bluuebunny/crossref_metadata_2025_split huggingface dataset:
Attenuation of cardiac fibrosis by pirfenidone and amiloride in DOCA‐salt hypertensive rats
Authors: Mirkovic Stevo , Seymour Anne‐Marie L , Fenning Andrew , Strachan Anna , Margolin Solomon B , Taylor Stephen M , Brown Lindsay 
Published: January 2005

This study has administered pirfenidone (5‐methyl‐1‐phenyl‐2‐[1H]‐pyridone) or amiloride to attenuate the remodelling and associated functional changes, especially an increased cardiac stiffness, in DOCA‐salt hypertensive rats.
In control rats, the elimination half‐life of pirfenidone following a single intravenous dose of 200 mg kg−1 was 37 min while oral bioavailability at this dose was 25.7%. Plasma pirfenidone concentrations in control rats averaged 1.9±0.1 μg ml−1 over 24 h after 14 days' administration as a 0.4% mixture in food.
Pirfenidone (approximately 250 – 300 mg kg−1 day−1 as 0.4% in food) and amiloride (1 mg kg−1 day−1 sc) were administered for 2 weeks starting 2 weeks post‐surgery. Pirfenidone but not amiloride attenuated ventricular hypertrophy (2.69±0.09, UNX 2.01±0.05. DOCA‐salt 3.11±0.09 mg kg−1 body wt) without lowering systolic blood pressure.
Collagen deposition was significantly increased in the interstitium after 2 weeks and further increased with scarring of the left ventricle after 4 weeks; pirfenidone and amiloride reversed the increases and prevented further increases. This accumulation of collagen was accompanied by an increase in diastolic stiffness constant; both amiloride and pirfenidone reversed this increase.
Noradrenaline potency (positive chronotropy) was decreased in right atria (neg log EC50: control 6.92±0.06; DOCA‐salt 6.64±0.08); pirfenidone but not amiloride reversed this change. Noradrenaline was a more potent vasoconstrictor in thoracic aortic rings (neg log EC50: control 6.91±0.10; DOCA‐salt 7.90±0.07); pirfenidone treatment did not change noradrenaline potency.
Thus, pirfenidone and amiloride reverse and prevent cardiac remodelling and the increased cardiac stiffness without reversing the increased vascular responses to noradrenaline.

British Journal of Pharmacology (2002) 135, 961–968; doi:10.1038/sj.bjp.0704539
Pharmacological characterization of the chemokine receptor, CCR5
Authors: Mueller Anja , Mahmoud Nasir G , Goedecke Marc C , McKeating Jane A , Strange Philip G 
Published: January 2005

We investigated the effects of a number of naturally occurring chemokines (MIP‐1α, MIP‐1β, RANTES, MCP‐2, MCP‐3, MCP‐4) on different processes linked to the chemokine receptor CCR5 in recombinant CHO cells expressing the receptor at different levels.
Internalization of CCR5 following chemokine treatment was studied and MIP‐1α, MIP‐1β and RANTES (50 nM) were able to induce internalization (∼50%) of the receptor. Internalization due to MCP‐2, MCP‐3 and MCP‐4 was less (∼20%).
Phosphorylation of CCR5 following chemokine treatment was studied and MIP‐1α, MIP‐1β and RANTES (50 nM) were able to induce phosphorylation of CCR5 whereas the other chemokines did not induce CCR5 phosphorylation.
MIP‐1α, MIP‐1β, RANTES and MCP‐2 were able to stimulate [35S]‐GTPγS binding, an index of receptor/G protein activation, whereas MCP‐3 and MCP‐4 had no effect in this assay. MCP‐2 was a partial agonist (∼80%) compared to MIP‐1α, MIP‐1β and RANTES, which gave similar maximal stimulations in this assay.
MIP‐1α, MIP‐1β, RANTES, MCP‐2 and MCP‐4 were able to stimulate increases in intracellular calcium ions via activation of CCR5 whereas MCP‐3 was without effect.
It is concluded that different chemokines interacting with CCR5 mediate different patterns of cellular responses.

