bluuebunny/crossref_metadata_2025_split huggingface dataset:
Anaesthetic agents inhibit gastrin‐stimulated but not basal histamine release from rat stomach ECL cells
Authors: Norlén P , Kitano M , Lindström E , Håkanson R 
Published: January 2005

By mobilizing histamine in response to gastrin, the ECL cells in the oxyntic mucosa play a key role in the control of the parietal cells and hence of gastric acid secretion. General anaesthesia suppresses basal and gastrin‐ and histamine‐stimulated acid secretion. The present study examines if the effect of anaesthesia on basal and gastrin‐stimulated acid secretion is associated with suppressed ECL‐cell histamine secretion.
A microdialysis probe was implanted in the submucosa of the ventral aspect of the acid‐producing part of the stomach (32 rats). Three days later, ECL‐cell histamine mobilization was monitored 2 h before and 4 h after the start of intravenous infusion of gastrin (5 nmol kg−1 h−1). The rats were either conscious or anaesthetized. Four commonly used anaesthetic agents were given 1 h before the start of the experiments by intraperitoneal injection: chloral hydrate (300 mg kg−1), pentobarbitone (40 mg kg−1), urethane (1.5 g kg−1) and a mixture of fluanisone/fentanyl/midazolam (15/0.5/7.5 mg kg−1).
In a parallel series of experiments, basal‐ and gastrin‐induced acid secretion was monitored in six conscious and 25 anaesthetized (see above) chronic gastric fistula rats. All anaesthetic agents lowered gastrin‐stimulated acid secretion; also the basal acid output was reduced (fluanisone/fentanyl/midazolam was an exception).
Anaesthesia reduced gastrin‐stimulated but not basal histamine release by 55–80%. The reduction in gastrin‐induced acid response (70–95%) was strongly correlated to the reduction in gastrin‐induced histamine mobilization. The correlation is in line with the view that the reduced acid response to gastrin reflects impaired histamine mobilization.
Rat stomach ECL cells were purified by counter‐flow elutriation. Gastrin‐evoked histamine mobilization from the isolated ECL cells was determined in the absence or presence of anaesthetic agents in the medium. With the exception of urethane, they inhibited gastrin‐evoked histamine secretion dose‐dependently, indicating a direct effect on the ECL cells.
Anaesthetized rats are widely used to study acid secretion and ECL‐cell histamine release. The present results illustrate the short‐comings of such an approach in that a number of anaesthetic agents were found to impair not only acid secretion but also the secretion of ECL‐cell histamine – some acting in a direct manner.

British Journal of Pharmacology (2000) 130, 725–730; doi:10.1038/sj.bjp.0703347
[3H]‐Trimetazidine mitochondrial binding sites: regulation by cations, effect of trimetazidine derivatives and other agents and interaction with an endogenous substance
Authors: Morin Didier , Sapena Rosa , Elimadi Aziz , Testa Bernard , Labidalle Serge , Le Ridant Alain , Tillement Jean‐Paul 
Published: January 2005

Trimetazidine, an antiischaemic drug, has been shown to restore impaired mitochondrial functions. Specific binding sites for [3H]‐trimetazidine have been previously detected in liver mitochondria. In the present study we confirm this observation and provide additional evidence for the involvement of these sites in the pharmacological effects of the drug.
Inhibition experiments using a series of trimetazidine derivatives revealed the presence of three classes of binding sites. An N‐benzyl substituted analogue of trimetazidine exhibited a very high affinity (Ki=7 nM) for one of these classes of sites.
Compounds from different pharmacological classes were evaluated for their ability to inhibit [3H]‐trimetazidine binding. Among the drugs tested pentazocine, ifenprodil, opipramol, perphenazine, haloperidol, and to a lower extent prenylamine, carbetapentane and dextromethorphan competed with high affinity, suggesting a similarity of high affinity [3H]‐trimetazidine sites with sigma receptors.
[3H]‐Trimetazidine binding was modulated by pH. Neutral trimetazidine had about 10 fold higher affinity than protonated trimetazidine for its mitochondrial binding sites. Various cations also affected [3H]‐trimetazidine binding. Ca2+ was the most potent inhibitor and totally suppressed the binding of [3H]‐trimetazidine to the sites of medium affinity.
An endogenous cytosolic ligand was able to displace [3H]‐trimetazidine from its binding sites. Its activity was not affected by boiling for 15 min, suggesting a non‐protein compound.
These data suggest that mitochondrial [3H]‐trimetazidine binding sites could have a physiological relevance and be involved in the antiischaemic effects of the drug.

