bluuebunny/crossref_metadata_2025_split huggingface dataset:
Veratridine induces apoptotic death in bovine chromaffin cells through superoxide production
Authors: Jordán Joaquín , Galindo María F , Calvo Soledad , González‐García Carmen , Ceña Valentín 
Published: January 2005

The molecular mechanisms involved in veratridine‐induced chromaffin cell death have been explored.
We have found that exposure to veratridine (30 μM, 1 h) produces a delayed cellular death that reaches 55% of the cells 24 h after veratridine exposure. This death has the features of apoptosis as DNA fragmentation can be observed.
Calcium ions play an important role in veratridine‐induced chromaffin cell death because the cell permeant Ca2+ chelator BAPTA‐AM and extracellular Ca2+ removal completely prevented veratridine‐induced toxicity.
Following veratridine treatment, there is a decrease in mitochondrial function and an increase in superoxide anion production. Veratridine‐induced increase in superoxide production was blocked by tetrodotoxin (TTX; 10 μM), extracellular Ca2+ removal and the mitochondrial permeability transition pore blocker cyclosporine A (10 μM).
Veratridine‐induced death was prevented by different antioxidant treatments including catalase (100 IU ml−1), N‐acetyl cysteine (100 μM), allopurinol (100 μM) or vitamin E (50 μM).
Veratridine‐induced DNA fragmentation was prevented by TTX (10 μM).
Veratridine produced a time‐dependent increase in caspase activity that was prevented by Ca2+ removal and TTX (10 μM). In addition, calpain and caspases inhibitors partially prevented veratridine‐induced death.
These results indicate that chromaffin cells share with neurons the molecular machinery involved in apoptotic death and might be considered a good model to study neuronal death during neurodegeneration.

British Journal of Pharmacology (2000) 130, 1496–1504; doi:10.1038/sj.bjp.0703451
Disparate ligand‐mediated Ca2+ responses by wild‐type, mutant Ser200Ala and Ser204Ala α2A‐adrenoceptor : Gα15 fusion proteins: evidence for multiple ligand‐activation binding sites
Authors: Pauwels P J , Colpaert F C 
Published: January 2005

Ligand : receptor interactions were analysed at wt, mutant Ser200Ala and Ser204Ala α2A ARs by measuring Ca2+ responses in CHO‐K1 cells either by co‐expression with a Gα15 protein or at a receptor : Gα15 protein stoichiometry of 1.0 using fusion proteins.
The magnitude of the UK 14304‐mediated Ca2+ response as elicited by a Gα15 protein was largest with both mutant Ser200Ala and Ser204Ala α2AARs compared to the wt α2A AR in the co‐expression and fusion protein experiments.
The activation profiles of the wt and both mutant α2A ARs as analysed by a series of α2 AR agonists differed. d‐Medetomidine and clonidine appeared most efficacious at the Ser204Ala α2A AR, whereas oxymetazoline was also partially active at the Ser200Ala α2A AR. Talipexole was silent at both mutant α2A ARs. The intrinsic activity of (−)‐adrenaline was either absent or partial at the Ser204Ala and Ser200Ala α2A AR, respectively. This latter observation is related to its lower binding affinity for both mutant α2A ARs.
Ligands characterized as antagonists at wt and Ser200Ala α2A ARs demonstrated either no intrinsic activity (i.e., RX 811059) or positive efficacy with a different rank order of maximal response at the Ser204Ala α2A AR (atipamezole=SKF 86466=idazoxan>dexefaroxan) than Asp79Asn α2A AR (atipamezole>idazoxan≃SKF 86466>dexefaroxan) and Thr373Lys α2A AR (SKF 86466>atipamezole≃idazoxan>dexefaroxan). These effects were only observed in the co‐expression experiments at concentrations in line with their binding affinities.
In conclusion, these Ca2+ data suggest that multiple activation binding sites exist for these ligands at the α2A AR, and that their activation may be affected in different ways by the mutations being investigated.

