bluuebunny/crossref_metadata_2025 huggingface dataset:
Cytokine‐mediated inflammatory hyperalgesia limited by interleukin‐1 receptor antagonist
Authors: Cunha J M , Cunha F Q , Poole S , Ferreira S H
Published: January 2005

The effect of IL‐1ra on response to intraplantar (i.pl.) injection of LPS, carrageenin, bradykinin, TNFα, IL‐1β, IL‐8, PGE2 and dopamine was investigated in a model of mechanical hyperalgesia in rats.

IL‐1ra inhibited hyperalgesic response to LPS, carrageenin, bradykinin, TNFα, and IL‐1β, but not responses to IL‐8, PGE2 and dopamine.

A sheep anti‐rat IL‐1ra serum potentiated response to LPS, carrageenin, bradykinin, TNFα and IL‐1β but not IL‐8.

Carrageenin and LPS stimulated and production of immunoreactive TNFα, IL‐1β and IL‐1ra in the skin of injected paws.

The inhibition by IL‐1ra of the hyperalgesic response to carrageenin was not affected by antibodies neutralizing IL‐4 and IL‐10.

In mice, IL‐1ra inhibited the nociceptive response to i.p. injection of acetic acid.

These data suggest that IL‐1ra, released at sites of inflammation, limits inflammatory hyperalgesia. This effect is independent of (IL‐1ra‐induced) IL‐4 and IL‐10 and appears to be the result of antagonism by IL‐1ra of IL‐1β‐stimulated eicosanoid production.

British Journal of Pharmacology (2000) 130, 1418–1424; doi:10.1038/sj.bjp.0703434
Inotropic response to endothelin‐1, isoprenaline and calcium in cardiomyocytes isolated from endotoxin treated rats: effects of ethyl‐isothiourea and dexamethasone
Authors: Spiers J P , Kelso E J , Allen J D , Silke B , McDermott B J
Published: January 2005

The contractile effects of endothelin‐1, isoprenaline and extracellular calcium were assessed on ventricular cardiomyocytes isolated from lipopolysaccharide‐treated rats. The involvement of nitric oxide was investigated using dexamethasone (in vivo) and ethyl isothiourea (in vitro).

Male Wistar rats (n=70) were injected with either saline (1 ml kg−1) or lipopolysaccharide (LPS; 5 mg kg−1) alone, or following pre‐treatment with dexamethasone (DEX+LPS; 5 mg kg−1). Ventricular cell shortening was recorded using a video edge detection system, and concentration‐response relationships were established for endothelin‐1, isoprenaline and calcium, in the absence or presence of ethyl isothiourea (ETU; 10 μM). iNOS expression was assessed using reverse transcription‐polymerase chain reaction.

iNOS mRNA expression was greater (P<0.001) in the LPS (iNOS/GAPDH ratio: 0.90±0.09) treated group compared to saline (iNOS/GAPDH ratio: 0.36±0.02). Baseline contractile amplitude was reduced (P<0.05) in the LPS (7.3±0.2 μm) and DEX+LPS groups (6.7±0.3 μm) compared to saline (8.0±0.2 μm).

The concentration‐dependent contractile response to endothelin‐1 was attenuated (P<0.05) in the LPS group compared to saline (maximum change: 0.45±0.2 vs 1.8±0.2 μm). Neither ETU nor dexamethasone improved contractile function in the LPS‐treated animals.

The concentration‐dependent increase in the contractile response to isoprenaline was attenuated in the LPS‐treated group compared to saline (P<0.05; maximum change: 1.7±0.4 vs 3.1±0.4 μm). This effect was reversed by ETU (maximum change: 3.7±0.6 μm). Pre‐treatment with dexamethasone prevented a significant fall in contraction amplitude (maximum change: 2.4±0.4 μm).

The contractile response to calcium was reduced (P<0.05) in the LPS group compared to saline (maximum change: 8.7±0.6 vs 10.7±0.8 μm). Neither ETU nor dexamethasone restored contractile function in the LPS‐treated group.