British Journal of Pharmacology (2000) 130, 655–663; doi:10.1038/sj.bjp.0703348
Evidence that 2‐methylthioATP and 2‐methylthioADP are both agonists at the rat hepatocyte P2Y1receptor
Authors: Dixon C Jane 
Published: January 2005

In the absence of selective antagonists, pharmacological characterization of P2Y receptor subtypes has relied heavily upon their distinct agonist profiles. 2‐methylthioADP (2‐MeSADP) is a selective agonist for the P2Y1receptor. The agonist action of 2‐MeSATP at the P2Y1receptor has recently been questioned.The effects of both 2‐MeSADP and 2‐MeSATP have been studied on rat hepatocytes injected with the bioluminescent Ca2+indicator, aequorin. Single hepatocytes generate series of repetitive transients in cytosolic free calcium concentration ([Ca2+]i) when stimulated with agonists acting through the phosphoinositide signalling pathway.The transients induced by 2‐MeSADP and 2‐MeSATP in the same cell were indistinguishable, indicating that they act at a common receptor. In contrast the transients evoked by ATP and UTP had very different profiles. Treatment of 2‐MeSATP with an ATP‐regenerating system to remove contaminating 2‐MeSADP did not abolish its agonist activity.Application of the P2Y1antagonist, adenosine‐3′‐phosphate‐5′‐phosphate (A3P5P) inhibited the transients induced by both 2‐MeSADP and 2‐MeSATP. In contrast the transients induced by ATP and UTP were enhanced by the addition of A3P5P.These results indicate that both 2‐MeSADP and 2‐MeSATP are agonists at the rat hepatocyte P2Y1receptor.British Journal of Pharmacology(2000)130, 664–668; doi:10.1038/sj.bjp.0703350
Mechanisms underlying the attenuation of endothelium‐dependent vasodilatation in the mesenteric arterial bed of the streptozotocin‐induced diabetic rat
Authors: Makino Ayako , Ohuchi Kunihiro , Kamata Katsuo 
Published: January 2005

Experiments were designed to investigate the mechanisms underlying the diabetes‐related impairment of the vasodilatations of the perfused mesenteric arterial bed induced by acetylcholine (ACh) and K+.
In streptozotocin (STZ)‐diabetic rats, the ACh‐induced endothelium‐dependent vasodilatation was attenuated. The dose‐response curves for ACh in control and diabetic rats were each shifted to the right by NG‐nitro‐L‐arginine (L‐NOARG) and by isotonic high K+ (60 mM). The ACh dose‐response curves under isotonic high K+ were not different between control and diabetic rats.
We also examined the vasodilatation induced by K+, which is a putative endothelium‐derived hyperpolarizing factor (EDHF). The mesenteric vasodilatation induced by a single administration of K+ was greatly impaired in STZ‐induced diabetic rats. Treatment with charybdotoxin plus apamin abolished the ACh‐induced vasodilatation but enhanced the K+‐induced response in controls and diabetic rats. After pretreatment with ouabain plus BaCl2, the ACh‐induced vasodilatation was significantly impaired and the K+‐induced relaxation was abolished in both control and diabetic rats.
The impairment of the endothelium‐dependent vasodilatation of the mesenteric arterial bed seen in STZ‐induced diabetic rats may be largely due to a defective vascular response to EDHF. It is further suggested that K+ is one of the endothelium‐derived hyperpolarizing factors and that the vasodilatation response to K+ is impaired in the mesenteric arterial bed from diabetic rats.