British Journal of Pharmacology (2000) 130, 1505–1512; doi:10.1038/sj.bjp.0703455
Involvement of interleukin‐1 in the inflammatory actions of aminobisphosphonates in mice
Authors: Yamaguchi Kouji , Motegi Katsutoshi , Iwakura Yoichiro , Endo Yasuo 
Published: January 2005

Aminobisphosphonates (aminoBPs) are potent inhibitors of bone resorption. However, they cause undesirable inflammatory reactions, including fever, in humans. Intraperitoneal injection of aminoBPs into mice also induces inflammatory reactions, including a prolonged elevation of the activity of the histamine‐forming enzyme, histidine decarboxylase (HDC). Because interleukin‐1 (IL‐1) is a typical pyrogen and a strong inducer of HDC, we examined whether aminoBPs induce inflammatory reactions in mice deficient in genes for both IL‐1α and IL‐1β (IL‐1‐KO mice).
In control mice, aminoBPs induced an elevation of HDC activity and other inflammatory reactions (enlargement of the spleen, atrophy of the thymus, exudate in the thorax and increase in granulocytic cells in the peritoneal cavity). These responses were all weak or undetectable in IL‐1‐KO mice.
We have previously shown that lipopolysaccharides (LPSs) from Escherichia coli and Prevotella intermedia (a prevalent gram‐negative bacterium both in periodontitis and endodontal infections) are capable of inducing HDC activity in various tissues in mice. In control mice treated with an aminoBP, the LPS‐induced elevations of serum IL‐1 (α and β) and tissue HDC activity were both markedly augmented. However, such an augmentation of HDC activity was small or undetectable in IL‐1‐KO mice.
These results, taken together with our previous findings (i) suggest that IL‐1 is involved in the aminoBP‐induced inflammatory reactions and (ii) lead us to think that under some conditions, inflammatory reactions induced by gram‐negative bacteria might be augmented in patients treated with an aminoBP.
In this study, we also obtained a result suggesting that IL‐1‐deficiency might be compensated by a second, unidentified, mechanism serving to induce HDC in response to LPS when IL‐1 is lacking.

British Journal of Pharmacology (2000) 130, 1646–1654; doi:10.1038/sj.bjp.0703460
Replacement of the carboxylic acid group of prostaglandin F2α with a hydroxyl or methoxy substituent provides biologically unique compounds
Authors: Woodward D F , Krauss A H‐P , Chen J , Gil D W , Kedzie K M , Protzman C E , Shi L , Chen R , Krauss H A , Bogardus A , Dinh H T T , Wheeler L A , Andrews S W , Burk R M , Gac T , Roof M B , Garst M E , Kaplan L J , Sachs G , Pierce K L , Regan J W , Ross R A , Chan M F 
Published: January 2005

Replacement of the carboxylic acid group of PGF2α with the non‐acidic substituents hydroxyl (‐OH) or methoxy (‐OCH3) resulted in an unexpected activity profile.
Although PGF2α 1‐OH and PGF2α 1‐OCH3 exhibited potent contractile effects similar to 17‐phenyl PGF2α in the cat lung parenchymal preparation, they were approximately 1000 times less potent than 17‐phenyl PGF2α in stimulating recombinant feline and human FP receptors.
In human dermal fibroblasts and Swiss 3T3 cells PGF2α 1‐OH and PGF2α 1‐OCH3 produced no Ca2+ signal until a 1 μM concentration was exceeded. Pretreatment of Swiss 3T3 cells with either 1 μM PGF2α 1‐OH or PGF2α 1‐OCH3 did not attenuate Ca2+ signal responses produced by PGF2α or fluprostenol. In the rat uterus, PGF2α 1‐OH was about two orders of magnitude less potent than 17‐phenyl PGF2α whereas PGF2α 1‐OCH3 produced only a minimal effect.
Radioligand binding studies on cat lung parenchymal plasma membrane preparations suggested that the cat lung parenchyma does not contain a homogeneous population of receptors that equally respond to PGF2α1‐OH, PGF2α1‐OCH3, and classical FP receptor agonists.
Studies on smooth muscle preparations and cells containing DP, EP1, EP2, EP3, EP4, IP, and TP receptors indicated that the activity of PGF2α 1‐OH and PGF2α 1‐OCH3 could not be ascribed to interaction with these receptors.
The potent effects of PGF2α 1‐OH and PGF2α 1‐OCH3 on the cat lung parenchyma are difficult to describe in terms of interaction with the FP or any other known prostanoid receptor.

