bluuebunny/crossref_metadata_2025_split huggingface dataset:
Endothelium‐derived hyperpolarizing factor and potassium use different mechanisms to induce relaxation of human subcutaneous resistance arteries
Authors: McIntyre C‐A , Buckley C H , Jones G C , Sandeep T C , Andrews R C , Elliott A I , Gray G A , Williams B C , McKnight J A , Walker B R , Hadoke P W F 
Published: January 2005

This investigation examined the hypothesis that release of K+ accounts for EDHF activity by comparing relaxant responses produced by ACh and KCl in human subcutaneous resistance arteries.
Resistance arteries (internal diameter 244±12 μm, n=48) from human subcutaneous fat biopsies were suspended in a wire myograph. Cumulative concentration‐response curves were obtained for ACh (10−9 – 3×10−5 M) and KCl (2.5 – 25 mM) following contraction with noradrenaline (NA; 0.1 – 3 μM).
ACh (Emax 99.07±9.61%; −LogIC50 7.03±0.22; n=9) and KCl (Emax 74.14±5.61%; −LogIC50 2.12±0.07; n=10)‐induced relaxations were attenuated (P<0.0001) by removal of the endothelium (Emax 8.21±5.39% and 11.56±8.49%, respectively; n=6 – 7).
Indomethacin (10 μM) did not alter ACh‐induced relaxation whereas L‐NOARG (100 μM) reduced this response (Emax 61.7±3.4%, P<0.0001; n=6). The combination of ChTx (50 nM) and apamin (30 nM) attenuated the L‐NOARG‐insensitive component of ACh‐induced relaxation (Emax: 15.2±10.5%, P<0.002, n=6) although these arteries retained the ability to relax in response to 100 μM SIN‐1 (Emax 127.6±13.0%, n=3). Exposure to BaCl2 (30 μM) and Ouabain (1 mM) did not attenuate the L‐NOARG resistant component of ACh‐mediated relaxation (Emax, 76.09±8.92, P=0.16; n=5).
KCl‐mediated relaxation was unaffected by L‐NOARG+indomethacin (Emax; 68.1±5.6%, P=0.33; n=5) or the combination of L‐NOARG/indomethacin/ChTx/apamin (Emax; 86.61±14.02%, P=0.35; n=6). In contrast, the combination of L‐NOARG, indomethacin, ouabain and BaCl2 abolished this response (Emax, 5.67±2.59%, P<0.0001, n=6).
The characteristics of KCl‐mediated relaxation differed from those of the nitric oxide/prostaglandin‐independent component of the response to ACh, and were endothelium‐dependent, indicating that K+ does not act as an EDHF in human subcutaneous resistance arteries.

British Journal of Pharmacology (2001) 133, 902–908; doi:10.1038/sj.bjp.0704143
Modulation of haem oxygenase‐1 expression by nitric oxide and leukotrienes in zymosan‐activated macrophages
Authors: Vicente Ana María , Guillén María Isabel , Alcaraz María José 
Published: January 2005

Phagocytosis of unopsonized zymosan by RAW 264.7 macrophages upregulated protein expression of haem oxygenase‐1 (HO‐1), inducible nitric oxide synthase (iNOS) and cyclo‐oxygenase‐2 (COX‐2) in a time‐ and concentration‐dependent manner.
In the presence of zymosan, exogenous prostaglandin E2 (PGE2) did not exert significant effects on the expression of these three enzymes. In contrast, exogenous leukotriene B4 (LTB4) and LTC4 in the nanomolar range inhibited HO‐1 and iNOS expression, as well as nitrite accumulation.
The COX inhibitors indomethacin and NS398 weakly inhibited HO‐1 expression but had no effect on iNOS and COX‐2 expression or nitrite. In contrast, the 5‐lipoxygenase (5‐LO) inhibitor ZM 230,487 significantly decreased HO‐1, iNOS and nitrite, which were not affected by zileuton. Dexamethasone showed an inhibitory effect on HO‐1 expression induced by zymosan.
ZM 230,487 but not zileuton, inhibited the shift due to nuclear factor‐κB (NF‐κB), whereas they did not modify activator protein‐1 (AP‐1) binding. Our results suggest that inhibition of NF‐κB binding could mediate the effects of ZM 230,487 on the modulation of HO‐1 and iNOS protein expression.
NOS inhibition by L‐NG‐nitroarginine methyl ester (L‐NAME) or 1400 W abolished nitrite production and strongly reduced HO‐1 expression. These results show an induction of HO‐1 protein expression by zymosan phagocytosis in macrophages, with a positive modulatory role for endogenous NO and a negative regulation by exogenous LTs, likely dependent on the reduction of iNOS expression and NO production.