British Journal of Pharmacology (2001) 135, 1033–1043; doi:10.1038/sj.bjp.0704540
Divergent effects of vitamin C on relaxations of rabbit aortic rings to acetylcholine and NO‐donors
Authors: Saram K de , McNeill K L , Khokher S , Ritter J M , Chowienczyk P J 
Published: January 2005

Vitamin C may influence NO‐dependent relaxation independently of effects on oxidant stress.
We investigated effects of vitamin C (0.1 – 10 mmol l−1) on relaxation of pre‐constricted rabbit aortic rings to acetylcholine (ACh), authentic NO and the NO‐donors glyceryl trinitrate (GTN), nitroprusside (NP) and S‐nitroso‐N‐acetyl‐penicillamine (SNAP). DETCA (2 – 6 mmol l−1), a cell permeable inhibitor of endogenous Cu‐Zn superoxide dismutase (SOD) was used to increase intracellular superoxide anion (O2−).
Vitamin C reduced the response to ACh (71±7% inhibition of maximum relaxation at 10 mmol l−1) and inhibited relaxation to authentic NO. Vitamin C inhibited relaxation to GTN but potentiated relaxations to NP and SNAP, causing a parallel shift to a lower concentration range of the log dose‐response curve by approximately one log unit at the highest dose.
Vitamin C increased the concentration of NO in bath solution (plus EDTA, 1.0 mmol l−1) following the addition of SNAP from 53±14 to 771±101 nmol l−1 over the range 0.1 – 3.0 mmol l−1.
DETCA inhibited relaxation to ACh (71±9% inhibition of maximum relaxation). This inhibition was abolished by a cell permeable SOD mimetic, but not by vitamin C. DETCA inhibited relaxation to SNAP but not that to NP nor to GTN.
Vitamin C inhibits endothelium‐dependent relaxations of rabbit aortic rings to ACh and authentic NO and does not reverse impaired relaxation resulting from increased intracellular oxidant stress. Vitamin C potentiates relaxation to the NO‐donors NP and SNAP by a mechanism that could involve release of NO from nitrosothiols.

British Journal of Pharmacology (2002) 135, 1044–1050; doi:10.1038/sj.bjp.0704541
Specific [3H]‐guanosine binding sites in rat brain membranes
Authors: Traversa Ugo , Bombi Giulia , Iorio Patrizia Di , Ciccarelli Renata , Werstiuk Eva S , Rathbone Michel P 
Published: January 2005

Extracellular guanosine has diverse effects on many cellular components of the central nervous system, some of which may be related to its uptake into cells and others to its ability to release adenine‐based purines from cells. Yet other effects of extracellular guanosine are compatible with an action on G‐protein linked cell membrane receptors.Specific binding sites for [3H]‐guanosine were detected on membrane preparations from rat brain. The kinetics of [3H]‐guanosine binding to membranes was described by rate constants of association and dissociation of 2.6122×107 M−1 min−1and 1.69 min−1, respectively.A single high affinity binding site for [3H]‐guanosine with aKDof 95.4±11.9 nMand Bmaxof 0.57±0.03 pmol mg−1protein was shown.This site was specific for guanosine, and the order of potency in displacing 50 nM[3H]‐guanosine was: guanosine=6‐thio‐guanosine>inosine>6‐thio‐guanine>guanine. Other naturally occurring purines, such as adenosine, hypoxanthine, xanthine caffeine, theophylline, GDP, GMP and ATP were unable to significantly displace the radiolabelled guanosine. Thus, this binding site is distinct from the well‐characterized receptors for adenosine and purines.The addition of GTP produced a small concentration‐dependent decrease in guanosine binding, suggesting this guanosine binding site was linked to a G‐protein.Our results therefore are consistent with the existence of a novel cell membrane receptor site, specific for guanosine.British Journal of Pharmacology(2002)135, 969–976; doi:10.1038/sj.bjp.0704542
Cyclosporin A‐induced free radical generation is not mediated by cytochrome P‐450
Authors: Krauskopf Alexandra , Buetler Timo M , Nguyen Nathalie S D , Macé Katherine , Ruegg Urs T 
Published: January 2005