In conclusion, a nitric oxide‐mediated inhibitory pathway is not responsible for the diminished contractile response to either endothelin‐1 or extracellular calcium, but contributes to the hyporesponsiveness to isoprenaline in lipopolysaccharide treated rats.

British Journal of Pharmacology (2000) 130, 1275–1282; doi:10.1038/sj.bjp.0703435
Role of central glutamate receptors, nitric oxide and soluble guanylyl cyclase in the inhibition by endotoxin of rat gastric acid secretion
Authors: García‐Zaragozá Eugenia , Barrachina M Dolores , Moreno Lucrecia , Esplugues Juan V
Published: January 2005

This study examines the role of a central pathway involving glutamate receptors, nitric oxide (NO) and cyclic GMP in the acute inhibitory effects of low doses of peripheral endotoxin on pentagastrin‐stimulated acid production.

Vagotomy or intracisternal (i.c.) microinjections of the NO‐inhibitor, NG‐nitro‐L‐arginine methyl esther (L‐NAME; 200 μg rat−1) restored acid secretory responses in endotoxin (10 μg kg−1, i.v.)‐treated rats.

The acid‐inhibitory effect of i.v. endotoxin (10 μg kg−1, i.v.) was prevented by prior i.c. administration of the NMDA receptor antagonists, dizocilpine maleate (MK‐801; 10 nmol rat−1) and D‐2‐amino‐5‐phosphono‐valeric acid (AP‐5; 20 nmol rat−1), or the AMPA/kainate antagonist 6,7‐dinitroquinoxaline‐2,3‐dione (DNQX; 10 nmol rat−1). However, the competitive metabotropic glutamate receptor antagonist (+)‐α‐methyl‐4‐carboxyphenylglycine (MCPG; 20–1000 nmol rat−1) did not antagonize the effects of endotoxin.

I.c. administration of L‐glutamate (0.1 nmol rat−1) inhibited pentagastrin‐stimulated gastric acid secretion. Coadministration with L‐NAME (200 μg rat−1) prevented the inhibition of gastric acid secretion by the aminoacid.

I.c. administration of 1H‐[1,2,4]Oxazodiolo[4,3‐a]quinoxalin‐1‐one (ODQ; 100 nmol rat−1), a soluble guanylyl cyclase (sGC) blocker, reversed the hyposecretory effect of endotoxin.

I.c. administration of the cyclic GMP analogue 8‐Bromoguanosine‐3,5‐cyclic monophosphate (8‐Br‐cGMP; 100–300 nmol rat−1) reduced gastric acid production in a dose‐dependent manner.

We conclude that central NMDA and AMPA/kainate receptors are involved in the acid inhibitory effect of peripherally administered endotoxin. This central pathway involves synthesis of NO, which acts on the enzyme sGC.

British Journal of Pharmacology (2000) 130, 1283–1288; doi:10.1038/sj.bjp.0703436
YD‐3, a novel inhibitor of protease‐induced platelet activation
Authors: Wu Chin‐Chung , Huang Shiow‐Wen , Hwang Tsong‐Long , Kuo Sheng‐Chu , Lee Fang‐Yu , Teng Che‐Ming
Published: January 2005

In the present study, the antiplatelet effects and mechanisms of a new synthetic compound YD‐3 [1‐benzyl‐3(ethoxycarbonylphenyl)‐indazole] were examined.

YD‐3 inhibited the aggregation of washed rabbit platelets caused by thrombin (IC50=28.3 μM), but had no or little inhibitory effect on that induced by arachidonic acid, collagen, platelet‐activating factor (PAF) or U46619. YD‐3 also suppressed generation of inositol phosphates caused by thrombin. On the other hand, thrombin‐induced fibrin formation was not affected by YD‐3, indicating YD‐3 does not inhibit the proteolytic activity of thrombin.

In washed human platelets, however, YD‐3 had only mild inhibitory effect on the low concentration (0.05 u ml−1) of thrombin‐induced human platelet aggregation, and did not affect that induced by higher concentrations (0.1 u ml−1) of thrombin or SFLLRN, the protease‐activated receptor 1 (PAR1) agonist peptide. By contrast, YD‐3 inhibited both human and rabbit platelet aggregation elicited by trypsin with IC50 values of 38.1 μM and 5.7 μM, respectively.