British Journal of Pharmacology (2001) 133, 920–926; doi:10.1038/sj.bjp.0704145
Ibudilast attenuates astrocyte apoptosis via cyclic GMP signalling pathway in an in vitro reperfusion model
Authors: Takuma K , Lee E , Enomoto R , Mori K , Baba A , Matsuda T 
Published: January 2005

We examined the effect of 3‐isobutyryl‐2‐isopropylpyrazolo[1,5‐a]pyridine (ibudilast), which has been clinically used for bronchial asthma and cerebrovascular disorders, on cell viability induced in a model of reperfusion injury.
Ibudilast at 10 – 100 μM significantly attenuated the H2O2‐induced decrease in cell viability.
Ibudilast inhibited the H2O2‐induced cytochrome c release, caspase‐3 activation, DNA ladder formation and nuclear condensation, suggesting its anti‐apoptotic effect.
Phosphodiesterase inhibitors such as theophylline, pentoxyfylline, vinpocetine, dipyridamole and zaprinast, which increased the guanosine‐3′,5′‐cyclic monophosphate (cyclic GMP) level, and dibutyryl cyclic GMP attenuated the H2O2‐induced injury in astrocytes.
Ibudilast increased the cyclic GMP level in astrocytes.
The cyclic GMP‐dependent protein kinase inhibitor KT5823 blocked the protective effects of ibudilast and dipyridamole on the H2O2‐induced decrease in cell viability, while the cyclic AMP‐dependent protein kinase inhibitor KT5720, the cyclic AMP antagonist Rp‐cyclic AMPS, the mitogen‐activated protein/extracellular signal‐regulated kinase inhibitor PD98059 and the leukotriene D4 antagonist LY 171883 did not.
KT5823 also blocked the effect of ibudilast on the H2O2‐induced cytochrome c release and caspase‐3‐like protease activation.
These findings suggest that ibudilast prevents the H2O2‐induced delayed apoptosis of astrocytes via a cyclic GMP, but not cyclic AMP, signalling pathway.

British Journal of Pharmacology (2001) 133, 841–848; doi:10.1038/sj.bjp.0704146
Effects of sufentanil and NMDA antagonists on a C‐fibre reflex in the rat
Authors: Adam Frédéric , Gairard Anne Cécile , Chauvin Marcel , Bars Daniel Le , Guirimand Frédéric 
Published: January 2005

The effects of intravenous sufentanil and pre‐administration of N‐methyl‐D‐aspartate (NMDA) receptor antagonists were tested on a reflex triggered by C‐fibre activation. The reflex was elicited by electrical stimulation of the sural nerve and recorded from the ipsilateral biceps femoris muscle in halothane anaesthetized rats either (1) with an intact neuraxis or (2) in which the brain had previously been transected at the level of the obex.
All four doses of sufentanil (0.33, 0.6, 1 and 2 μg kg−1) elicited a depression of the reflex in a dose‐dependent manner. However, following the expected depression, all doses of sufentanil elicited both facilitation of the reflex and tonic inter‐stimulus discharges.
The C‐fibre reflex was not modified following intravenous ketamine (1 mg kg−1) or (+)‐HA966 (5 or 10 mg kg−1) but, when administered 5 min before sufentanil, these drugs enhanced both the extent and the duration of the depression and strongly reduced the facilitations.
In the obex‐transected rats, the depressive effect of 1 μg kg−1 sufentanil increased, while the facilitation of the C‐fibre reflex and the tonic inter‐stimulus discharges disappeared. Pre‐administration of 10 mg kg−1 (+)‐HA966 reinforced and prolonged the depressive effect of sufentanil.
These results extend previous studies suggesting the involvement of NMDA receptors in the spinal transmission of nociceptive signals. They illustrate the potential of spinal NMDA receptor blockade to both enhance the analgesic, and prevent the pro‐nociceptive, effects of sufentanil.

