bluuebunny/crossref_metadata_2025_split huggingface dataset:
Endogenous asymmetrical dimethylarginine and hypertension associated with puromycin nephrosis in the rat
Authors: Sato Jun , Masuda Hiroshi , Tamaoki Satoru , Hamasaki Hidehisa , Ishizaka Kazuhiro , Matsubara Osamu , Azuma Hiroshi 
Published: January 2005

The present experiments were designed to investigate the role of asymmetrical NG,NG‐dimethyl‐L‐arginine (ADMA) in causing hypertension associated with the focal and segmental glomerulosclerosis (FSGS) produced by a single bolus of puromycin aminonucleoside (PAN) and successive injection of protamine for 7 days in rats which had undergone unilateral nephrectomy.
After the unilateral nephrectomy, and administering PAN and protamine, histological examinations of the kidney revealed a typical FSGS, that is, evident abnormalities including segmental mesangial proliferation, obliteration of glomerular capillary lumens and adhesions between the glomerulus and Bowman's capsule could be observed. Changes in the glomerular epithelial cells consisted of the swelling with bleb formation.
In the FSGS rats, urine volume and urinary protein were significantly (P<0.05 and P<0.005) increased throughout 4‐week experimental period, while the creatinine clearance was significantly (P<0.005) and transiently decreased, and recovered 4 weeks later. These changes were associated with the sustained elevation of the systolic blood pressure.
ADMA levels in aortic endothelial cells, plasma and urine were significantly (P<0.05 and P<0.005) increased in the FSGS rats, but the level in the kidney remained unchanged.
The basal level and net production of cyclic GMP in the aortic vessel wall with endothelium when stimulated by norepinephrine and acetylcholine were significantly (P<0.05 and P<0.01) attenuated in the FSGS rats.
There were significant and positive correlations between systolic blood pressure (y) and ADMA levels (x) in endothelial cells (y=4.43x+122.2, r=0.979, P<0.0001), plasma (y=0.10x+71.9, r=0.921, P<0.001) and urine (y=0.48x+126.9, r=0.699, P<0.005), but not significant in the kidney (y=0.06x+102.7, r=0.252, NS).
These findings suggest that ADMA as an endogenous inhibitor of NO synthesis may play an important role for the pathogenesis in the hypertension associated with the experimental FSGS in the rat.

British Journal of Pharmacology (1998) 125, 469–476; doi:10.1038/sj.bjp.0702101
Increased response to big endothelin‐1 in atherosclerotic human coronary artery: functional evidence for up‐regulation of endothelin‐converting enzyme activity in disease
Authors: Maguire Janet J , Davenport Anthony P 
Published: January 2005

Overproduction of the potent vasoconstrictor peptide endothelin‐1 (ET‐1) is implicated in the pathogenesis of coronary artery disease. In endothelium‐denuded human coronary arteries the response to big ET‐1 was significantly enhanced in atherosclerotic arteries (coronary artery disease, CAD; n=7) with an EC50 value of 96 nM (57–161 nM, 95% C.I.) compared to 274 nM (205–365 nM) in non‐diseased arteries (dilated cardiomyopathy, DCM; n=10) (Mann‐Whitney U‐test, P<0.05). Higher levels of immunoreactive endothelin (ET) could be detected by radioimmunoassay in bathing medium taken from CAD arteries than from DCM arteries (2.8±0.5 nM, n=5 vs 1.1±0.2 nM, n=7) (Student's two‐tailed t‐test, P<0.05). There were no differences in responses of arteries from either group to ET‐1 (EC50 10 nM, CAD vs 14 nM, DCM). The enhanced response of atherosclerotic human coronary arteries to big ET‐1 appears to be due to up‐regulation of endothelin‐converting enzyme (ECE) activity rather than to an augmented response of the arteries to ET‐1. This non‐endothelial ECE may therefore be an important therapeutic target in coronary artery disease.British Journal of Pharmacology (1998) 125, 238–240; doi:10.1038/sj.bjp.0702102
EB1089, a synthetic analogue of vitamin D, induces apoptosis in breast cancer cells in vivo and in vitro
Authors: James Sharon Y. , Mercer Elizabeth , Brady Matthew , Binderup Lise , Colston Kay W. 
Published: January 2005