British Journal of Pharmacology (2000) 130, 549–556; doi:10.1038/sj.bjp.0703354
Exploration of the ligand binding site of the human 5‐HT4 receptor by site‐directed mutagenesis and molecular modeling
Authors: Mialet Jeanne , Dahmoune Yamina , Lezoualc'h Frank , Berque‐Bestel Isabelle , Eftekhari Pierre , Hoebeke Johan , Sicsic Sames , Langlois Michel , Fischmeister Rodolphe 
Published: January 2005

Among the five human 5‐HT4 (h5‐HT4) receptor isoforms, the h5‐HT4(a) receptor was studied with a particular emphasis on the molecular interactions involved in ligand binding. For this purpose, we used site‐directed mutagenesis of the transmembrane domain. Twelve mutants were constructed with a special focus on the residue P4.53 of helix IV which substitutes in h5‐HT4 receptors the highly conserved S residue among the rhodopsin family receptors. The mutated receptors were transiently expressed in COS‐7 cells.
Ligand binding or competition studies with two h5‐HT4 receptor agonists, serotonin and ML10302 and two h5‐HT4 receptor antagonists, [3H]‐GR113808 and ML10375 were performed on wild type and mutant receptors. Functional activity of the receptors was evaluated by measuring the ability of serotonin to stimulate adenylyl cyclase.
Ligand binding experiments revealed that [3H]‐GR113808 did not bind to mutants P4.53A, S5.43A, F6.51A, Y7.43A and to double mutant F6.52V/N6.55L. On the other hand mutations D3.32N, S5.43A and Y7.43A appeared to promote a dramatic decrease of h5‐HT4(a) receptor functional activity. From these studies, S5.43 and Y7.43 clearly emerged as common anchoring sites to antagonist [3H]‐GR113808 and to serotonin.
According to these results, we propose ligand‐receptor complex models with serotonin and [3H]‐GR113808. For serotonin, three interaction points were selected including ionic interaction with D3.32, a stabilizing interaction of this ion pair by Y7.43 and a hydrogen bond with S5.43. [3H]‐GR113808 was also docked, based on the same type of interactions with S5.43 and D3.32: the proposed model suggested a possible role of P4.53 in helix IV structure allowing the involvement of a close hydrophobic residue, W4.50, in a hydrophobic pocket for hydrophobic interactions with the indole ring of [3H]‐GR113808.

British Journal of Pharmacology (2000) 130, 527–538; doi:10.1038/sj.bjp.0703356
Tumour necrosis factor‐α‐ and interleukin‐1β‐stimulated cell proliferation through activation of mitogen‐activated protein kinase in canine tracheal smooth muscle cells
Authors: Yang Chuen‐Mao , Luo Shue‐Fen , Wang Chuan‐Chwan , Chiu Chi‐Tso , Chien Chin‐Sung , Lin Chih‐Chung , Hsiao Li‐Der 
Published: January 2005

The elevated levels of inflammatory cytokines such as tumour necrosis factor‐α (TNF‐α) and interleukin‐1β (IL‐1β) have been found in the fluid of airways in symptomatic asthmatics. These cytokines have been considered as mitogens to stimulate cell proliferation in tracheal smooth muscle cells (TSMCs). We therefore investigated the effects of TNF‐α and IL‐1β on cell proliferation and activation of p42/p44 mitogen‐activated protein kinase (MAPK) in these cells.
TNF‐α and IL‐1β induced [3H]‐thymidine incorporation in a time‐ and concentration‐dependent manner. The maximal stimulation of [3H]‐thymidine incorporation induced by TNF‐α and IL‐1β was seen 12 h after incubation with these cytokines.
In response to TNF‐α and IL‐1β, p42/p44 MAPK was activated with a concentration‐dependent manner in TSMCs. Pretreatment of TSMCs with pertussis toxin did not change DNA synthesis and phosphorylation of MAPK induced by TNF‐α and IL‐1β. These responses were attenuated by a tyrosine kinase inhibitor herbimycin, a phosphatidyl choline (PC)‐phospholipase C (PLC) inhibitor D609, a phosphatidyl inositide (PI)‐PLC inhibitor U73122, a protein kinase C inhibitor staurosporine, and removal of Ca2+ by addition of BAPTA/AM plus EGTA.
TNF‐α‐ and IL‐1β‐induced [3H]‐thymidine incorporation and phosphorylation of p42/p44 MAPK was completely inhibited by PD98059 (an inhibitor of MEK1/2), indicating that activation of MEK1/2 was required for these responses.
These results suggest that the mitogenic effects of TNF‐α and IL‐1β were mediated through the activation of MEK1/2 and p42/p44 MAPK pathway. TNF‐α‐ and IL‐1β‐mediated responses were modulated by PLC, Ca2+, PKC, and tyrosine kinase associated with cell proliferation in TSMCs.