British Journal of Pharmacology (2001) 133, 1013–1022; doi:10.1038/sj.bjp.0704148
Role of the extracellular signal‐regulated kinase (Erk) signal transduction cascade in α2 adrenoceptor‐mediated vasoconstriction in porcine palmar lateral vein
Authors: Roberts R E 
Published: January 2005

The mechanism of α2 adrenoceptor‐mediated vasoconstriction is unknown, but may involve activation of voltage‐sensitive calcium channels, and/or a protein tyrosine kinase. Recently the extracellular signal‐regulated kinase (Erk) cascade, often an event downstream of tyrosine kinase activation, has been shown to mediate vasoconstriction to a variety of agents. The aim of this present study was to determine the involvement of the Erk signal transduction cascade in α2 adrenoceptor‐mediated vasoconstriction, and to confirm the involvement of activation of voltage‐sensitive calcium channels, and protein tyrosine kinase.
Contractions to the α2 adrenoceptor agonist UK14304 in the porcine palmar lateral vein in vitro were reduced 70 – 80% by the MEK inhibitors PD98059 (10 – 50 μM) and U0126 (10 – 50 μM), indicating the involvement of the Erk signal transduction cascade. Immunoblots also demonstrated an increase in the phosphorylated (activated) form of Erk in palmar lateral vein segments after contraction with UK14304, which was inhibited by PD98059 and U0126.
The calcium channel blockers nifedipine and verapamil, or removal of extracellular calcium inhibited UK14304‐induced contractions and phosphorylation of Erk, demonstrating the importance of an influx of extracellular calcium. UK14304‐induced contractions were inhibited by PP2 (1 – 10 μM), a selective inhibitor of Src tyrosine kinases, but not by PP3, an inactive analogue. PP2 also prevented the phosphorylation of Erk by UK14304.
These data demonstrate that α2 adrenoceptor‐mediated vasoconstriction in the porcine palmar lateral vein is dependent upon activation of the Erk signal transduction cascade, which is downstream of an influx of extracellular calcium, and activation of Src tyrosine kinases.

British Journal of Pharmacology (2001) 133, 859–866; doi:10.1038/sj.bjp.0704149
Inhibition of DNA synthesis in cultured hepatocytes by endotoxin‐conditioned medium of activated stellate cells is transforming growth factor‐β and nitric oxide‐independent
Authors: Uemura Tadahiro , Gandhi Chandrashekhar R 
Published: January 2005

Activated hepatic stellate cells play a major role in the pathophysiology of chronic liver disease. They can influence the metabolism of hepatocytes by producing a variety of cytokines and growth factors. Upon stimulation with endotoxin, stellate cells also synthesize nitric oxide (NO), a potent mediator of growth of several cell types including hepatocytes.
We investigated the effect of serum‐free medium conditioned by activated stellate cells in the absence and presence of endotoxin on NO and DNA synthesis in hepatocytes. Stellate cells and hepatocytes were isolated by enzymatic digestion of the liver. Stellate cells were cultured for 10 days after which the majority exhibited α‐smooth muscle actin (a marker for activated cells); hepatocytes were used after overnight culture.
While the medium conditioned by stellate cells in the absence of endotoxin stimulated DNA synthesis in hepatocytes, medium conditioned in its presence inhibited this process in an endotoxin concentration‐dependent manner (10–1000 ng ml−1). Endotoxin‐conditioned stellate cell medium also stimulated NO synthesis in hepatocytes; the effect was consistent with increased protein and mRNA expression of inducible NO synthase (iNOS). However, inhibition of DNA synthesis in hepatocytes caused by endotoxin‐conditioned stellate cell medium was unaffected by the NOS inhibitor, L‐NG‐monomethylarginine (L‐NMMA), guanylyl cyclase inhibitor 1H‐[1,2,4]oxadiazolo[4,3‐a]quinoxalin‐1‐one (ODQ), and neutralizing antibodies for TGF‐β, IL‐1β, IL‐6 and TNF‐α.
These results indicate that factors other than these cytokines produced by activated stellate cells upon stimulation with endotoxin or by hepatocytes challenged with endotoxin‐conditioned stellate cell medium inhibit DNA synthesis in hepatocytes.