YD‐3, at 100 μM, had no effect on ristocetin‐induced glycoprotein Ib (GPIb)‐dependent aggregation of human platelets. In addition, platelets treated with chymotrypsin, which cleaves GPIb, enhanced rather than attenuated the inhibition of YD‐3 on thrombin‐induced human platelet aggregation. These data indicate that GPIb plays no role in the antiplatelet effect of YD‐3.

In SFLLRN‐desensitized human platelets, high concentration of thrombin (1 u ml−1) could still elicit intracellular Ca2+ mobilization, and the rise of [Ca2+]i was prevented by either leupeptin or YD‐3.

Our results suggest that YD‐3 inhibits a non‐PAR1 thrombin receptor which mediates the major effect of thrombin in rabbit platelets, but in human platelets, this receptor function becomes significant only when the function of PAR1 has been blocked or attenuated.

British Journal of Pharmacology (2000) 130, 1289–1296; doi:10.1038/sj.bjp.0703437
Novel proline endopeptidase inhibitors do not modify Aβ40/42 formation and degradation by human cells expressing wild‐type and Swedish mutated β‐amyloid precursor protein
Authors: Petit Agnès , Barelli Hélène , Morain Philippe , Checler Frédéric
Published: January 2005

Previous studies have suggested that proline endopeptidase (PE) could participate to the catabolism of the β‐amyloid peptide (Aβ) or to the physiopathological maturation of the β‐amyloid protein precursor (βAPP). We have examined the putative ability of human purified PE to catabolize Aβ40 and Aβ42 and the possible contribution of this enzyme to the generation of Aβ40 and Aβ42 in human HEK293 cells.

We show first that purified human PE does not degrade synthetic Aβ40 and Aβ42, in vitro.

We establish that HEK293 cell homogenates exhibit a Z‐Gly‐Pro‐7AMC‐cleaving enzyme, the activity of which is inhibited by Z‐Pro‐Prolinal and S17092 and S19825, two novel PE inhibitors, with affinities similar to those displayed on the purified human PE. These inhibitors also penetrate cells and achieve a full inhibition of endogenous proline endopeptidase in human cells.

By means of selective antibodies directed towards the C‐terminal of Aβ40 and Aβ42, we assessed the effect of PE inhibitors on the recovery of both Aβ species. This was examined in HEK293 cells stably overexpressing the wild‐type and the familial Alzheimer' disease‐related Swedish mutated β‐APP. We establish that none of these inhibitors affected Aβ40 or Aβ42 production in these transfected cells.

Overall, our study indicates that human PE does not degrade Aβ40 and Aβ42. Furthermore, PE does not contribute to Aβ40 and Aβ42 formation in HEK293 cells. Therefore, PE does not appear to contribute to the Aβ‐related aetiology of Alzheimer' disease.

British Journal of Pharmacology (2000) 130, 1613–1617; doi:10.1038/sj.bjp.0703440
[Ca2+]i‐ and insulin‐stimulating effect of the non‐membranepermeable phosphatase‐inhibitor microcystin‐LR in intact insulin‐secreting cells (RINm5F)
Authors: Leiers T , Bihlmayer A , Ammon H P T , Wahl M A
Published: January 2005

Microcystin‐LR, a specific and effective inhibitor of serine/threonine phosphatases type 1/2A which does not permeate cells, was used to distinguish intracellular and extracellular effects of phosphatase inhibitors on insulin secretion by RINm5F cells.

Incubation of intact RINm5F cells with microcystin‐LR (0.1–2 μM) almost doubled basal insulin release at 3 mM glucose but left maximal insulin release induced by KCl (30 mM) unaffected.

In parallel, there was an increase in cytosolic Ca2+ by up to half maximum, which could be suppressed by the Ca2+‐channel blocker D600.