Reactive oxygen species (ROS) have been proposed to play a role in the side effects of the immunosuppressive drug cyclosporin A (CsA).
The aim of this study was to investigate whether cytochrome P‐450 (CYP) dependent metabolism of CsA could be responsible for ROS generation since it has been suggested that CsA may influence the CYP system to produce ROS.
We show that CsA (1 – 10 μM) generated antioxidant‐inhibitable ROS in rat aortic smooth muscle cells (RASMC) using the fluorescent probe 2,7‐dichlorofluorescin diacetate.
Using cytochrome c as substrate, we show that CsA (10 μM) did not inhibit NADPH cytochrome P‐450 reductase in microsomes prepared from rat liver, kidney or RASMC.
CsA (10 μM) did not uncouple the electron flow from NADPH via NADPH cytochrome P‐450 reductase to the CYP enzymes because CsA did not inhibit the metabolism of substrates selective for several CYP enzymes that do not metabolize CsA in rat liver microsomes.
CsA (10 μM) did not generate more radicals in CYP 3A4 expressing immortalized human liver epithelial cells (T5‐3A4 cells) than in control cells that do not express CYP 3A4.
Neither diphenylene iodonium nor the CYP 3A inhibitor ketoconazole were able to block ROS formation in rat aortic smooth muscle or T5‐3A4 cells.
These results demonstrate that CYP enzymes do not contribute to CsA‐induced ROS formation and that CsA neither inhibits NADPH cytochrome P‐450 reductase nor the electron transfer to the CYP enzymes.

British Journal of Pharmacology (2002) 135, 977–986; doi:10.1038/sj.bjp.0704544
Prevention of a hypoxic Ca2+i response by SERCA inhibitors in cerebral arterioles
Authors: Guibert C , Flemming R , Beech D J 
Published: January 2005

The aim of the study was to investigate the mechanism of a novel effect of hypoxia on intracellular Ca2+ signalling in rabbit cerebral arteriolar smooth muscle cells, an effect that was resistant to the L‐type Ca2+ channel antagonist methoxyverapamil (D600).
[Ca2+]i of smooth muscle cells in intact arteriolar fragments was measured using the Ca2+‐indicator dye fura‐PE3. Hypoxia (PO2 10 – 20 mmHg) lowered basal [Ca2+]i but did not inhibit Ca2+ entry pathways measured by Mn2+‐quenching of fura‐PE3.
The effect of hypoxia was completely prevented by thapsigargin or cyclopiazonic acid, selective inhibitors of sarcoplasmic reticulum Ca2+ ATPase (SERCA). Since these inhibitors do not block Ca2+ extrusion or uptake via the plasma membrane, the data indicate that the effect of hypoxia depends on a functional sarcoplasmic reticulum.
Because actions of nitric oxide (NO) on vascular smooth muscle are also prevented by SERCA inhibitors it was explored whether the effect of hypoxia occurred via modulation of endogenous NO release. Residual NOS‐I and NOS‐III were detected by immunostaining, and there were NO‐dependent effects of NOS inhibitors on Ca2+i‐signalling. Nevertheless, inhibition of endogenous NO production did not prevent the effect of hypoxia on [Ca2+]i.
The experiments reveal a novel nitric oxide‐independent effect of hypoxia that is prevented by SERCA inhibitors.

British Journal of Pharmacology (2002) 135, 927–934; doi:10.1038/sj.bjp.0704547
The 5‐series F2‐isoprostanes possess no vasomotor effects in the rat thoracic aorta, the human internal mammary artery and the human saphenous vein
Authors: Marlière Stéphanie , Cracowski Jean‐Luc , Durand Thierry , Chavanon Olivier , Bessard Janine , Guy Alexandre , Stanke‐Labesque Françoise , Rossi Jean‐Claude , Bessard Germain 
Published: January 2005

