Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.6.1.3 (ATPase)
 65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have previously shown that stimulation of acid secretion in parietal cells causes rapid initial cell shrinkage, followed by Na(+)/H(+) exchange-mediated regulatory volume increase (RVI). The factors leading to the initial cell shrinkage are unknown. We therefore monitored volume changes in cultured rabbit parietal cells by confocal measurement of the cytoplasmic calcein concentration. Although blocking the presumably apically located K(+) channel KCNQ1 with chromanol 293b reduced both the forskolin- and carbachol-induced cell shrinkage, inhibition of Ca(2+)-sensitive K(+) channels with charybdotoxin strongly inhibited the cell volume decrease after carbachol, but not after forskolin stimulation. The cell shrinkage induced by both secretagogues was partially inhibited by blocking H(+)-K(+)-ATPase with SCH28080 and completely absent after incubation with NPPB, which inhibits parietal cell anion conductances involved in acid secretion. The subsequent RVI was strongly inhibited with the Na(+)/H(+) exchanger 1 (NHE1)-specific concentration of HOE642 and completely by 500 muM dimethyl-amiloride (DMA), which also inhibits NHE4. None of the above substances induced volume changes under baseline conditions. Our results indicate that cell volume decrease associated with acid secretion is dependent on the activation of K(+) and Cl(-) channels by the respective secretagogues. K(+), Cl(-), and water secretion into the secretory canaliculi is thus one likely mechanism of stimulation-associated cell shrinkage in cultured parietal cells. The observed RVI is predominantly mediated by NHE1.
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PMID:Mechanisms of secretion-associated shrinkage and volume recovery in cultured rabbit parietal cells. 1709 54

[(Dihydroindenyl)oxy]acetic acid (DIOA) has been used as a potent inhibitor of K+ -Cl- cotransporter (IC(50)=10 microM). Here we found that DIOA inhibited activities of P-type ATPases such as dog kidney Na+,K+-ATPase (IC(50)=53 microM), hog gastric H+,K+-ATPase (IC(50)=97 microM) and rabbit muscle Ca(2+)-ATPase (IC(50)=127 microM). In the membrane preparation of the LLC-PK1 cells stably expressing rabbit gastric H+,K+-ATPase, DIOA inhibited activities of the endogenous Na+,K+-ATPase (IC(50)=95 microM) and the exogenous H+,K+-ATPase (IC(50)=75 microM). 5-Nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB), a Cl- channel blocker, had no effects on the DIOA-elicited inhibition of the P-type ATPases. These findings suggest that lower concentration of DIOA (< 20-30 microM) should be used for evaluation of the activity of K+ -Cl- cotransporter without affecting the activities of coexisting Na+,K+ -ATPase and/or H+,K+-ATPase in cells.
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PMID:Inhibition of P-type ATPases by [(dihydroindenyl)oxy]acetic acid (DIOA), a K+ -Cl- cotransporter inhibitor. 1730 13

To date three potential candidates for parietal cell basolateral Cl(-) entry have been described: the highly 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS)-sensitive Cl(-)/HCO(3)(-) exchanger AE2, the HCO(3)(-) and lowly DIDS-sensitive SLC26A7 protein, and the Na(+)-2Cl(-)K(+) cotransporter (NKCC1). In this study we investigate the contribution of these pathways to secretagogue stimulated acid secretion. Individually hand-dissected rat gastric glands were microfluorimetrically monitored for Cl(-) influx and pH(i) changes. Transporter activity was determined by varying ion content and through the use of pharmacological inhibitors. Expression of SLC26A7 in rat parietal cells was shown by immunohistochemistry and Western blot. SLC26A7 was inhibited by 5-Nitro-2-(3-phenylpropyl-amino)benzoic acid (NPPB) (100 microM) in the Xenopus laevis oocyte expression system. Cl(-) influx in parietal cells was enhanced by histamine, depended partially on endogenous HCO(3)(-) synthesis and completely on extracellular Na(+). Removal and subsequent readdition of Cl(-) revealed a low and a high DIDS-sensitive HCO(3)(-) extrusion system contributing to Cl(-) uptake. At acidic pH(i), however, H(+) extrusion via the H(+),K(+)-ATPase depending on Cl(-) uptake was abolished only in the presence of 100 microM (NPPB) and at high (250 microM) DIDS concentration. There was no effect of the NKCC inhibitor bumetanide on stimulated H(+) extrusion. These results would be compatible with SLC26A7 as a Cl(-) uptake system under histamine stimulation.
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PMID:SLC26A7 can function as a chloride-loading mechanism in parietal cells. 1740 55