British Journal of Pharmacology (2000) 130, 891–899; doi:10.1038/sj.bjp.0703359
Evidence for activation of the tissue kallikrein‐kinin system in nociceptive transmission and inflammatory responses of mice using a specific enzyme inhibitor
Authors: Emim José A da S , Souccar Caden , Castro Maria S de A , Godinho Rosely O , Cezari Maria H S , Juliano Luiz , Lapa Antonio J 
Published: January 2005

The pharmacological activity of phenylacetyl‐Phe‐Ser‐Arg‐N‐(2,4‐dinitrophenyl)‐ethylenediamine (TKI), a tissue kallikrein specific inhibitor, was assessed using models of nociception and inflammation in mice.
Injection of TKI (13.6–136 μmol kg−1, i.p. or 41–410 μmol kg−1, s.c.) produced a dose‐related inhibition of the acetic acid‐induced writhes (by 37 to 85% or 34 to 80%, respectively). The antinociceptive activity of TKI (41 μmol kg−1, i.p.) was maximal after 30 min injection and lasted for 120 min. The effect was unaltered by pretreatment with naloxone (8.2 μmol kg−1, s.c.) or bilateral adrenalectomy.
TKI (41 and 136 μmol kg−1, i.p.) produced a dose‐related decrease of the late phase of formalin‐induced nociception by 79 and 98%, respectively. At 136 μmol kg−1, i.p., TKI also shortened the duration of paw licking in the early phase by 69%. TKI (41 and 136 μmol kg−1, i.p.) also reduced the capsaicin‐induced nociceptive response (by 51 to 79%).
TKI (41 μmol kg−1, i.p. or 410 μmol kg−1, s.c.) reduced the oedematogenic response, from the second to the fifth hour after carrageenin injection by 36 to 30% or by 47 to 39%, respectively.
Pretreatment with TKI (41 μmol kg−1, i.p.) reduced the capsaicin‐induced neurogenic inflammation in the mouse ear by 54%.
It is concluded that TKI presents antinociceptive and antiinflammatory activities mediated by inhibition of kinin formation by tissue kallikrein in mice. The results also indicate that the tissue kallikrein‐dependent pathway contributes to kinin generation in nociceptive and inflammatory processes in mice.

British Journal of Pharmacology (2000) 130, 1099–1107; doi:10.1038/sj.bjp.0703362
Multiple action sites of flufenamate on ion transport across the rat distal colon
Authors: Schultheiss G , Frings M , Hollingshaus G , Diener M 
Published: January 2005

The antisecretory effects of flufenamate in the rat distal colon were investigated with the Ussing‐chamber and the patch‐clamp method as well as by measurements of the intracellular Ca2+ concentration using fura‐2‐loaded isolated crypts.
Flufenamate (5•10−4 mol l−1) suppressed the short‐circuit current (Isc) induced by carbachol (5•10−5 mol l−1), forskolin (5•10−6 mol l−1) and the Isc induced by the membrane‐permeable analogue of cyclic AMP, CPT–cyclic AMP (10−4 mol l−1).
Indomethacin (10−6–10−4 mol l−1) did not mimic the effect of flufenamate, indicating that the antisecretory effect of flufenamate is not related to the inhibition of the cyclo‐oxygenase.
When the basolateral membrane was depolarized by a high K+ concentration and a Cl− current was induced by a mucosally directed Cl− gradient, the forskolin‐stimulated Cl− current was blocked by flufenamate, indicating an inhibition of the cyclic AMP‐stimulated apical Cl− conductance.
When the apical membrane was permeabilized by the ionophore, nystatin, flufenamate decreased the basolateral K+ conductance and inhibited the Na+–K+‐ATPase.
Patch‐clamp experiments revealed a variable effect of flufenamate on membrane currents. In seven out of 11 crypt cells the drug induced an increase of the K+ current, whereas in the remaining four cells an inhibition was observed.
Experiments with fura‐2‐loaded isolated crypts indicated that flufenamate increased the basal as well as the carbachol‐stimulated intracellular Ca2+ concentration.
These results demonstrate that flufenamate possesses multiple action sites in the rat colon: The apical Cl− conductance, basolateral K+ conductances and the Na+–K+‐ATPase.