In contrast, microcystin‐LR incubation of intact cells did not affect phosphatase activity but significantly reduced phosphatase activity when used in cellular fractions.

From these data we conclude that microcystin‐LR could affect Ca2+‐channels and insulin release by inhibiting an extracellular phosphatase‐like activity.

British Journal of Pharmacology (2000) 130, 1406–1410; doi:10.1038/sj.bjp.0703441
Low dose carvedilol inhibits progression of heart failure in rats with dilated cardiomyopathy
Authors: Watanabe Kenichi , Ohta Yoshimi , Nakazawa Mikio , Higuchi Hiroshi , Hasegawa Go , Naito Makoto , Fuse Koichi , Ito Masahiro , Hirono Satoru , Tanabe Naohito , Hanawa Haruo , Kato Kiminori , Kodama Makoto , Aizawa Yoshifusa
Published: January 2005

The cardioprotective properties of carvedilol (a vasodilating β‐adrenoceptor blocking agent) were studied in a rat model of dilated cardiomyopathy induced by autoimmune myocarditis.

Twenty‐eight days after immunization, surviving Lewis rats (32/43=74%) were divided into three groups to be given 2 mg kg−1 day−1 (Group‐C2, n=10) or 20 mg kg−1 day−1 (Group‐C20, n=10) of carvedilol, or vehicle (0.5% methylcellulose, Group‐V, n=12).

After oral administration for 2 months, body weight, heart weight (HW), heart rate (HR), rat α‐atrial natriuretic peptide (r‐ANP) in blood, central venous pressure (CVP), mean blood pressure (mean BP), peak left ventricular pressure (LVP), left ventricular end‐diastolic pressure (LVEDP), ±dP dt−1 and area of myocardial fibrosis were measured. Values were compared with those for normal Lewis rats (Group‐N, n=10).

Two out of 12 (17%) rats in Group‐V died from day 28 to day 42 after immunization. No rat died in Groups‐C2, ‐C20 and ‐N. Although the CVP, mean BP, LVP and ±dP dt−1 did not differ among the three groups, the HW, HR and r‐ANP in Group‐C2 (1.14±0.03, 339±16 and 135±31) and Group‐C20 (1.23±0.04, 305±8 and 156±24) were significantly lower than those in Group‐V (1.36±0.04 g, 389±9 beats min−1 and 375±31 pg ml−1, respectively). The LVEDP in Group‐C2 was significantly lower than that in Group‐V (7.4±1.4 and 12.2±1.2 mmHg, respectively, P<0.05). The area of myocardial fibrosis in Group‐C2 was smaller than that in Group‐V (12±1 and 31±2%, P<0.01).

These results indicate that a low dose of carvedilol has beneficial effects on dilated cardiomyopathy.

British Journal of Pharmacology (2000) 130, 1489–1495; doi:10.1038/sj.bjp.0703450
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
The importance of ERK activity in the regulation of cyclin D1 levels and DNA synthesis in human cultured airway smooth muscle
Authors: Ravenhall Claire , Guida Elizabeth , Harris Trudi , Koutsoubos Valentina , Stewart Alastair
Published: January 2005

The relationship between persistent ERK (extracellular signal‐regulated kinase) activity, cyclin D1 protein and mRNA levels and cell cycle progression in human cultured airway smooth muscle was examined in response to stimulation by ET‐1 (endothelin‐1), thrombin and bFGF (basic fibroblast growth factor).

Thrombin (0.3 and 3 u ml−1) and bFGF (0.3 and 3 nM) increased ERK activity for more than 2 h and increased cell number, whereas ET‐1 (100 nM) transiently stimulated ERK activity and was non‐mitogenic.

The MEK1 (mitogen‐activated ERK kinase) inhibitor, PD 98059 (30 μM), inhibited both ERK phosphorylation and activity, and either prevented (thrombin 0.3 and 3 u ml−1, bFGF 300 pM) or attenuated (bFGF 3 nM) DNA synthesis.