Effects of the synthetic vitamin D analogue EB1089 on indices of apoptosis in cultured human breast cancer cells and in nitrosomethylurea‐induced rat mammary tumours in vivo were investigated.
At a dose of 0.5 μg kg−1 body weight, EB1089 caused significant inhibition of tumour progression over the 28 day treatment period in the absence of a significant increase in serum calcium concentration. Higher doses of EB1089 (1 and 2.5 μg kg−1) produced substantial regression of the experimental tumours which was accompanied by a striking change in the histological appearance of tumours consistent with induction of tumour cell death.
Fragmentation of genomic DNA is a characteristic feature of apoptosis. With the terminal transferase (TdT) assay, 3′ DNA breaks indicative of DNA fragmentation were detected histochemically in mammary tumour cells from animals treated with EB1089 (2.5 μg kg−1) for 14 days.
Effects of the vitamin D analogue on induction of apoptosis were examined in vitro using the MCF‐7 human breast cancer cell line. Using the TUNEL method, positive nuclear staining indicative of DNA fragmentation was detected in cells treated for 4 days with 10 nM EB1089. Apoptosis was also quantitated using a cell death ELISA which revealed a time and dose dependent induction of apoptosis by EB1089.
The effects of EB1089 on the expression of two oncoproteins which may regulate apoptosis, bcl‐2 and bax were examined by Western analysis. In MCF‐7 cell cultures treated with 1,25(OH)2D3 or EB1089 (1×10−8 M), bcl‐2 protein levels were decreased in a time‐dependent manner relative to control levels. In contrast bax protein was not markedly regulated by these compounds. Densitometric analyses indicate that the vitamin D compounds lower the bcl‐2/bax ratio favouring increased susceptibility of MCF‐7 cells to undergo apoptosis.
These results suggest that the synthetic vitamin D analogue EB1089 may promote tumour regression by inducing active cell death.

British Journal of Pharmacology (1998) 125, 953–962; doi:10.1038/sj.bjp.0702103
Expression of cyclo‐oxygenase‐2 in human airway smooth muscle is associated with profound reductions in cell growth
Authors: Belvisi Maria G. , Saunders Michael , Yacoub Magdi , Mitchell Jane A. 
Published: January 2005

It is now accepted that uncontrolled proliferation of human airway smooth muscle (HASM) cells contributes, in many cases, to the chronic stages of asthma. However, the physiological and pathophysiological processes regulating cell growth and division in the airway are not clear. We have recently shown that the immediate early gene, cyclo‐oxygenase‐2, is induced by cytokines in HASM cells. Since cyclo‐oxygenase metabolites, such as prostaglandin (PG) E2 have been shown to modulate HASM cell growth, we have investigated any autocrine action of endogenously released cyclo‐oxygenase‐1/2 products on the proliferative responses in these cells.
HASM cells were cultured from healthy tissue obtained at lung or heart/lung transplantation. HASM cell proliferation was measured by [3H]‐methyl thymidine uptake by cells and by cell counts. Cyclo‐oxygenase‐2 expression was measured by Western blot analysis and activity measured by the release of PGE2, by radioimmunoasay.
HASM cells proliferated in response to foetal calf serum, a response that was greatly inhibited when cyclo‐oxygenase‐2 was induced with either interleukin‐1β plus tumour necrosis factor‐α or interleukin‐1β, tumour necrosis factorα plus interferonγ (each at 10 ng ml−1). The inhibitory effect of cytokines on HASM cell proliferation was reversed in a concentration dependent manner by either the mixed cyclo‐oxygenase‐1/‐2 inhibitor, indomethacin or the selective cyclo‐oxygenase‐2 inhibitor, L‐745,337 (each at 10 μM).
PGE2 or the stable analogue of prostacyclin, cicaprost concentration‐dependently (0.1 pmol to 1 μM) inhibited serum induced proliferation of HASM cells. By contrast, the TP receptor agonist, U46619 stimulated proliferation of HASM cells when cells were cultured without but not with serum. Other cyclo‐oxygenase products, PGD2, PGF2α had no effect on cellular proliferation at concentrations up to 1 μM.
These observations illustrate a profound inhibitory effect of cyclo‐oxygenase‐2 induction on HASM cell proliferation, possibly via IP or EP receptor activation. Cyclo‐oxygenase‐2 induction has, thus far, been associated with the pro‐inflammatory responses of plasma exudation and oedema formation and is assumed to be an enzyme worthy of selective inhibition in many disease states. However, our observations suggest that cyclo‐oxygenase‐2 can have an anti‐inflammatory, anti‐proliferative function in the airways. These observations may have importance in the use and development of therapies for airway disease such as asthma.