British Journal of Pharmacology (2000) 130, 875–885; doi:10.1038/sj.bjp.0703363
Contribution of β‐adrenoceptor subtypes to relaxation of colon and oesophagus and pacemaker activity of ureter in wildtype and β3‐adrenoceptor knockout mice
Authors: Oostendorp Jaap , Preitner Frédéric , Moffatt James , Jimenez Maria , Giacobino Jean Paul , Molenaar Peter , Kaumann Alberto Julio 
Published: January 2005

The smooth muscle relaxant responses to the mixed β3‐, putative β4‐adrenoceptor agonist, (−)‐CGP 12177 in rat colon are partially resistant to blockade by the β3‐adrenoceptor antagonist SR59230A suggesting involvement of β3‐ and putative β4‐adrenoceptors. We now investigated the function of the putative β4‐adrenoceptor and other β‐adrenoceptor subtypes in the colon, oesophagus and ureter of wildtype (WT) and β3‐adrenoceptor knockout (β3KO) mice.
(−)‐Noradrenaline and (−)‐adrenaline relaxed KCl (30 mM)‐precontracted colon mostly through β1‐and β3‐adrenoceptors to a similar extent and to a minor extent through β2‐adrenoceptors. In colon from β3KO mice, (−)‐noradrenaline was as potent as in WT mice but the effects were mediated entirely through β1‐adrenoceptors. (−)‐CGP 12177 relaxed colon from β3KO mice with 2 fold greater potency than in WT mice. The maintenance of potency for (−)‐noradrenaline and increase for (−)‐CGP 12177 indicate compensatory increases in β1‐ and putative β4‐adrenoceptor function in β3KO mice.
In oesophagi precontracted with 1 μM carbachol, (−)‐noradrenaline caused relaxation mainly through β1‐and β3‐adrenoceptors. (−)‐CGP 12177 (2 μM) relaxed oesophagi from WT by 61.4±5.1% and β3KO by 67.3±10.1% of the (−)‐isoprenaline‐evoked relaxation, consistent with mediation through putative β4‐adrenoceptors.
In ureter, (−)‐CGP 12177 (2 μM) reduced pacemaker activity by 31.1±2.3% in WT and 31.3±7.5% in β3KO, consistent with mediation through putative β4‐adrenoceptors.
Relaxation of mouse colon and oesophagus by catecholamines are mediated through β1‐ and β3‐adrenoceptors in WT. The putative β4‐adrenoceptor, which presumably is an atypical state of the β1‐adrenoceptor, mediates the effects of (−)‐CGP 12177 in colon, oesophagus and ureter.

British Journal of Pharmacology (2000) 130, 747–758; doi:10.1038/sj.bjp.0703365
JTV‐519, a novel cardioprotective agent, improves the contractile recovery after ischaemia‐reperfusion in coronary perfused guinea‐pig ventricular muscles
Authors: Ito Ken‐ichiro , Shigematsu Sakuji , Sato Toshiaki , Abe Takako , Li Yulong , Arita Makoto 
Published: January 2005

A newly synthesized benzothiazepine derivative, JTV‐519 (JT) has been reported to be cardioprotective. However, the precise mechanism underlying the cardioprotective effect of this drug is unknown.
Coronary‐perfused guinea‐pig ventricular muscles were subjected to 20‐min no‐flow ischaemia followed by 60‐min reperfusion (I/R). I/R significantly decreased the contraction in untreated preparations (control group, 34±4% of baseline value, n=6). Brief administration of JT (1.0 μM) prior to ischaemia significantly improved the postischaemic contractile recovery (63±5% of baseline value, n=4), as compared to the control group.
JT (1.0 μM) slightly prolonged action potential duration before ischaemia and induced conduction disturbance (2 : 1 block) after the initiation of ischaemia.
The cardioprotective effect of JT was antagonized by chelerythrine (CH, 5.0 μM), an inhibitor of protein kinase C (PKC) or by 5‐hydroxydecanoic acid (5‐HD, 400 μM), an inhibitor of mitochondrial ATP‐sensitive K+ (KATP) channels.
These results suggest that the protective effect of JT is due to the opening of mitochondrial KATP channels, which, in turn, is linked to PKC activation.