British Journal of Pharmacology (2000) 130, 1933–1943; doi:10.1038/sj.bjp.0703462
Heart failure development in rats with ascending aortic constriction and angiotensin‐converting enzyme inhibition
Authors: Turcani Marian , Rupp Heinz 
Published: January 2005

It remains unknown whether angiotensin‐converting enzyme (ACE) inhibition can prevent heart failure in rats with a fixed high pressure load of the left ventricle and if this effect could be attributed to normalization of contractile protein phenotype and cardiac collagen content.
Rats with constriction of the ascending aorta were treated with the ACE inhibitor quinapril (6 mg kg−1 day−1) (n=95) or placebo (n=96) (starting 6 weeks post surgery.
Quinapril treatment improved survival markedly (P<0.0000001) during the 24 weeks observation period. There were 69 deaths with placebo and only 25 deaths with quinapril. At the end of the observation period signs of left ventricular backward failure were, however, detected in 75 rats with placebo and in 67 rats treated with quinapril (P=0.229). Cox proportional hazard model with time‐dependent covariates was used to document that the effect of quinapril treatment had been dependent on time. Quinapril had no significant effect on the development of morphological signs of left ventricular dysfunction after the first 54 days of treatment.
The increased isomysin V3 proportion of hypertrophied non‐failing hearts was also not affected by quinapril treatment. Irrespective of treatment, failing hypertrophied hearts were characterized by an increase in left ventricular volume (P<0.05), percentage of the ‘foetal’ isomyosin V3 (P<0.05), and hydroxyproline concentration (P<0.05).
While the cause of the improved survival remains unknown, quinapril did apparently not interfere with the restitution of ‘foetal’ gene expression of pressure overloaded cardiomyocytes leading to depressed myocardial performance, ventricular dysfunction and the consecutive myocardial fibrosis.

British Journal of Pharmacology (2000) 130, 1671–1677; doi:10.1038/sj.bjp.0703467
Sulphonylurea drugs reduce hypoxic damage in the isolated perfused rat kidney
Authors: Engbersen Richard , Moons Miek M , Wouterse Alfons C , Dijkman Henry B , Kramers Cees , Smits Paul , Russel Frans G M 
Published: January 2005

Sulphonylurea drugs have been shown to protect against hypoxic damage in isolated proximal tubules of the kidney. In the present study we investigated whether these drugs can protect against hypoxic damage in a whole kidney preparation.
Tolbutamide (200 μM) and glibenclamide (10 μM) were applied to the isolated perfused rat kidney prior to changing the gassing from oxygen to nitrogen for 30 min.
Hypoxic perfusions resulted in an increased fractional excretion of glucose (FE % glucose 14.3±1.5 for hypoxic perfusions vs 4.9±1.6 for normoxic perfusions, mean±s.e.mean, P<0.05), which could be completely restored by 200 μM tolbutamide (5.7±0.4 for tolbutamide vs 14.3±1.5 for untreated hypoxic kidneys, P<0.01). Furthermore, tolbutamide reduced the total amount of LDH excreted in the urine (220±100 mU for tolbutamide vs 1220±160 mU for untreated hypoxic kidneys, P<0.01). Comparable results were obtained with glibenclamide (10 μM).
In agreement with the effect on functional parameters, ultrastructural analysis of proximal tubules showed increased brush border preservation in tolbutamide treated kidneys compared to untreated hypoxic kidneys.
We conclude that glibenclamide and tolbutamide are both able to reduce hypoxic damage to proximal tubules in the isolated perfused rat kidney when applied in the appropriate concentrations.