Among the F2‐isoprostanes, the 15‐ and the 5‐series are currently used as markers of lipid peroxidation in vascular diseases. 15‐F2t‐IsoP (also named iPF2α‐III) exerts a vasoconstriction in most vessels, whereas no data is available concerning 5‐F2t‐IsoP (also named iPF2α‐VI), which is more abundant in plasma.
The aim of this study was to determine whether 5‐F2t‐IsoP possess any vascular effects on various vessels including the isolated rat thoracic aorta, the human internal mammary artery and the saphenous vein.
In organ baths, 5‐F2t‐IsoP and its 5‐epimer did not affect the basal tone of any vessel, unlike 15‐F2t‐IsoP. These compounds possessed no antagonist effects on 15‐F2t‐IsoP‐induced contractions, No dilator effect was observed in comparison with sodium nitroprusside and acetylcholine on the rat aorta.
In conclusion, we show that unlike 15‐F2t‐IsoP, 5‐F2t‐IsoP and its 5‐epimer possess no vasomotor effects and as such are unlikely to be involved in the pathogenesis of vascular diseases. Further studies are required to test whether these mediators may have effects on systems not being measured in the current study.

British Journal of Pharmacology (2002) 135, 1276–1280; doi:10.1038/sj.bjp.0704558
Mechanisms of action of proteinase‐activated receptor agonists on human platelets
Authors: Chung Ada W Y , Jurasz Paul , Hollenberg Morley D , Radomski Marek W 
Published: January 2005

We studied the activation of human platelets by thrombin and proteinase activated receptor (PAR)‐activating peptides (PAR‐APs) [SFLLRNPNDKYEPF‐amide (TRAP), TFLLR‐amide (PAR1AP) and AYPGKF‐amide (PAR4AP)].
PAR agonist‐induced platelet aggregation, glycoprotein (GP) Ib and GPIIb/IIIa surface expression and ADP release were measured by light aggregometry, flow cytometry and chemiluminescence.
Aggregation inhibitors, including prostacyclin (PGI2), nitric oxide‐releasing agent (S‐nitroso‐glutathione, GSNO), aspirin, apyrase, and phenanthroline were used to study the susceptibility of PAR agonist‐induced aggregation to pharmacological inhibition.
Thrombin was the most potent platelet agonist, followed by PAR1AP, TRAP and PAR4AP.
The aggregatory potencies of PAR‐APs were not modified by the aminopeptidase inhibitor, amastatin.
Subthreshold concentrations of PAR1AP potentiated the effects of PAR4AP to stimulate maximal aggregation.
Both PGI2 and GSNO reduced PAR agonist‐induced aggregation and diminished GPIIb/IIIa up‐regulation.
PAR agonist‐induced aggregation was aspirin‐insensitive indicating a minor role for TXA2.
In contrast, phenanthroline and apyrase significantly enhanced the anti‐aggregatory effects of aspirin against thrombin‐, PAR1AP‐ and TRAP‐induced aggregation suggesting the involvement of ADP‐ and MMP‐2‐dependent pathways.
PAR4AP‐induced aggregation (but not PAR1AP‐induced aggregation) was entirely ADP‐dependent (abolished by apyrase) and resistant to phenanthroline (MMP‐2‐independent).
Thus, the mechanisms of PAR1 and 4‐induced platelet aggregation are distinct and depend differentially on their ability to interact with pathways of aggregation, along with the subsequent activation of GPIIb/IIIa receptors.

British Journal of Pharmacology (2002) 135, 1123–1132; doi:10.1038/sj.bjp.0704559
Multiple pathways for fluoroquinolone secretion by human intestinal epithelial (Caco‐2) cells
Authors: Lowes Simon , Simmons Nicholas L 
Published: January 2005