British Journal of Pharmacology (2000) 130, 767–776; doi:10.1038/sj.bjp.0703373
Role of loop D of the α7 nicotinic acetylcholine receptor in its interaction with the insecticide imidacloprid and related neonicotinoids
Authors: Matsuda Kazuhiko , Shimomura Masaru , Kondo Yumi , Ihara Makoto , Hashigami Kaori , Yoshida Naofumi , Raymond Valérie , Mongan Nigel P , Freeman John C , Komai Koichiro , Sattelle David B 
Published: January 2005

The nitroguanidine insecticide imidacloprid along with a second generation of related compounds including nitenpyram, all nicotinic acetylcholine (ACh) receptor ligands, are used increasingly in many countries. Site‐directed mutagenesis and heterologous expression in Xenopus laevis oocytes have been deployed to investigate mutants (G189D and G189E) of the chicken α7 homomer‐forming nicotinic receptor subunit which are predicted to enhance the negative charge at the negative subsite (loop D) of the ACh binding site.
Xenopus oocytes expressing wild‐type α7 nicotinic receptors respond to imidacloprid with rapid inward currents. Imidacloprid and nitenpyram are partial agonists, whereas ACh, (−)‐nicotine and (+)‐epibatidine are full agonists.
Compared to wild‐type α7, the mutant G189D and G189E receptors are much less sensitive to the insecticides, whereas their sensitivity to (−)‐nicotine, ACh and (+)‐epibatidine is only slightly reduced. In contrast, G189N and G189Q mutants are sensitive not only to ACh, (−)‐nicotine and (+)‐epibatidine, but also to the two insecticides. Thus reduction of the insecticide‐sensitivity by the mutations G189D and G189E are attributed to an increase in negativity of loop D. Desnitro‐imidacloprid (DN‐IMI), an imidacloprid derivative lacking the nitro group is a potent agonist on the G189D and G189E mutants suggesting an important role of loop D in nicotinic receptor interactions with the nitro group of nitroguanidine insecticides.

British Journal of Pharmacology (2000) 130, 981–986; doi:10.1038/sj.bjp.0703374
Electrophysiological effects of endothelin‐1 and their relationship to contraction in rat renal arterial smooth muscle
Authors: Betts Luisa C , Kozlowski Roland Z 
Published: January 2005

The electophysiological effects of endothelin‐1 (ET‐1) and their relationship to contraction remain unclear in the renal circulation. Using endotheliumdenuded arteries from the main branch of the renal artery proximal to the kidney of the rat, we have examined its effects on tension and conducted parallel patch‐clamp measurements using freshly isolated smooth muscle cells from this tissue.
Pharmacological experiments revealed that ET‐1 produced constriction of renal arteries dependent on the influx of extracellular Ca2+, mediated solely through ETA receptor stimulation.
Current‐clamp experiments revealed that renal arterial myocytes had a resting membrane potential of ∼32 mV, with the majority of cells exhibiting spontaneous transient hyperpolarizations (STHPs). Application of ET‐1 produced depolarization and in those cells exhibiting STHPs, either caused their inhibition or made them occur regularly.
Under voltage‐clamp conditions cells were observed to exhibit spontaneous transient outward currents (STOCs) inhibited by iberiotoxin. Application of voltage‐ramps revealed an outward current activated at ∼−30 mV, sensitive to both 4‐AP and TEA. Taken together these results suggest that renal arterial myocytes possess both delayed rectifying K+ (KV) and Ca2+‐activated K+ (BKCa) channels.
Under voltage‐clamp, ET‐1 attenuated the outward current and reduced the magnitude and incidence of STOCs: effects mediated solely as a consequence of ETA receptor stimulation.
Thus, in conclusion, activation of ETA receptors by ET‐1 causes inhibition of KV and BKCa channel activity, which could promote and/or maintain membrane depolarization. This effect is likely to favour L‐type Ca2+ channel activity providing an influx pathway for extracellular Ca2+ essential for contraction.

British Journal of Pharmacology (2000) 130, 787–796; doi:10.1038/sj.bjp.0703377