British Journal of Pharmacology (2000) 130, 1678–1684; doi:10.1038/sj.bjp.0703469
Bile acids increase intracellular Ca2+ concentration and nitric oxide production in vascular endothelial cells
Authors: Nakajima Toshiaki , Okuda Yukichi , Chisaki Keigo , Shin Wee‐Soo , Iwasawa Kuniaki , Morita Toshihiro , Matsumoto Akihiro , Suzuki Jun‐ichi , Suzuki Seizi , Yamada Nobuhiro , Toyo‐oka Teruhiko , Nagai Ryozo , Omata Masao 
Published: January 2005

The effects of bile acids on intracellular Ca2+ concentration [Ca2+]i and nitric oxide production were investigated in vascular endothelial cells.
Whole‐cell patch clamp techniques and fluorescence measurements of [Ca2+]i were applied in vascular endothelial cells obtained from human umbilical and calf aortic endothelial cells. Nitric oxide released was determined by measuring the concentration of NO2−.
Deoxycholic acid, chenodeoxycholic acid and the taurine conjugates increased [Ca2+]i concentration‐dependently, while cholic acid showed no significant effect. These effects resulted from the first mobilization of Ca2+ from an inositol 1,4,5‐triphosphate (IP3)‐sensitive store, which was released by ATP, then followed by Ca2+ influx.
Both bile acids and ATP induced the activation of Ca2+‐dependent K+ current. Oscillations of [Ca2+]i were occasionally monitored with the Ca2+‐dependent K+ current in voltage‐clamped cells and Ca2+ measurements of single cells.
The intracellular perfusion of heparin completely abolished the ATP effect, but failed to inhibit the bile acid effect.
Deoxycholic acid and chenodeoxycholic acid enhanced NO2− production concentration‐dependently, while cholic acid did not enhance it.
The bile acids‐induced nitric oxide production was suppressed by NG‐nitro‐L‐arginine methyl ester, exclusion of extracellular Ca2+ or N‐(6‐aminohexyl)‐5‐chloro‐l‐naphthalenesulphonamide hydrochloride (W‐7) and calmidazolium, calmodulin inhibitors.
These results provide novel evidence showing that bile acids increase [Ca2+]i and subsequently nitric oxide production in vascular endothelial cells. The nitric oxide production induced by bile acids may be involved in the pathogenesis of circulatory abnormalities in liver diseases including cirrhosis.

British Journal of Pharmacology (2000) 130, 1457–1467; doi:10.1038/sj.bjp.0703471
Regulation of lymphocyte proliferation by eosinophils via chymotrypsin‐like protease activity and adhesion molecule interaction
Authors: Matsunaga Yoichi , Shono Masayuki , Takahashi Mitsuo , Tsuboi Yoshio , Ogawa Kenichi , Yamada Tatsuo 
Published: January 2005

We investigated the regulatory mechanisms responsible for release of eosinophil cationic protein (ECP) from eosinophils activated by platelet‐activating factor (PAF) and monitored intra‐cellular pH (pHi) changes using a pH‐sensitive fluorescent probe. We also explored the mechanisms by which eosinophils suppress T‐lymphocyte proliferation induced by phytohaemagglutinin (PHA). In these experiments, a separated culture to investigate the ECP‐mediated pathway and a coculture to identify the adhesion molecules involved in eosinophil‐lymphocyte interactions were employed.
Chymostatin (1×10−6 M) inhibited ECP release by about 50% via stimulation by PAF or recombinant interleukin 5(rIL‐5) plus IgG.
PAF (1×10−7 M) raised eosinophil pHi from 6.9 to 7.3 within 20 s and pretreatment of these cells with chymostatin (1×10−6 M), but not with leupeptin or E64‐d, completely prevented this increase.
Calcium ionophore A23187 (1×10−7 M) induced ECP release and raised pHi to within a range similar to that of PAF, however, chymostatin had no effect on either.
Chymostatin reversed ECP‐mediated suppression of PHA‐induced T‐lymphocyte proliferation in separated cultures, but not in cocultures.
In coculture, eosinophils exhibited the same level of suppression of both CD4+ and CD8+ T‐cell proliferation in response to PHA.
Monoclonal antibodies against CD11a, CD18 and CD54, but not CD11b, restored eosinophil suppression of T‐lymphocyte proliferation which was chymostatin‐resistant in coculture.
Eosinophils were unable to suppress the proliferative response to lymphocytes to anti‐CD3 stimulation.
In conclusion, chymostatin specifically inhibited both the eosinophil pHi increase and ECP release induced by PAF. Eosinophils regulate PHA‐induced T‐lymphocyte proliferation via the ECP‐mediation associated with chymotrypsin‐like protease activity. These cells also control interactions with lymphocyte between adhesion molecules, CD11a, CD18 and CD54.

