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:3.6.1.3 (ATPase)
65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Increasing evidence suggests that statins may have pleiotropic effects on vascular wall independent of their cholesterol lowering properties. In the present study, we investigated the acute vascular effects of pravastatin, atorvastatin and cerivastatin on rat isolated aortic rings. Statins effectively and comparably relaxed the aortic rings precontracted submaximally with noradrenaline, in a concentration-dependent manner, in which a high potency was observed with cerivastatin. Endothelium removal or incubation of the aortic rings with nitric oxide synthase inhibitor L-NOARG (10(-4) M) and/or cyclooxygenase inhibitor indomethacin (10(-5) M) significantly attenuated the acute vasorelaxation induced by either of statin. Additionally, different from the other two statins, a significant reduction was observed in response to cerivastatin in the presence of KATP channel inhibitor, glibenclamide (10(-5) M) and Na+- K+ ATPase inhibitor, ouabain (10(-4) M). Furthermore, pretreatment of the rings with the cholesterol precursor mevalonate (10(-3) M) significantly inhibited the endothelium-mediated relaxant effects of the statins. Our findings suggest that statins could acutely modulate vascular tone importantly by endothelium-dependent and mevalonate-related pathways.
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PMID:Relaxant effects of pravastatin, atorvastatin and cerivastatin on isolated rat aortic rings. 1569 55

Macrophage fusion leading to formation of multinucleated giant cells during chronic inflammation is poorly understood in mechanism and physiological significance. To address this, we developed a system of human macrophage fusion that utilizes IL-4, IL-13, or alpha-tocopherol to generate large foreign body-type giant cells (FBGC). Extending our previously demonstrated requirements for F-actin and mannose receptor (MR) activity, we find that macrophage fusion exhibits further features of a phagocytic process. Pharmacological inhibition of IL-4-induced FBGC formation indicates critical roles for vacuolar-type ATPase, microtubules, the endoplasmic reticulum (ER), and calcium-independent phospholipase A(2) (iPLA(2)), but not calcium-dependent PLA(2) (cPLA(2)), secretory PLA(2) (sPLA(2)), cyclooxygenase, or lipoxygenase. Immunocytochemistry confirms iPLA(2) expression and absence of cPLA(2) or sPLA(2) expression in macrophages/FBGC. As markers of ER-mediated phagocytosis, calnexin and calregulin are detectable on non-permeabilized fusing macrophages and also concentrated at fusion interfaces where they co-localize with actin in permeabilized macrophages/FBGC. Furthermore, ER markers co-localize with concanavalin A reactivity on non-permeabilized fusing macrophages, suggesting that the ER may present MR ligand during fusion events. These data demonstrate for the first time that the mechanism of macrophage fusion leading to formation of multinucleated giant cells exhibits multiple features of phagocytosis with potential participation of the ER.
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PMID:Multinucleated giant cell formation exhibits features of phagocytosis with participation of the endoplasmic reticulum. 1610 4

We studied the modulation of pacemaker activities by bradykinin in cultured interstitial cells of Cajal (ICC) from murine small intestine with the whole-cell patch-clamp technique. Externally applied bradykinin produced membrane depolarization in the current-clamp mode and increased tonic inward pacemaker currents in the voltage-clamp mode. Pretreatment with bradykinin B1 antagonist did not block the bradykinin-induced effects on pacemaker currents. However, pretreatment with bradykinin B2 antagonist selectively blocked the bradykinin-induced effects. Also, only externally applied selective bradykinin B2 receptor agonist produced tonic inward pacemaker currents and ICC revealed a colocalization of the bradykinin B2 receptor and c-kit immunoreactivities, but bradykinin B1 receptors did not localize in ICC. External Na(+)-free solution abolished the generation of pacemaker currents and inhibited the bradykinin-induced tonic inward current. However, a Cl(-) channel blocker (DIDS) did not block the bradykinin-induced tonic inward current. The pretreatment with Ca(2+)-free solution and thapsigargin, a Ca(2+)-ATPase inhibitor in endoplasmic reticulum, abolished the generation of pacemaker currents and suppressed the bradykinin-induced action. Chelerythrine and calphostin C, protein kinase C inhibitors or naproxen, an inhibitor of cyclooxygenase, did not block the bradykinin-induced effects on pacemaker currents. These results suggest that bradykinin modulates the pacemaker activities through bradykinin B2 receptor activation in ICC by external Ca(2+) influx and internal Ca(2+) release via protein kinase C- or cyclooxygenase-independent mechanism. Therefore, the ICC are targets for bradykinin and their interaction can affect intestinal motility.
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PMID:Bradykinin modulates pacemaker currents through bradykinin B2 receptors in cultured interstitial cells of Cajal from the murine small intestine. 1678 9