Thrombin and bFGF increased both cyclin D1 mRNA and protein levels. PD 98059 decreased cyclin D1 protein levels stimulated by the lower but not higher thrombin concentrations. Moreover, increases in cyclin D1 mRNA levels were unaffected by PD 98059 pretreatment, irrespective of the mitogen or its concentration, suggesting that inhibition of cyclin D1 protein levels occurred by a post‐transcriptional mechanism.

These findings indicate that the control of cyclin D1 protein levels may occur independently of the MEK1/ERK signalling pathways. The inhibition of S phase entry by PD 98059 at higher thrombin concentrations appears to result from effects on pathways downstream or parallel to those regulating cyclin D1 protein levels. These findings suggest heterogeneity in the signalling of DNA synthesis in human cultured airway smooth muscle.

British Journal of Pharmacology (2000) 131, 17–28; doi:10.1038/sj.bjp.0703454
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
Calcium‐pH crosstalks in rat mast cells: cytosolic alkalinization, but not intracellular calcium release, is a sufficient signal for degranulation
Authors: Alfonso A , Cabado A G , Vieytes M R , Botana L M
Published: January 2005

The aim of this work was to study the relationship between intracellular alkalinization, calcium fluxes and histamine release in rat mast cells. Intracellular alkalinization was induced by nigericin, a monovalent cation ionophore, and by NH4Cl (ammonium chloride). Calcium cytosolic and intracellular pH were measured by fluorescence digital imaging using Fura‐2‐AM and BCECF‐AM.

In rat mast cells, nigericin and NH4Cl induce a dose‐dependent intracellular alkalinization, a dose‐dependent increase in intracellular calcium levels by releasing calcium from intracellular pools, and an activation of capacitative calcium influx.

The increase in both intracellular calcium and pH activates exocytosis (histamine release) in the absence of external calcium. Under the same conditions, thapsigargin does not activate exocytosis, the main difference being that thapsigargin does not alkalinize the cytosol.

After alkalinization, histamine release is intracellular‐calcium dependent. With 2.5 mM EGTA and thapsigargin the cell response decreases by 62%.

The cytosolic alkalinization, in addition to the calcium increase it is enough signal to elicit the exocytotic process in rat mast cells.

British Journal of Pharmacology (2000) 130, 1809–1816; doi:10.1038/sj.bjp.0703490
Selective monoamine oxidase subtype inhibition and striatal extracellular dopamine in the guinea‐pig
Authors: Ilani T , Lamensdorf I , Finberg J P M
Published: January 2005

Striatal microdialysate levels of dopamine (DA) in conscious guinea‐pigs were measured following acute (1 day) and chronic (21 days) treatment with deprenyl (2 and 0.25 mg kg−1 s.c., respectively) or clorgyline (4 and 1 mg kg−1 s.c., respectively), as well as by combination treatment using the same doses of the two inhibitors. These treatments caused selective inhibition of monoamine oxidase type B (MAO‐B) or monoamine oxidase type A (MAO‐A) respectively.

Neither acute nor chronic treatments with deprenyl or clorgyline increased basal or KCl‐induced DA levels. Acute and chronic clorgyline treatments were accompanied by significant reductions in striatal microdialysate 3,4‐dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA). On the other hand, both acute and chronic deprenyl treatments were accompanied by significant increases in microdialysate HVA with no effect on DOPAC levels.

Acute or chronic combined treatment with clorgyline and deprenyl increased tissue but not microdialysate DA levels. The combination treatment given chronically also reduced KCl‐induced DA release but enhanced amphetamine‐induced DA release.

Microdialysate DA levels increased to a smaller extent in guinea‐pig than in rat following local striatal infusion of GBR‐12909 (100 μM).

The difference between guinea‐pigs and rats in the response to GBR‐12909, could be the result of a lower dopaminergic innervation and/or density of DA transporter. This difference may explain why striatal microdialysate DA levels increased following chronic deprenyl treatment in the rat but not in the guinea‐pig.