British Journal of Pharmacology (2000) 130, 1539–1546; doi:10.1038/sj.bjp.0703473
Hippocampal noradrenergic neurotransmission in concurrent EEG desynchronization and inhibition of penile erection induced by cocaine in the rat
Authors: Chang Alice Y W , Chan Julie Y H , Chan Samuel H H 
Published: January 2005

We previously reported that cocaine may induce activation of cortical (cEEG) and hippocampal (hEEG) electroencephalographic signals, concurrent with inhibition of penile erection, via an action on the hippocampal formation. The present study further evaluates the role of noradrenergic neurotransmission at the hippocampal formation in this process, using adult, male Sprague‐Dawley rats anaesthetized and maintained by chloral hydrate.
Unilateral microinjection of cocaine (100 nmoles) into the hippocampal CA1 or CA3 subfield or dentate gyrus elicited significant activation of both cEEG and hEEG activity. At the same time, the intracavernous pressure (ICP), our experimental index for penile erection, underwent a discernible reduction.
Co‐administration of equimolar doses (250 pmoles) of prazosin, naftopidil, yohimbine or rauwolscine significantly reversed those effects elicited by cocaine on cEEG, hEEG and ICP.
Microinjection unilaterally of equimolar doses (5 nmoles) of norepinephrine, phenylephrine or BHT 933 into the hippocampal formation, similar to cocaine, also induced appreciable cEEG and hEEG excitation, with a simultaneous decrease in ICP.
We conclude that cocaine may activate cEEG and hEEG and decrease ICP via noradrenergic neurotransmission, possibly engaging at least α1A/D‐, α2B‐ and α2C‐adrenoceptors at the hippocampal formation.

British Journal of Pharmacology (2000) 130, 1553–1560; doi:10.1038/sj.bjp.0703478
Mechanism of terfenadine block of ATP‐sensitive K+ channels
Authors: Zünkler Bernd J , Kühne Stephan , Rustenbeck Ingo , Ott Tilmann 
Published: January 2005

The ATP‐sensitive K+ (KATP) channel is a complex of a pore‐forming inwardly rectifying K+ channel (Kir6.2) and a sulphonylurea receptor (SUR). The aim of the present study was to gain further insight into the mechanism of block of KATP channels by terfenadine.
Channel activity was recorded both from native KATP channels from the clonal insulinoma cell line RINm5F and from a C‐terminal truncated form of Kir6.2 (Kir6.2Δ26), which – in contrast to Kir6.2 – expresses independently of SUR. Kir6.2Δ26 channels were expressed in COS‐7 cells, and enhanced green fluorescent protein (EGFP) cDNA was used as a reporter gene. EGFP fluorescence was visualized by a laser scanning confocal microscope.
Terfenadine applied to the cytoplasmic side of inside‐out membrane patches concentration‐dependently blocked both native KATP channel and Kir6.2Δ26 channel activity, and the following values were calculated for IC50 (the terfenadine concentration causing half‐maximal inhibition) and n (the Hill coefficient): 1.2 μM and 0.7 for native KATP channels, 3.0 μM and 1.0 for Kir6.2Δ26 channels.
Terfenadine had no effect on slope conductance of either native KATP channels or Kir6.2Δ26 channels. Intraburst kinetics of Kir6.2Δ26 channels were not markedly affected by terfenadine and, therefore, terfenadine acts as a slow channel blocker on Kir6.2Δ26 channels. Terfenadine‐induced block of Kir6.2Δ26 channels demonstrated no marked voltage dependence, and lowering the intracellular pH to 6.5 potentiated the inhibition of Kir6.2Δ26 channels by terfenadine.
These observations indicate that terfenadine blocks pancreatic B‐cell KATP channels via binding to the cytoplasmic side of the pore‐forming subunit. The presence of the pancreatic SUR1 has a small, but significant enhancing effect on the potency of terfenadine.