Release of bilateral ureteral obstruction (BUO) is associated with reduced expression of renal aquaporins (AQPs), polyuria, and impairment of urine-concentrating capacity. Recently, we demonstrated that 24 h of BUO is associated with increased cyclooxygenase (COX)-2 expression in the inner medulla (IM) and that selective COX-2 inhibition prevents downregulation of AQP2. In the present study, we tested the hypothesis that COX-2 activity increases in the postobstructive phase and that this increase in COX-2 activity contributes to polyuria and impaired urine-concentrating capacity. We examined the effect of the selective COX-2 inhibitor parecoxib (5 mg.kg(-1).day(-1) via osmotic minipumps) on renal functions and protein abundance of AQP2, AQP3, Na-K-2Cl cotransporter type 2 (NKCC2), and Na-K-ATPase 3 days after release of BUO. At 3 days after release of BUO, rats exhibited polyuria, dehydration and urine and IM tissue osmolality were decreased. There were inverse changes of COX-1 and COX-2 in the IM: COX-2 mRNA, protein, and activity increased, while COX-1 mRNA and protein decreased. Parecoxib reduced urine output 1 day after release of BUO, but sodium excretion and glomerular filtration rate were unchanged. Parecoxib normalized urinary PGE(2) and PGI(2) excretion and attenuated downregulation of AQP2 and AQP3, while phosphorylated AQP2 and NKCC2 remained suppressed. Parecoxib did not improve urine-concentrating capacity in response to 24 h of water deprivation. We conclude that decreased NKCC2 and collapse of the IM osmotic gradient, together with suppressed phosphorylated AQP2, are likely causes for the impaired urine-concentrating capacity and that COX-2 activity is not likely to mediate these changes in the chronic postobstructive phase after ureteral obstruction.
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PMID:COX-2 activity transiently contributes to increased water and NaCl excretion in the polyuric phase after release of ureteral obstruction. 1722 76

Strong evidence suggests a mechanistic link between cholesterol metabolism and the formation of amyloid-beta peptides, the principal constituents of senile plaques found in the brains of patients with Alzheimer's disease. Here, we show that several fibrates and diaryl heterocycle cyclooxygenase inhibitors, among them the commonly used drugs fenofibrate and celecoxib, exhibit effects similar to those of cholesterol on cellular membranes and amyloid precursor protein (APP) processing. These drugs have the same effects on membrane rigidity as cholesterol, monitored here by an increase in fluorescence anisotropy. The effect of the drugs on cellular membranes was also reflected in the inhibitory action on the sarco(endo)plasmic reticulum Ca(2+)-ATPase, which is known to be inhibited by excess ordering of membrane lipids. The drug-induced decrease of membrane fluidity correlated with an increased association of APP and its beta-site cleaving enzyme BACE1 with detergent-resistant membranes (DRMs), which represent membrane clusters of substantial rigidity. DRMs are hypothesized to serve as platforms for the amyloidogenic processing of APP. According to this hypothesis, both cholesterol and the examined compounds stimulated the beta-secretase cleavage of APP, resulting in a massive increase of secreted amyloid-beta peptides. The membrane-ordering potential of the drugs was observed in a cell-free assay, suggesting that the amyloid-beta promoting effect was analog to cholesterol due to primary effect on membrane rigidity. Because fenofibrate and celecoxib are widely used in humans as hypolipidemic drugs for prevention of atherosclerosis and as anti-inflammatory drugs against arthritis, possible side effects should be considered upon long-term clinical application.
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PMID:Cholesterol-like effects of selective cyclooxygenase inhibitors and fibrates on cellular membranes and amyloid-beta production. 1739 89