British Journal of Pharmacology (2000) 130, 1992–1998; doi:10.1038/sj.bjp.0703493
Latency to paroxetine‐induced anxiolysis in the rat is reduced by co‐administration of the 5‐HT1A receptor antagonist WAY100635
Authors: Duxon M S , Starr K R , Upton N
Published: January 2005

We report here the use of rat high‐light social interaction to model the temporal anxiolytic/antidepressant effects of SSRIs seen in the clinic. Compared to vehicle controls, 21, but not 14, days of paroxetine treatment (3 mg kg−1, p.o., daily) produced a marked increase in rat social interaction (Vehicle=71.3±7.3 s; Paroxetine=116.7±14.7 s; P<0.01) with no concurrent effect on locomotor activity, consistent with anxiolysis.

To assess whether concurrent 5‐HT1A receptor blockade reduces the time to onset of anxiolysis seen with paroxetine alone (21 days), rats were implanted with osmotic minipumps to continuously infuse the 5‐HT1A receptor antagonist WAY100635 (1 mg kg−1 day−1, s.c., 7 days) alone or in combination with paroxetine (3 mg kg−1, p.o., daily, 7 days), prior to anxiety testing. Paroxetine (Veh/Par=61.9±7.9 s) or WAY100635 (WAY/Veh=71.6±4.7 s) alone, had no effect on social interaction time compared to vehicle treated controls (Veh/Veh=76.4±4.9 s), whilst coadministration of WAY100635 with paroxetine, produced a marked elevation in social interaction (WAY/Par=149.3±16.8 s; P<0.01) relative to all other groups with no concurrent change in locomotor activity.

In contrast, acute administration of WAY100635 (0.03 mg kg−1, s.c.) with paroxetine (3 mg kg−1, p.o.) did not alter any behavioural measure, suggesting that the anxiolysis induced by the combination after 7 days is attributable to a CNS adaptive response.

This data demonstrates that coadministration of a 5‐HT1A receptor antagonist with paroxetine markedly reduces the latency to anxiolysis, in the rat.

This study supports the use of the rat social interaction test to further delineate adaptive changes in the CNS responsible for the anxiolytic/antidepressant action of SSRIs seen in humans.

British Journal of Pharmacology (2000) 130, 1713–1719; doi:10.1038/sj.bjp.0703496
Characterization of the effects of cannabinoids on guinea‐pig tracheal smooth muscle tone: role in the modulation of acetylcholine release from parasympathetic nerves
Authors: Spicuzza Lucia , Haddad El‐Bdaoui , Birrell Mark , Ling Andrea , Clarke Deborah , Venkatesan Priya , Barnes Peter J , Belvisi Maria G
Published: January 2005

We investigated the ability of the cannabinoid agonists CP55,940 (CB1/CB2) and anandamide (endogenous cannabinoid) to modulate electrical field stimulation (EFS)‐induced acetylcholine (ACh) release from parasympathetic nerve terminals innervating guinea‐pig trachea. We assessed whether modulation of transmitter release translated to an impact on functional responses by investigating the effect of these agents on contractile responses evoked by EFS and ACh. Furthermore, we evaluated the ability of these compounds to elicit bronchodilation in pre‐contracted guinea‐pig tracheal strips.

CP55,940 and anandamide significantly inhibited EFS‐evoked ACh release (maximal inhibition of 35.1±2.9% and 33.4±6.4% at 1 μM, P<0.05, respectively). The CB1 receptor antagonist SR 141716A (1 μM), had no effect on ACh release and failed to reverse the inhibitory effect of CP55,940 (1 μM).

Paradoxically, CP55,940 had no significant effect on EFS‐evoked cholinergic contractile responses. Furthermore, CP55,940 did not relax pre‐contracted tracheal strips or affect contractile responses to exogenous ACh. This lack of activity on smooth muscle tone is consistent with the fact that no detectable specific binding of [3H] CP55,940 was found in tracheal homogenates.

These data suggest that cannabinoid agonists inhibit ACh release from cholinergic nerve terminals via activation of CB2 receptors but that this inhibitory action does not impact on functional responses such as cholinergic contraction.

British Journal of Pharmacology (2000) 130, 1720–1726; doi:10.1038/sj.bjp.0703497