British Journal of Pharmacology (2001) 133, 1125–1133; doi:10.1038/sj.bjp.0704151
Agonists of proteinase‐activated receptor 1 induce plasma extravasation by a neurogenic mechanism
Authors: Garavilla Lawrence de , Vergnolle Nathalie , Young Steven H , Ennes Helena , Steinhoff Martin , Ossovskaya Valeria S , D'Andrea Michael R , Mayer Emeran A , Wallace John L , Hollenberg Morley D , Andrade‐Gordon Patricia , Bunnett Nigel W 
Published: January 2005

Thrombin, generated in the circulation during injury, cleaves proteinase‐activated receptor 1 (PAR1) to stimulate plasma extravasation and granulocyte infiltration. However, the mechanism of thrombin‐induced inflammation in intact tissues is unknown. We hypothesized that thrombin cleaves PAR1 on sensory nerves to release substance P (SP), which interacts with the neurokinin 1 receptor (NK1R) on endothelial cells to cause plasma extravasation.
PAR1 was detected in small diameter neurons known to contain SP in rat dorsal root ganglia by immunohistochemistry and in situ hybridization.
Thrombin and the PAR1 agonist TFLLR‐NH2 (TF‐NH2) increased [Ca2+]i >50% of cultured neurons (EC50s 24 mu ml−1 and 1.9 μM, respectively), assessed using Fura‐2 AM. The PAR1 agonist completely desensitized responses to thrombin, indicating that thrombin stimulates neurons through PAR1.
Injection of TF‐NH2 into the rat paw stimulated a marked and sustained oedema. An NK1R antagonist and ablation of sensory nerves with capsaicin inhibited oedema by 44% at 1 h and completely by 5 h.
In wild‐type but not PAR1−/− mice, TF‐NH2 stimulated Evans blue extravasation in the bladder, oesophagus, stomach, intestine and pancreas by 2–8 fold. Extravasation in the bladder, oesophagus and stomach was abolished by an NK1R antagonist.
Thus, thrombin cleaves PAR1 on primary spinal afferent neurons to release SP, which activates the NK1R on endothelial cells to stimulate gap formation, extravasation of plasma proteins, and oedema. In intact tissues, neurogenic mechanisms are predominantly responsible for PAR1‐induced oedema.

British Journal of Pharmacology (2001) 133, 975–987; doi:10.1038/sj.bjp.0704152
Further investigations into the endothelium‐dependent hyperpolarizing effects of bradykinin and substance P in porcine coronary artery
Authors: Edwards G , Félétou M , Gardener M J , Glen C D , Richards G R , Vanhoutte P M , Weston A H 
Published: January 2005

In porcine coronary arteries, smooth muscle hyperpolarizations produced by the nitric oxide donor, NOR‐1, and the prostacyclin analogue, iloprost, were compared with those induced by substance P and bradykinin and attributed to the endothelium‐derived hyperpolarizing factor (EDHF).
In the presence of 300 μM L‐nitroarginine and 10 μM indomethacin, iloprost‐induced hyperpolarizations were partially inhibited by 10 μM glibenclamide whereas those to NOR‐1, substance P and bradykinin were unaffected.
Hyperpolarizations produced by maximally‐effective concentrations of NOR‐1 and NS1619 were identical (to −65 mV). They were significantly less than those generated by either substance P or bradykinin (to approximately −80 mV) and were abolished by iberiotoxin 100 nM, a concentration which had essentially no effect on responses to substance P or bradykinin.
Incubation of segments of intact arteries for 16–22 h in bicarbonate‐buffered Krebs solution had little effect on EDHF responses to substance P or bradykinin. In contrast, after incubation for this period of time in HEPES‐buffered Tyrode solution or Krebs containing 10 mM HEPES the EDHF response to substance P was abolished and that to bradykinin was markedly reduced. The residual bradykinin‐induced hyperpolarization following incubation in Tyrode solution was inhibited by iberiotoxin and by 10 μM 17‐octadecynoic acid.
We conclude that substance P activates only the EDHF pathway in the presence of nitric oxide synthase and cyclo‐oxygenase inhibitors. Incubation in HEPES‐buffered Tyrode solution abolishes the EDHF responses to substance P and bradykinin to reveal an additional hyperpolarizing mechanism, associated with the opening of K+ channels, activated only by bradykinin.