Considering the growing importance of the interaction between components of kallikrein-kinin and renin-angiotensin systems in physiological and pathological processes, particularly in diabetes mellitus, the aim of the present study was to investigate the interaction between angiotensin-(1-7) (Ang-(1-7)) and bradykinin (BK), important components of these systems in an insulin resistance model of diabetes, and the effect of insulin on it. For this the response of mesenteric arterioles of anesthetized neonatal streptozotocin-induced (n-STZ) diabetic and control rats was evaluated using intravital microscopy. Though capable of potentiating BK in non-diabetic rats, Ang-(1-7) did not potentiate BK in n-STZ rats. Chronic but not acute insulin treatment restored the potentiation. This restorative effect of insulin was abolished by a K+ channel blocker (tetraethylammonium), by nitric oxide synthase inhibitor (N-nitro-L-arginine methyl ester) and by a cyclooxygenase inhibitor (indomethacin). On the other hand, Na(+)-,K(+)-ATPase inhibition (by ouabain) did not abolish the effect of insulin. There was no difference in mRNA and protein expression of B1 and B2 kinin receptor subtypes between n-STZ diabetic and control rats. Insulin treatment did not alter the kinin receptor expression. Our data allow us to conclude that diabetes impaired the interaction between BK and Ang-(1-7) and that insulin restores it. The restoring effect of insulin depends on membrane hyperpolarization, nitric oxide release and cyclooxygenease metabolites but not Na+K+-ATPase. Alteration of kinin receptor expression might not be involved in the restoring effect of insulin on the potentiation of BK by Ang-(1-7).
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PMID:Lack of potentiation of bradykinin by angiotensin-(1-7) in a type 2 diabetes model: role of insulin. 1740 6

Several pathologies of the cardiovascular system are associated with an augmented production of nitric oxide and/or superoxide-derived oxidants and/or alteration in the antioxidant detoxification pathways that lead to nitroxidative stress. One important consequence of these reactive intermediates at the biochemical level is the nitration of protein tyrosines, which is performed through either of two of the relevant nitration pathways that operate in vivo, namely peroxynitrite and heme peroxidase-dependent nitration. Proteins nitrated at tyrosine residues have been detected in several compartments of the cardiovascular system. In this review a selection of nitrated proteins in plasma (fibrinogen, plasmin, Apo-1), vessel wall (Apo-B, cyclooxygenase, prostaglandin synthase, Mn-superoxide dismutase) and myocardium (myofibrillar creatine kinase, alpha-actinin, sarcoplasmic reticulum Ca(2+) ATPase) are analyzed in the context of cardiovascular disease. Nitration of tyrosine can affect protein function, which could directly link nitroxidative stress to the molecular alterations found in disease. While some proteins are inactivated by nitration (e.g. Mn-SOD) others undergo a gain-of-function (e.g. fibrinogen) that can have an ample impact on the pathophysiology of the cardiovascular system. Nitrotyrosine is also emerging as a novel independent marker of cardiovascular disease. Pharmacological strategies directed towards inhibiting protein nitration will assist to shed light on the relevance of this post-translational modification to human cardiovascular pathology.
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PMID:Biochemistry of protein tyrosine nitration in cardiovascular pathology. 1754 86

In the mouse macrophage-like cell line RAW 264, vacuolar-type (H(+))-ATPase (V-ATPase) inhibitors, bafilomycin A(1) and concanamycin A, increased the level of cyclooxygenase (COX)-2 protein and its mRNA. The V-ATPase inhibitor-induced expression of COX-2 was suppressed by inhibitors of c-jun N-terminal kinase (JNK) and nuclear factor-kappaB, and by inhibitors of Na(+)/H(+) exchangers (NHEs). The bafilomycin A(1)-induced activation of JNK but not degradation of IkappaB-alpha was suppressed by NHE inhibitors and by an inhibitor of Na(+)/Ca(2+) exchanger SN-6. These results suggested that V-ATPase inhibitors induce the expression of COX-2 via NHE-dependent and -independent pathways.
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PMID:Involvement of Na+/H+ exchangers in induction of cyclooxygenase-2 by vacuolar-type (H+)-ATPase inhibitors in RAW 264 cells. 1782 20