British Journal of Pharmacology (1998) 125, 1102–1108; doi:10.1038/sj.bjp.0702104
Mg2+ and ATP dependence of KATP channel modulator binding to the recombinant sulphonylurea receptor, SUR2B
Authors: Hambrock Annette , Löffler‐Walz Cornelia , Kurachi Yoshihisa , Quast Ulrich 
Published: January 2005

The binding of modulators of the ATP‐sensitive K+ channel (KATP channel) to the murine sulphonylurea receptor, SUR2B, was investigated. SUR2B, a proposed subunit of the vascular KATP channel, was expressed in HEK 293 cells and binding assays were performed in membranes at 37°C using the tritiated KATP channel opener, [3H]‐P1075.
Binding of [3H]‐P1075 required the presence of Mg2+ and ATP. MgATP activated binding with EC50 values of 10 and 3 μM at free Mg2+ concentrations of 3 μM and 1 mM, respectively. At 1 mM Mg2+, binding was lower than at 3 μM Mg2+.
[3H]‐P1075 saturation binding experiments, performed at 3 mM ATP and free Mg2+ concentrations of 3 μM and 1 mM, gave KD values of 1.8 and 3.4 nM and BMAX values of 876 and 698 fmol mg−1, respectively.
In competition experiments, openers inhibited [3H]‐P1075 binding with potencies similar to those determined in rings of rat aorta.
Glibenclamide inhibited [3H]‐P1075 binding with Ki values of 0.35 and 2.4 μM at 3 μM and 1 mM free Mg2+, respectively. Glibenclamide enhanced the dissociation of the [3H]‐P1075‐SUR2B complex suggesting a negative allosteric coupling between the binding sites for P1075 and the sulphonylureas.
It is concluded that an MgATP site on SUR2B with μM affinity must be occupied to allow opener binding whereas Mg2+ concentrations 10 μM decrease the affinities for openers and glibenclamide. The properties of the [3H]‐P1075 site strongly suggest that SUR2B represents the drug receptor of the openers in vascular smooth muscle.

British Journal of Pharmacology (1998) 125, 577–583; doi:10.1038/sj.bjp.0702109
Mechanism of block by tedisamil of transient outward current in human ventricular subepicardial myocytes
Authors: Wettwer Erich , Himmel Herbert M , Amos Gregory J , Li Qi , Metzger Franz , Ravens Ursula 
Published: January 2005

Tedisamil is a new antiarrhythmic drug with predominant class III action. The aim of the present study was to investigate the blocking pattern of the compound on the transient outward current (Ito) in human subepicardial myocytes isolated from explanted left ventricles. Using the single electrode whole cell voltage clamp technique, Ito was analysed after appropriate voltage inactivation of sodium current and block of calcium current.
Tedisamil reduced the amplitude of peak Ito, but did not affect the amplitude of non‐inactivating outward current. The drug accelerated the apparent rate of Ito inactivation. The reduction in time constant of Ito inactivation depended on drug concentration, the apparent IC50 value was 4.4 μM.
Tedisamil affected Ito amplitude in a use‐dependent manner. After 2 min at −80 mV, maximum block of Ito was reached after 4–5 clamp steps either at the frequency of 0.2 or 2 Hz, indicating that the block was not frequency‐dependent in an experimentally relevant range. Recovery from block was very slow and proceeded with a time constant of 12.1±1.8 s. Also in the presence of drug, a fraction of channels recovered from inactivation with a similar time constant as in control myocytes (i.e. 81±40 ms and 51±8 ms, respectively, n.s.).
From the onset of fractional block of Ito by tedisamil during the initial 60 ms of a clamp step, we calculated k1=9×106 mol−1 s−1 for the association rate constant, and k2=23 s−1 for the dissociation rate constant. The resulting apparent KD was 2.6 μM and is similar to the IC50 value.
The effects of tedisamil on Ito could be simulated by assuming a four state channel model where the drug binds to the channel in an open (activated) conformation. It is concluded that in human subepicardial myocytes tedisamil is an open channel blocker of Ito and that this effect probably contributes to the antiarrhythmic potential of this drug.