British Journal of Pharmacology (2001) 133, 1145–1153; doi:10.1038/sj.bjp.0704157
Phloretin differentially inhibits volume‐sensitive and cyclic AMP‐activated, but not Ca‐activated, Cl− channels
Authors: Fan Hai‐Tian , Morishima Shigeru , Kida Hajime , Okada Yasunobu 
Published: January 2005

Some phenol derivatives are known to block volume‐sensitive Cl− channels. However, effects on the channel of the bisphenol phloretin, which is a known blocker of glucose uniport and anion antiport, have not been examined. In the present study, we investigated the effects of phloretin on volume‐sensitive Cl− channels in comparison with cyclic AMP‐activated CFTR Cl− channels and Ca2+‐activated Cl− channels using the whole‐cell patch‐clamp technique.
Extracellular application of phloretin (over 10 μM) voltage‐independently, and in a concentration‐dependent manner (IC50 ∼30 μM), inhibited the Cl− current activated by a hypotonic challenge in human epithelial T84, Intestine 407 cells and mouse mammary C127/CFTR cells.
In contrast, at 30 μM phloretin failed to inhibit cyclic AMP‐activated Cl− currents in T84 and C127/CFTR cells. Higher concentrations (over 100 μM) of phloretin, however, partially inhibited the CFTR Cl− currents in a voltage‐dependent manner.
At 30 and 300 μM, phloretin showed no inhibitory effect on Ca2+‐dependent Cl− currents induced by ionomycin in T84 cells.
It is concluded that phloretin preferentially blocks volume‐sensitive Cl− channels at low concentrations (below 100 μM) and also inhibits cyclic AMP‐activated Cl− channels at higher concentrations, whereas phloretin does not inhibit Ca2+‐activated Cl− channels in epithelial cells.

British Journal of Pharmacology (2001) 133, 1096–1106; doi:10.1038/sj.bjp.0704159
Direct effect of an acyl‐CoA:cholesterol acyltransferase inhibitor, F‐1394, on atherosclerosis in apolipoprotein E and low density lipoprotein receptor double knockout mice
Authors: Chiwata Tsuyoshi , Aragane Katsumi , Fujinami Koji , Kojima Kazuhiro , Ishibashi Shun , Yamada Nobuhiro , Kusunoki Jun 
Published: January 2005

The acyl‐CoA:cholesterol acyltransferase (ACAT) enzyme is thought to be responsible for foam cell formation and the subsequent progression of atherosclerosis. The apolipoprotein E and low density lipoprotein receptor double knockout (apoE/LDLr‐DKO) mouse is an animal model that develops severe hyperlipidaemia and atherosclerosis.
Here we have examined the effect of oral administration of an ACAT inhibitor, F‐1394, on atherosclerosis in apoE/LDLr‐DKO mice fed a regular chow diet.
In en face analysis, a dose of 10, 30, or 100 mg kg−1 day−1 F‐1394 for 10 weeks reduced the extent of lesions visible in the aorta by 24, 28 and 38%, respectively, as detected by staining with oil red O, without affecting serum cholesterol level in these mice. At the highest dose 100 mg kg−1 day−1 of F‐1394, the reduction was statistically significant.
For quantitative analysis of the cellular and non‐cellular components comprising the lesions at the aortic sinus, the effects of an oral dose of 100 mg kg−1 day−1 F‐1394 for 15 weeks were studied. There was a significant reduction (31.9%) in the oil‐red O‐stained area in cross‐sections of the aortic sinus. In addition, the neointimal area, as well as levels of ACAT‐1 protein tended to be decreased (15.2 and 25.8%, respectively, not significant). However, the areas containing macrophages, smooth muscle cells, and collagen were not affected by F‐1394.
In vitro, F‐1394 attenuated foam cell formation in mouse peritoneal macrophages.
These results indicate that ACAT may be primarily responsible for lipid accumulation in atherosclerotic lesions, and that its inhibition diminishes the lipid deposition via a direct effect on macrophages in the arterial wall.