We have previously reported that green tea catechins displayed a potent antithrombotic effect by inhibition of platelet aggregation. In the present study, the antiplatelet and antithrombotic activities of epigallocatechin gallate (EGCG), the major catechin derived from green tea, were extensively investigated. EGCG inhibited arterial thrombus formation and U46619-, collagen-, and arachidonic acid (AA)-induced washed rabbit platelet aggregation in a concentration-dependent manner, with IC50 values of 61 +/- 3, 85 +/- 4, and 99 +/- 4 microM, respectively. In line with the inhibition of collagen-induced platelet aggregation, EGCG revealed blocking of the collagen-mediated phospholipase (PL) Cgamma2 and protein tyrosine phosphorylation, and it caused concentration-dependent decreases of cytosolic calcium mobilization, AA liberation, and serotonin secretion. In addition, the platelet aggregation, intracellular Ca2+ mobilization, and protein tyrosine phosphorylation induced by thapsigargin, a Ca2(+)-ATPase pump inhibitor, were completely blocked by EGCG. Contrary to the inhibition of AA-induced platelet aggregation, EGCG failed to inhibit cyclooxygenase and thromboxane (TX) A2 synthase activities, but it concentration-dependently elevated AA-mediated PGD2 formation. In contrast, epigallocatechin (EGC), a structural analogue of EGCG lacking a galloyl group in the 3' position, slightly inhibited collagen-stimulated cytosolic calcium mobilization, but failed to affect other signal transductions as did EGCG in activated platelets and arterial thrombus formation. These results suggest that antiplatelet activity of EGCG may be attributable to its modulation of multiple cellular targets, such as inhibitions of PLCgamma2, protein tyrosine phosphorylation and AA liberation, and elevation of cellular PGD2 levels, as well as maintaining Ca2(+)-ATPase activity, which may underlie its beneficial effect on the atherothrombotic diseases.
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PMID:Antiplatelet activity of epigallocatechin gallate is mediated by the inhibition of PLCgamma2 phosphorylation, elevation of PGD2 production, and maintaining calcium-ATPase activity. 1820 68

The possible involvement of different effector systems (nitric oxide synthase, guanylate cyclase, beta-adrenergic and muscarinic cholinergic receptors, cyclooxygenase and lipoxygenase, and Na(+),K(+)-ATPase) was evaluated in a histamine H(3) receptor agonist-induced ((R)alpha-methylhistamine, (R)alpha-MeHA) endothelium-dependent rat aorta relaxation assay. (R)alpha-MeHA (0.1 nM - 0.01 mM) relaxed endothelium-dependent rat aorta, with a pD(2) value of 8.22 +/- 0.06, compared with a pD(2) value of 7.98 +/- 0.02 caused by histamine (50% and 70% relaxation, respectively). The effect of (R)alpha-MeHA (0.1 nM - 0.01 mM) was competitively antagonized by thioperamide (1, 10 and 30 nM) (pA(2) = 9.21 +/- 0.40; slope = 1.03 +/- 0.35) but it was unaffected by pyrilamine (100 nM), cimetidine (1 muM), atropine (10 muM), propranolol (1 muM), indomethacin (10 muM) or nordthydroguaiaretic acid (0.1 mM). Inhibitors of nitric oxide synthase, L-N(G)-monomethylarginine (L-NMMA, 10 muM) and N(G)-nitro-L-arginine methylester (L-NOARG, 10 muM) inhibited the relaxation effect of (R)alpha-MeHA, by approximately 52% and 70%, respectively). This inhibitory effect of L-NMMA was partially reversed by L-arginine (10 muM). Methylene blue (10 muM) and ouabain (10 muM) inhibited relaxation (R)alpha-MeHA-induced by approximately 50% and 90%, respectively. The products of cyclooxygenase and lipoxygenase are not involved in (R)alpha-MeHA-induced endothelium-dependent rat aorta relaxation nor are the muscarinic cholinergic and beta-adrenergic receptors. The results also suggest the involvement of NO synthase, guanylate cyclase and Na(+),K(+)-ATPase in (R)alpha-MeHA-induced endothelium-dependent rat aorta relaxation.
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PMID:Endothelium-dependent relaxation of rat aorta to a histamine H(3) agonist is reduced by inhibitors of nitric oxide synthase, guanylate cyclase and Na,K-ATPase. 1847 1


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