The interaction between H(+) extrusion via H(+)-ATPase and Cl(-) conductance was studied in the C11 clone of MDCK cells, akin to the intercalated cells of the collecting duct. Cell pH (pHi) was measured by fluorescence microscopy using the fluorescein-derived probe BCECF-AM. Control recovery rate measured after a 20 mM NH(4)Cl acid pulse was 0.136 +/- 0.008 pH units/min (dpHi/dt) in Na(+) Ringer and 0.032 +/- 0.003 in the absence of Na(+) (0 Na(+)). With 0 Na(+) plus the Cl(-) channel inhibitor NPPB (10 microM), recovery was reduced to 0.014 +/- 0.001 dpHi/dt. 8-Br-cAMP, known to activate CFTR Cl(-) channels, increased dpHi/dt in 0 Na(+) to 0.061 +/- 0.009 and also in the presence of 46 nM concanamycin and 50 microM Schering 28080. Since it is thought that the Cl(-) dependence of H(+)-ATPase might be due to its electrogenic nature and the establishment of a +PD (potential difference) across the cell membrane, the effect of 10 microM valinomycin at high (100 mM) K(+) was tested in our cells. In Na(+) Ringer, dpHi/dt was increased, but no effect was detected in 0 Na+ Ringer in the presence of NPPB, indicating that in intact C11 cells the effect of blocking Cl(-) channels on dpHi/dt was not due to an adverse electrical gradient. The effect of 100 microM ATP was studied in 0 Na(+) Ringer solution; this treatment caused a significant inhibition of dpHi/dt, reversed by 50 microM Bapta. We have shown that H(+)-ATPase present in MDCK C11 cells depends on Cl(-) ions and their channels, being regulated by cAMP and ATP, but not by the electrical gradient established by electrogenic H(+) transport.
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PMID:Cl- and regulation of pH by MDCK-C11 cells. 1746 31

Mutations in striated muscle alpha-tropomyosin (alpha-TM), an essential thin filament protein, cause both dilated cardiomyopathy (DCM) and familial hypertrophic cardiomyopathy. Two distinct point mutations within alpha-tropomyosin are associated with the development of DCM in humans: Glu40Lys and Glu54Lys. To investigate the functional consequences of alpha-TM mutations associated with DCM, we generated transgenic mice that express mutant alpha-TM (Glu54Lys) in the adult heart. Results showed that an increase in transgenic protein expression led to a reciprocal decrease in endogenous alpha-TM levels, with total myofilament TM protein levels remaining unaltered. Histological and morphological analyses revealed development of DCM with progression to heart failure and frequently death by 6 months. Echocardiographic analyses confirmed the dilated phenotype of the heart with a significant decrease in the left ventricular fractional shortening. Work-performing heart analyses showed significantly impaired systolic, and diastolic functions and the force measurements of cardiac myofibers revealed that the myofilaments had significantly decreased Ca(2+) sensitivity and tension generation. Real-time RT-PCR quantification demonstrated an increased expression of beta-myosin heavy chain, brain natriuretic peptide, and skeletal actin and a decreased expression of the Ca(2+) handling proteins sarcoplasmic reticulum Ca(2+)-ATPase and ryanodine receptor. Furthermore, our study also indicates that the alpha-TM54 mutation decreases tropomyosin flexibility, which may influence actin binding and myofilament Ca(2+) sensitivity. The pathological and physiological phenotypes exhibited by these mice are consistent with those seen in human DCM and heart failure. As such, this is the first mouse model in which a mutation in a sarcomeric thin filament protein, specifically TM, leads to DCM.
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PMID:Dilated cardiomyopathy mutant tropomyosin mice develop cardiac dysfunction with significantly decreased fractional shortening and myofilament calcium sensitivity. 1755 58