Human intestinal epithelial Caco‐2 cells, T84 cells, and MDCKII cells transfected with human MDR1, were used to investigate the mechanistic basis of transintestinal fluoroquinolone secretion.
The fluoroquinolone grepafloxacin was secreted across Caco‐2 monolayers by a saturable process (Vmax=16.9±3.4 nmol.cm−2.h−1). Net secretion was reduced by 2‐deoxyglucose/azide treatment to reduce intracellular ATP.
Grepafloxacin inhibited [14C]‐ciprofloxacin (100 μM) secretion across Caco‐2 monolayers (K0.5=0.8 mM), and concurrently increased the cellular accumulation of ciprofloxacin from the basal medium, indicating inhibition of export across the apical membrane.
The unconjugated bile acid, cholic acid, was secreted across Caco‐2 monolayers, and this secretion was sensitive to inhibition by the MRP‐selective inhibitor MK‐571, suggesting MRP2 involvement. Secretion of cholic acid (10 μM) across the apical membrane was also inhibited by grepafloxacin (K0.5=0.3 mM), but not by ciprofloxacin.
In MDCKII‐MDR1 monolayers, net secretion of grepafloxacin was increased by 3.5 fold compared with untransfected controls. Neither ciprofloxacin nor cholic acid showed net secretion in either MDCKII or MDCKII‐MDR1 monolayers, showing that in contrast to grepafloxacin, neither are substrates for MDR1.
In T84 monolayers, which express MDR1 but not MRP2, neither ciprofloxacin nor cholic acid was secreted, whilst the Vmax for grepafloxacin secretion was lower than in Caco‐2 cells, which express both MDR1 and MRP2.
In conclusion, the transepithelial secretion of grepafloxacin is mediated by both MRP2 and MDR1, whereas ciprofloxacin is a substrate for neither. Grepafloxacin also competes for the ciprofloxacin‐sensitive pathway, which remains to be elucidated.

British Journal of Pharmacology (2002) 135, 1263–1275; doi:10.1038/sj.bjp.0704560
Extracellular signal‐regulated kinase plays an essential role in endothelin‐1‐induced homotypic adhesion of human neutrophil granulocytes
Authors: József Levente , Khreiss Tarek , Fournier Alain , Chan John S D , Filep János G 
Published: January 2005

Endothelin‐1 (ET‐1) stimulates integrin‐dependent adhesion of neutrophil granulocytes to endothelial cells, one of the early key events in acute inflammation. However, the signalling pathway(s) of ET‐1‐stimulated neutrophil adhesive responses has not been elucidated. Previous studies indicated that extracellular signal‐regulated kinase (ERK) activation could mediate rapid responses of neutrophil granulocytes to various stimuli. In this study, we investigated the role of ERK signalling in human neutrophil granulocytes challenged with ET‐1.
ET‐1 rapidly down‐regulated the expression of L‐selectin and up‐regulated the expression of CD11b/CD18 on the neutrophil surface. Concomitantly, ET‐1 induced homotypic adhesion (aggregation) of neutrophils, that was blocked by a monoclonal antibody to CD18.
ET‐1, through ETA receptors, evoked activation of Ras and subsequent phosphorylation of Raf‐1, mitogen‐activated protein kinase kinase (MAPK/ERK kinase) and ERK 1/2. ERK activation by ET‐1 was rapid, concordant with the kinetics of ET‐1‐stimulated neutrophil aggregation.
Neutrophil responses to ET‐1 were markedly attenuated by the MAPK/ERK kinase inhibitor PD98059, whereas inhibitors of p38 MAPK, tyrosine kinases and phosphatidylinositol 3‐kinase had no detectable effects. We have observed a tight correlation between neutrophil ERK activation and homotypic adhesion.
These data indicate an essential role for ERK in mediating ET‐1‐stimulated adhesive responses of human neutrophil granulocytes.

British Journal of Pharmacology (2002) 135, 1167–1174; doi:10.1038/sj.bjp.0704561
Protease‐activated receptor‐2 (PAR‐2) in the rat gastric mucosa: immunolocalization and facilitation of pepsin/pepsinogen secretion
Authors: Kawao Naoyuki , Sakaguchi Yuriko , Tagome Ai , Kuroda Ryotaro , Nishida Shozo , Irimajiri Kiyohiro , Nishikawa Hiroyuki , Kawai Kenzo , Hollenberg Morley D , Kawabata Atsufumi 
Published: January 2005

Agonists of protease‐activated receptor‐2 (PAR‐2) trigger neurally mediated mucus secretion accompanied by mucosal cytoprotection in the stomach. The present study immunolocalized PAR‐2 in the rat gastric mucosa and examined if PAR‐2 could modulate pepsin/pepsinogen secretion in rats.
PAR‐2‐like immunoreactivity was abundant in the deep regions of gastric mucosa, especially in chief cells.
The PAR‐2 agonist SLIGRL‐NH2, but not the control peptide LSIGRL‐NH2, administered i.v. repeatedly at 0.3 – 1 μmol kg−1, four times in total, significantly facilitated gastric pepsin secretion, although a single dose produced no significant effect.
The PAR‐2‐mediated gastric pepsin secretion was resistant to omeprazole, NG‐nitro‐L‐arginine methyl ester (L‐NAME) or atropine, and also to ablation of sensory neurons by capsaicin.
Our study thus provides novel evidence that PAR‐2 is localized in mucosal chief cells and facilitates gastric pepsin secretion in the rats, most probably by a direct mechanism.