British Journal of Pharmacology (2000) 130, 1571–1574; doi:10.1038/sj.bjp.0703483
Sodium channel isoform‐specific effects of halothane: protein kinase C co‐expression and slow inactivation gating
Authors: Patel Manoj K , Mistry Dilaawar , Edward John J , Paul Mounsey J 
Published: January 2005

The modulatory effect of protein kinase C (PKC) on the response of Xenopus oocyte‐expressed Na channel α‐subunits to halothane (2‐bromo‐2‐chloro‐1,1,1‐trifluroethane) was studied. Na currents through rat skeletal muscle, rat brain and human cardiac muscle Na channels were assessed using cell‐attached patch clamp recordings. PKC activity was increased by co‐expression of a constitutively active PKC α‐isozyme.
Decay of macroscopic Na currents could be separated into fast and slow exponential phases.
PKC co‐expression alone slowed Na current decay in neuronal channels, through enhancement of the amplitude of the slower phase of decay.
Halothane (1.0 mM) was without effect on any of the three isoforms expressed alone but, after co‐expression of PKC, there was enhancement of Na current decay with reduction in charge movement through skeletal muscle and neuronal channels. Cardiac channels were relatively insensitive to halothane.
Enhanced Na current decay resulted from suppression of the slow phase, without effect on the faster phase or on either decay τ.
Suppression of Na current through skeletal muscle channels was concentration‐dependent over the therapeutic range and was described by third order reaction kinetics, with an IC50 of 0.55 mM.
We conclude that the halothane suppresses skeletal muscle and brain Na channel activity in this preparation through a reduction in the slow mode of inactivation gating, but only after PKC co‐expression. Cardiac Na channels were relatively insensitive to halothane. The mechanism is likely to involve phosphorylation of the channel inactivation gate, although phosphorylation of other sites in the channel may account for the isoform specific differences.

British Journal of Pharmacology (2000) 130, 1785–1792; doi:10.1038/sj.bjp.0703487
Modulation of cholinergic airway reactivity and nitric oxide production by endogenous arginase activity
Authors: Meurs Herman , Hamer Marco A M , Pethe Stephanie , Vadon‐Le Goff Sandrine , Boucher Jean‐Luc , Zaagsma Johan 
Published: January 2005

Cholinergic airway constriction is functionally antagonized by agonist‐induced constitutive nitric oxide synthase (cNOS)‐derived nitric oxide (NO). Since cNOS and arginase, which hydrolyzes L‐arginine to L‐ornithine and urea, use L‐arginine as a common substrate, competition between both enzymes for the substrate could be involved in the regulation of cholinergic airway reactivity. Using a perfused guinea‐pig tracheal tube preparation, we investigated the modulation of methacholine‐induced airway constriction by the recently developed, potent and specific arginase inhibitor NΩ‐hydroxy‐nor‐L‐arginine (nor‐NOHA).
Intraluminal (IL) administration of nor‐NOHA caused a concentration‐dependent inhibition of the maximal effect (Emax) in response to IL methacholine, which was maximal in the presence of 5 μM nor‐NOHA (Emax=31.2±1.6% of extraluminal (EL) 40 mM KCl‐induced constriction versus 51.6±2.1% in controls, P<0.001). In addition, the pEC50 (−log10 EC50) was slightly but significantly reduced in the presence of 5 μM nor‐NOHA.
The inhibition of Emax by 5 μM nor‐NOHA was concentration‐dependently reversed by the NOS inhibitor NΩ‐nitro‐L‐arginine methyl ester (L‐NAME), reaching an Emax of 89.4±7.7% in the presence of 0.5 mM L‐NAME (P<0.01). A similar Emax in the presence of 0.5 mM L‐NAME was obtained in control preparations (85.2±9.7%, n.s.).
In the presence of excess of exogenously applied L‐arginine (5 mM), 5 μM nor‐NOHA was ineffective (Emax=33.1±5.8 versus 31.1±7.5% in controls, n.s.).
The results indicate that endogenous arginase activity potentiates methacholine‐induced airway constriction by inhibition of NO production, presumably by competition with cNOS for the common substrate, L‐arginine. This finding may represent an important novel regulation mechanism of airway reactivity.

British Journal of Pharmacology (2000) 130, 1793–1798; doi:10.1038/sj.bjp.0703488