Excessive gastric acid secretion plays an important role in the pathogenesis of peptic ulcers. Dexamethasone, a widely used drug, is known to stimulate gastric acid secretion and increase the incidence of peptic ulcers. However little is known about the mechanism of the dexamethasone's effect on parietal cells. The present study was performed to investigate the contribution of the phosphatidylinositol-3-kinase (PI3 kinase) to dexamethasone induced stimulation of gastric acid secretion. In vivo pretreatment with dexamethasone injections (150 microg/100g for 3 days) or in vitro exposure to (10 microM for > 20 minutes) significantly increased acid secretion in isolated gastric glands approximately 2-3 fold. The dexamethasone induced stimulation of gastric acid secretion was concentration dependent and significantly blunted by the H+/K2+ ATPase inhibitor omeprazole (200 microM), the PI3 kinase inhibitor Wortmannin (500 nM), the protein kinase inhibitor staurosporine (2.5 microM) and the Cl(-) channel blocker NPPB (100 microM); but not by the H(2) antagonist cimetidine (100 microM). In conclusion, it was observed that dexamethasone's effect on proton extrusion requires the activity of a PI3 kinase pathway, an apical Cl(-) channel and the H2+/K2+ ATPase.
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PMID:PI3 kinase dependent stimulation of gastric acid secretion by dexamethasone. 1776 79

We investigated the effects of partial left ventricular unloading on failing rat hearts by using heterotopic heart-lung transplantation model. Heart failure (HF) was induced in Lewis rats by ligating the left anterior descending artery. After four weeks, the infarcted hearts and lungs were harvested and transplanted into the recipient rats by anastomosing donor's ascending aorta to recipient's abdominal aorta. Therefore, coronary venous blood entered the left ventricle (LV) and LV was partially unloaded (HF-PU group). Normal and infarcted heart rats (HF group) without transplantation served as control animals. After two weeks' unloading, the infarcted LV in HF-PU group significantly decreased its weight and myocardial diameter compared with HF group and they were close to normal levels. Developed tension of posterior papillary muscle was significantly increased in HF-PU group compared with HF group. The mRNA expressions of brain natriuretic peptide (BNP), sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA2a), beta(1) and beta(2)-adrenergic receptors (beta(1) and beta(2)-AR) in LV tissue were almost normalized in HF-PU group. Partial left ventricular unloading regressed myocardial hypertrophy, reversed contractile dysfunction and normalized the mRNA (BNP, SERCA2a, beta(1) and beta(2)-AR) expressions of failing rat hearts.
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PMID:Partial left ventricular unloading reverses contractile dysfunction and helps recover gene expressions in failing rat hearts. 1800 56

Hypertension induced by high-salt diet in Dahl salt-sensitive rats leads to compensatory cardiac hypertrophy by approximately 11 wk, cardiac dysfunction at approximately 17 wk, and death from cardiac dysfunction at approximately 21 wk. It is unclear what molecular hallmarks distinguish the compensatory hypertrophy from the decompensated cardiac dysfunction phase. Here we compared the gene expression in rat cardiac tissue from the compensatory hypertrophic phase (11 wk, n = 6) with the cardiac dysfunction phase (17 wk, n = 6) and with age-matched normotensive controls. Messenger RNA levels of 93 genes, selected based on predicted association with cardiac dysfunction, were measured by quantitative real-time PCR. In the hypertrophic phase, the expression of three genes, atrial natriuretic peptide (ANP; P = 0.0089), brain natriuretic peptide (P = 0.0012), and endothelin-1 precursor (P = 0.028), significantly increased, whereas there was decreased expression of 24 other genes including SOD2 (P = 0.0148), sarco(endo)plasmic reticulum Ca(2+)-ATPase 2a (P = 0.0002), and ryanodine receptor 2 (P = 0.0319). In the subsequent heart cardiac dysfunction phase, the expression of an additional 20 genes including inducible nitric oxide synthase (NOS; P = 0.0135), angiotensin I-converting enzyme (P = 0.0082), and IL-1beta (P < 0.0001) increased, whereas the expression of seven genes decreased compared with those of age-matched controls. Furthermore, the expression of 22 genes, including prepro-endothelin-1, ANP, angiotensin I-converting enzyme, beta(1)-adrenergic receptor, SOD2, and endothelial NOS, significantly changed in the cardiac dysfunction phase compared with the compensatory hypertrophic phase. Finally, principal component analysis successfully segregated animals with decompensatory cardiac dysfunction from controls, as well as from animals at the compensated hypertrophy phase, suggesting that we have identified molecular markers for each stage of the disease.
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PMID:Alteration of gene expression during progression of hypertension-induced cardiac dysfunction in rats. 1848 46