British Journal of Pharmacology (2002) 135, 1292–1296; doi:10.1038/sj.bjp.0704562
Probucol preserves endothelial function by reduction of the endogenous nitric oxide synthase inhibitor level
Authors: Jiang Jun‐Lin , Li Nian‐sheng , Li Yuan‐Jian , Deng Han‐Wu 
Published: January 2005

Oxide low‐density lipoprotein (ox‐LDL) is believed to play an important role in early events of atherogenesis, and asymmetric dimethylarginine (ADMA) is associated with the development of endothelial dysfunction. The present study examined the effect of a single injection of native low‐density lipoprotein (LDL) on endothelium function and the serum level of ADMA and the effect of probucol on endothelium function and ADMA level in rats.
Endothelial injury was induced by intravenous injection of LDL at the dose of 2, 4, or 6 mg kg−1 for 24, 48, or 72 h, and vasodilator responses to acetylcholine in the aortic rings and serum levels of ADMA, nitrite/nitrate (NO) and malondialdehyde (MDA) were determined.
Pretreatment with LDL markedly reduced endothelium‐dependent relaxation in a concentration‐dependent manner. Inhibition of vasodilator responses to acetylcholine by LDL was abolished in the presence of L‐arginine (3×10−4 M). Serum levels of ADMA and MDA were significantly elevated in the rats pretreated with LDL, while serum level of nitrite/nitrate was markedly decreased.
Pretreatment with probucol significantly improved endothelium‐dependent relaxation, decreased concentrations of ADMA and MDA and increased nitrite/nitrate level in the rats treated with LDL. A similar effect was seen in the rats pretreated with an antioxidant vitamin E.
These results suggest that a single injection of native LDL causes endothelial dysfunction by elevation of ADMA levels and that the protective effect of probucol on endothelial cells is related to reduction of ADMA concentration.

British Journal of Pharmacology (2002) 135, 1175–1182; doi:10.1038/sj.bjp.0704563
Platelet‐activating factor drives eotaxin production in an allergic pleurisy in mice
Authors: Klein André , Pinho Vanessa , Alessandrini Ana Letícia , Shimizu Takao , Ishii Satoshi , Teixeira Mauro M 
Published: January 2005

The activation of eosinophils via G‐protein‐coupled seven transmembran receptors play a necessary role in the recruitment of these cells into tissue. The present study investigates a role for PAF in driving eotaxin production and eosinophil recruitment in an allergic pleurisy model in mice.
The intrapleural injection of increasing doses of PAF (10−11 to 10−9 moles per cavity) induced a dose‐ and PAF receptor‐dependent recruitment of eosinophils 48 h after stimulation.
Intrapleural injection of PAF induced the rapid (within 1 h) release of eotaxin into the pleural cavity of mice and an anti‐eotaxin antibody effectively inhibited PAF‐induced recruitment of eosinophils.
Eosinophil recruitment in the allergic pleurisy was markedly inhibited by the PAF receptor antagonist UK‐74,505 (modipafant, 1 mg kg−1). Moreover, recruitment of eosinophils in sensitized and challenged PAF receptor‐deficient animals was lower than that observed in wild‐type animals.
Blockade of PAF receptors with UK‐74,505 suppressed by 85% the release of eotaxin in the allergic pleurisy.
Finally, the injection of a sub‐threshold dose of PAF and eotaxin cooperated to induce eosinophil recruitment in vivo.
In conclusion, the production of PAF in an allergic reaction could function in multiple ways to facilitate the recruitment of eosinophils  –  by facilitating eotaxin release and by cooperating with eotaxin to induce greater recruitment of eosinophils.

British Journal of Pharmacology (2002) 135, 1213–1218; doi:10.1038/sj.bjp.0704570