British Journal of Pharmacology (1998) 125, 659–666; doi:10.1038/sj.bjp.0702110
Disruption of synchronous gamma oscillations in the rat hippocampal slice: A common mechanism of anaesthetic drug action
Authors: Faulkner H J , Traub R D , Whittington M A 
Published: January 2005

At the molecular level much progress has been made towards elucidating the mechanisms of action of general and dissociative anaesthetics. However, little is known about how these molecular actions may lead to disruption of cognitive function.
A promising physiological correlate of cognitive function is the ability of spatially separate areas of the brain to synchronize firing patterns via mutual inhibitory, gamma‐frequency (20–80 Hz) electrical oscillations. Here we examine the effects of five different anaesthetic/hypnotic agents with different primary mechanisms of action on these oscillations in the hippocampus.
Gamma oscillations were elicited simultaneously at two sites at either end of area CA1 by tetanic stimulation. Such oscillations are synchronous between these areas even when separated by up to c. 4 mm in control conditions.
Agents which act directly on GABAA receptor‐mediated inhibition had different effects on synchronous gamma oscillations. Thiopental (10–200 μm) markedly disrupted the oscillation and resulting synchrony whereas the benzodiazepines diazepam and temazepam (0.05–1.0 μM) had little effect.
The opiate morphine (10–200 μM) and dissociative agent ketamine (10–100 μM) had a different profile of effects on gamma oscillations. However, as with thiopental, both agents markedly disrupted between site synchrony. These three agents demonstrated this effect at aqueous concentrations relevant to anaesthetic ED50.
Using the hippocampus as a model neuronal network we propose that, despite differing primary mechanisms of action, anaesthetics may disrupt cognitive function by interfering with the mechanism of generation of synchronous firing patterns between spatially separate areas of the brain.

British Journal of Pharmacology (1998) 125, 483–492; doi:10.1038/sj.bjp.0702113
Analysis of the influence of nucleotidases on the apparent activity of exogenous ATP and ADP at P2Y1 receptors
Authors: Vigne Paul , Philippe Breittmayer Jean , Frelin Christian 
Published: January 2005

ADP is a potent agonist of rat and human P2Y1 purinoceptors. ATP is a weak competitive antagonist. This study analyses the situation in which P2Y1 receptors are exposed to ATP in the presence of exogenous ecto‐nucleotidases (apyrases) that have high or low ATPase/ADPase activity ratio.
Rat brain capillary endothelial cells of the B10 clone express P2Y1 receptors that couple to intracellular Ca2+ mobilization. They have low endogenous ecto‐ATPase and ecto‐ADPase activities.
ATP did not raise intracellular Ca2+ in B10 cells. Addition of apyrases III or VII (1 u ml−1) to ATP treated cells induced large intracellular Ca2+ transients. Apyrases had no action in the absence of ATP.
A 1 u ml−1 apyrase III solution generated 20 μM ADP from 0.1 mM ATP within 15 s. This concentration of ADP was sufficient to produce maximal activation of P2Y1 receptors.
ATP was a full agonist of P2Y1 receptors in the presence of 1 u ml−1 apyrase III. Dose response curves for the apparent actions of ATP were bell shaped in the presence of 0.1 u ml−1 apyrase III. Apyrase III did not alter ADP dose response curves when coincubated with ADP for 15 s.
Apyrase VII (1 u ml−1) shifted dose response curves for the actions of ADP to larger concentrations. It induced a bell shaped ATP dose response curve.
Results suggest that ATPDases prevent P2Y1 receptor activation by degrading ADP but may contribute to P2Y1 receptor activation by generating ADP from ATP.

British Journal of Pharmacology (1998) 125, 675–680; doi:10.1038/sj.bjp.0702115
Recovery by ascorbate of impaired nitric oxide‐dependent relaxation resulting from oxidant stress in rat aorta
Authors: Dudgeon Sinead , Benson David P , MacKenzie Andrew , Paisley‐Zyszkiewicz Karen , Martin William 
Published: January 2005

In this study we investigated the ability of ascorbate to protect nitric oxide from destruction by superoxide anion.
Ascorbate produced concentration‐dependent relaxation of rings of rat aorta, comprising two components: the first, seen at 1–300 μM, reached a maximum of 45.3±2.8%, and was abolished by endothelial removal or treatment with L‐NAME (100 μM), demonstrating involvement of nitric oxide. The second occurred at concentrations of 1 mM and above and was associated with falls in the pH of the bathing fluid.
Pretreatment with ascorbate at concentrations up to 3 mM had no effect on the relaxation to acetylcholine (10 nM–10 μM) on endothelium‐containing rings or adenosine (0.1 μM–3 mM) on endothelium‐denuded rings.
An oxidant stress was applied to aortic rings, comprising inhibition of endogenous Cu/Zn superoxide dismutase by diethyldithiocarbamate (0.1 mM) followed by generation of superoxide anion by hypoxanthine (0.1 mM/xanthine oxidase (16 u ml−1). This reduced maximal acetylcholine‐induced relaxation from 96.7±1.3% to 42.4±3.5% (P<0.001). Treatment with ascorbate (30 μM–3 mM) reversed this blockade in a concentration‐dependent manner.
Our findings show that ascorbate has the ability to protect nitric oxide from destruction by superoxide anion. This action is seen with ascorbate at levels normally present in plasma, suggesting that this antioxidant may exert a tonic protective effect on nitric oxide within the vasculature.