A fundamental question in physiology is how hormones regulate the functioning of a cell or organ. It was therefore the aim of this study to investigate the effect(s) of BNP-32 on calcium handling by ventricular myocytes obtained from the rat left ventricle. We specifically tested the hypothesis that BNP-32 decreased the L-type calcium current (I(Ca,L)). Perforated patch clamp technique was used to record I(Ca,L) and action potential (AP) in voltage and current clamp mode, respectively. Myocyte shortening was measured using a photodiode array edge-detection system and intracellular calcium transients were measured by fluorescence photometry. Western blotting was used to determine the relative change in the expression of proteins. At the concentrations tested, BNP-32 significantly decreased cell shortening in a dose-dependent manner; increased the phase II slope of the AP by 53.0%; increased the APD(50) by 16.9%; reduced the I(Ca,L) amplitude with a 22.9% decrease in the peak amplitude and reduced Ca(2+)-dependent inactivation; increased the V(1/2) activation of the L-type calcium channel by 51.1% and decreased V(1/2) inactivation by 31.8%; and, intracellular calcium transient amplitude was significantly decreased by 32.0%, whereas the time to peak amplitude and T(1/2) were both significantly increased by 38.7% and 89.4% respectively. Sarcoplasmic reticulum Ca(2+)-ATPase (SERCA2a) protein expression was reduced by BNP-32. These data suggest that BNP-32 regulates ventricular myocyte function by attenuating I(Ca,L), altering the AP and reducing SERCA2a activity and/or expression. This study suggests a novel constitutive mechanism for the autocrine action of BNP on the L-type calcium channel in ventricular myocytes.
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PMID:B-type natriuretic peptide (BNP) attenuates the L-type calcium current and regulates ventricular myocyte function. 1861 64

Abnormal excitation-contraction coupling is a key pathophysiologic component of heart failure (HF), and at a molecular level reduced expression of the sarcoplasmic reticulum (SR) Ca(2+) ATPase (SERCA2a) is a major contributor. Previous studies in small animals have suggested that restoration of SERCA function is beneficial in HF. Despite this promise, the means by which this information might be translated into potential clinical application remains uncertain. Using a recently established cardiac-directed recirculating method of gene delivery, we administered adeno-associated virus 2 (AAV2)/1SERCA2a to sheep with pacing-induced HF. We explored the effects of differing doses of AAV2/1SERCA2a (low 1 x 10(10) d.r.p.; medium 1 x 10(12) d.r.p. and high 1 x 10(13) d.r.p.) in conjunction with an intra-coronary delivery group (2.5 x 10(13) d.r.p.). At the end of the study, haemodynamic, echocardiographic, histopathologic and molecular biologic assessments were performed. Cardiac recirculation delivery of AAV2/1SERCA2a elicited a dose-dependent improvement in cardiac performance determined by left ventricular pressure analysis, (+d P/d t(max); low dose -220+/-70, P>0.05; medium dose 125+/-53, P<0.05; high dose 287+/-104, P<0.05) and echocardiographically (fractional shortening: low dose -3+/-2, P>0.05; medium dose 1+/-2, P>0.05; high dose 6.5+/-3.9, P<0.05). In addition to favourable haemodynamic effects, brain natriuretic peptide expression was reduced consistent with reversal of the HF molecular phenotype. In contrast, direct intra-coronary infusion did not elicit any effect on ventricular function. As such, AAV2/1SERCA2a elicits favourable functional and molecular actions when delivered in a mechanically targeted manner in an experimental model of HF. These observations lay a platform for potential clinical translation.
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PMID:Recirculating cardiac delivery of AAV2/1SERCA2a improves myocardial function in an experimental model of heart failure in large animals. 1934 20


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