British Journal of Pharmacology (2001) 133, 1005–1012; doi:10.1038/sj.bjp.0704160
The anti‐migraine 5‐HT1B/1D agonist rizatriptan inhibits neurogenic dural vasodilation in anaesthetized guinea‐pigs
Authors: Williamson David J , Hill Raymond G , Shepheard Sara L , Hargreaves Richard J 
Published: January 2005

These studies investigated the pharmacology of neurogenic dural vasodilation in anaesthetized guinea‐pigs. Following introduction of a closed cranial window the meningeal (dural) blood vessels were visualized using intravital microscopy and the diameter constantly measured using a video dimension analyser.
Dural blood vessels were constricted with endothelin‐1 (3 μg kg−1, i.v.) prior to dilation of the dural blood vessels with calcitonin gene‐related peptide (CGRP; 1 μg kg−1, i.v.) or local electrical stimulation (up to 300 μA) of the dura mater.
In guinea‐pigs pre‐treated with the CGRP receptor antagonist CGRP(8‐37) (0.3 mg kg−1, i.v.) the dilator response to electrical stimulation was inhibited by 85% indicating an important role of CGRP in neurogenic dural vasodilation in this species.
Neurogenic dural vasodilation was also blocked by the 5‐HT1B/1D agonist rizatriptan (100 μg kg−1) with estimated plasma levels commensurate with concentrations required for anti‐migraine efficacy in patients. Rizatriptan did not reverse the dural dilation evoked by CGRP indicating an action on presynaptic receptors located on trigeminal sensory fibres innervating dural blood vessels.
In addition, neurogenic dural vasodilation was also blocked by the selective 5‐HT1D agonist PNU‐142633 (100 μg kg−1) but not by the 5‐HT1F agonist LY334370 (3 mg kg−1) suggesting that rizatriptan blocks neurogenic vasodilation via an action on 5‐HT1D receptors located on perivascular trigeminal nerves to inhibit CGRP release.
This mechanism may underlie one of the anti‐migraine actions of the triptan class exemplified by rizatriptan and suggests that the guinea‐pig is an appropriate species in which to investigate the pharmacology of neurogenic dural vasodilation.

British Journal of Pharmacology (2001) 133, 1029–1034; doi:10.1038/sj.bjp.0704162
Induction of cyclo‐oxygenase‐2 in human endothelial cells by SIN‐1 in the absence of prostaglandin production
Authors: Eligini Sonia , Habib Aïda , Lebret Marilyne , Créminon Christophe , Lévy‐Toledano Sylviane , Maclouf Jacques 
Published: January 2005

Nitric oxide (NO) regulates cyclo‐oxygenase (COX) activity in various cell systems and reports conflict in regard to its stimulatory versus inhibitory role. Incubation of human umbilical vein endothelial cells (HUVEC) with SIN‐1 (3‐morpholinosydnonimine), a donor of NO, resulted in a rapid and dose‐dependent increase in the expression of COX‐2 as analysed by Western and Northern blotting.
Incubation of HUVEC with SIN‐1 and interleukine (IL)‐1α resulted in increased induction of COX‐2 compared with IL‐1α alone and corresponded to an additive effect. The COX‐2 induction was dependent on a de novo synthesis since cycloheximide, an inhibitor of protein synthesis, blocked the enzyme expression. The increase in COX‐2 expression was not accompanied by a corresponding change in prostaglandin (PG) production. However, the COX activity was partially recovered when immunoprecipitated COX‐2 was incubated with arachidonic acid and haematin.
Peroxynitrite, a highly reactive nitrogen molecule derived from the interaction of NO and superoxide anion, significantly increased COX‐2 expression. Under these conditions and within the limit of detection of the antibody, selective antibody for nitrotyrosine failed to detect nitrated COX‐2 in immunoprecipitated COX‐2 when cells where incubated with SIN‐1 or SIN‐1+IL‐1α.
Ro 31‐8220, a specific inhibitor of protein kinase (PK) C, blocked the induction of COX‐2. Also, SB203580, the selective inhibitor of p38 MAP kinase, strongly blocked the induction of COX‐2 by SIN‐1 in the presence or absence of IL‐1α, whereas the MEK‐1 inhibitor, PD 98059, affected it to a lesser extent. These data demonstrate that SIN‐1 induces COX‐2 in HUVEC in the absence of PG formation and suggest a complex regulation of COX‐2 expression and PG formation by NO in endothelial cells.

British Journal of Pharmacology (2001) 133, 1163–1171; doi:10.1038/sj.bjp.0704163