British Journal of Pharmacology (1998) 125, 782–786; doi:10.1038/sj.bjp.0702120
Decline in the expression of copper/zinc superoxide dismutase in the kidney of rats with endotoxic shock: Effects of the superoxide anion radical scavenger, tempol, on organ injury
Authors: Leach Mary , Frank Stefan , Olbrich Antje , Pfeilschifter Josef , Thiemermann Christoph 
Published: January 2005

Endotoxaemia causes an enhanced formation of reactive oxygen species (ROS) which contribute to the multiple organ dysfunction syndrome (MODS) in septic shock. Here we investigate (i) the effects of endotoxin on the expression of two isoforms of superoxide dismutase (SOD), namely Cu/Zn‐SOD (cytosol) and Mn‐SOD (mitochondria) in the rat kidney, and (ii) the effects of the radical scavenger tempol on the MODS caused by lipopolysaccharide (LPS, E. coli, 6 mg kg−1 i.v.) in the rat.
Endotoxaemia resulted in a rapid, but transient, decline in the expression of both mRNA and protein of Cu/Zn‐SOD as well as an increase in the expression of the mRNA of Mn‐SOD in the kidney. Endotoxaemia for 6 h also caused hypotension, acute renal dysfunction, hepatocellular injury, pancreatic injury and an increase in the plasma levels of nitrite/nitrate.
Pretreatment of rats with tempol (100 mg kg−1 i.v. bolus injection, 15 min prior to LPS followed by an infusion of 30 mg kg−1 i.v., n=9) did not affect the circulatory failure, but attenuated the renal dysfunction and the hepatocellular injury/dysfunction caused by LPS. Tempol did not affect the rise in nitrite/nitrate caused by endotoxin.
These results imply that an enhanced formation of ROS (including superoxide anions) in conjunction with inadequate defences against such ROS contributes to the injury and dysfunction of the kidney and the liver in endotoxic shock.

British Journal of Pharmacology (1998) 125, 817–825; doi:10.1038/sj.bjp.0702123
Effect of DMPPO, a phosphodiesterase type 5 inhibitor, on hypoxic pulmonary hypertension in rats
Authors: Eddahibi Saadia , Raffestin Bernadette , Le Monnier de Gouville Anne‐Charlotte , Adnot Serge 
Published: January 2005

Cyclic guanosine 3′–5′‐monophosphate (cyclic GMP) is the second messenger of important physiologically active mediators controlling the pulmonary vascular tone. To potentiate the effects of cyclic GMP on the pulmonary vasculature, we used DMPPO, a new selective PDE‐5 inhibitor, and examined its action in a rat model of hypoxic pulmonary hypertension.
Levels of cyclic GMP measured during baseline conditions at 5 and 60 min of perfusion were similar in the perfusate of isolated lungs from normoxic and chronically hypoxic rats and did not differ with time. Pretreatment with DMPPO (1 μM) induced a larger increase in cyclic GMP concentration in the perfusate from chronically hypoxic rat lungs (319±36 at 5 min to 1821±83 pmol ml−1 at 60 min) than in normoxic rat lungs (329±20 to 1281±127 pmol ml−1, P<0.05).
In isolated lungs preconstricted with U‐46619, pretreatment with DMPPO (1 μM) potentiated the vasodilator effects of atrial natriuretic peptide (100 pM–10 nM) and sodium nitroprusside (1 pM–10 nM), but did not alter vasodilation to isoproterenol.
In conscious rats previously exposed to 15 days hypoxia and studied under 10% O2, DMPPO (0.01, 0.05 and 0.1 mg kg−1, i.v. bolus) caused a dose‐dependent decrease in pulmonary arterial pressure (Pap) with no change in systemic artery pressure (Sap) and cardiac output.
Continuous infusion of DMPPO (0.1 mg kg−1 h−1 i.v. by osmotic pumps) in rats exposed to 10% O2 during 2‐weeks reduced the Pap (P<0.05) and the degree of muscularization of pulmonary vessels at the alveolar wall (P<0.01) and alveolar duct levels (P<0.05) despite no significant change in right ventricular hypertrophy.
These results suggest that cyclic GMP phosphodiesterase inhibition may selectively dilate pulmonary circulation during chronic hypoxia.

British Journal of Pharmacology (1998) 125, 681–688; doi:10.1038/sj.bjp.0702124