cell membrane vs. stimulation of CRF release from secretion granules) may reflect the stimulation of different protein kinase C isoenzymes. The LH-->5HT-->CRF inhibitory loop serves to continuously buffer the stimulation of androgen production by gonadotropin. 5HT, the immediate stimulus of testicular CRF secretion, is released during stress and is locally increased in the testis in pathological conditions associated with impaired testicular function (i.e., orchitis, varicocele). Also, propranolol, the beta-adrenergic antagonist frequently used in the control of blood pressure in patients with hypertension and often associated with impotence, acts via a serotonergic mechanism to stimulate CRF secretion and causes marked inhibition of LH-induced cAMP production and steroidogenesis in cultured Leydig cells. These basic studies of 5HT and CRF are relevant to the pathogenesis of testicular dysfunction and for the development of antagonist therapies to block CRF production and its local antireproductive effects.
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PMID:Corticotropin-releasing factor: an antireproductive hormone of the testis. 838 38


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