bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inhibition of acetylcholine‐activated K+ currents by U73122 is mediated by the inhibition of PIP2‐channel interaction
Authors: Cho Hana , Youm Jae Boum , Ryu Shin Young , Earm Yung E , Ho Won‐Kyung 
Published: January 2005

We have investigated the effect of U73122, a specific inhibitor of phospholipase C (PLC), on acetylcholine‐activated K+ currents (IKACh) in mouse atrial myocytes.
In perforated patch clamp mode, IKACh was activated by 10 μM acetylcholine. When atrial myocytes were pretreated with U73122 or U73343, IKACh was inhibited dose‐dependently (half‐maximal inhibition at 0.12±0.0085 and 0.16±0.0176 μM, respectively). The current‐voltage relationships for IKACh in the absence and in the presence of U73122 showed that the inhibition occurred uniformly from −120 to +40 mV, indicating a voltage‐independent inhibition.
When U73122 was applied after IKACh reached steady‐state, a gradual decrease in IKACh was observed. The time course of the current decrease was well fitted to a single exponential, and the rate constant was proportional to the concentration of U73122.
When KACh channels were directly activated by adding 1 mM GTPγS to the bath solution in inside‐out patches, U73122 (1 μM) decreased the open probability significantly without change in mean open time. When KACh channels were activated independently of G‐protein activation by 20 mM Na+, open probability was also inhibited by U73122.
Voltage‐activated K+ currents and inward rectifying K+ currents were not affected by U73122.
These findings show that inhibition by U73122 and U73343 of KACh channels occurs at a level downstream of the action of Gβγ or Na+ on channel activation. The interference with phosphatidylinositol 4,5‐bisphosphate (PIP2)‐channel interaction can be suggested as a most plausible mechanism.

British Journal of Pharmacology (2001) 134, 1066–1072; doi:10.1038/sj.bjp.0704347
Cellular target of voltage and calcium‐dependent K+ channel blockers involved in EDHF‐mediated responses in rat superior mesenteric artery
Authors: Ghisdal Philippe , Morel Nicole 
Published: January 2005

We have investigated the cellular target of K+ channel blockers responsible for the inhibition of the EDHF‐mediated relaxation in the rat mesenteric artery by studying their effects on tension, smooth muscle cell (SMC) membrane potential and endothelial cell Ca2+ signal ([Ca2+]endo).
In arteries contracted with prostaglandin F2α (2.5 – 10 μM), relaxation evoked by ACh (0.01 – 3 μM) was abolished by a combination of charybdotoxin (ChTX, 0.1 μM) plus apamin (Apa, 0.1 μM) and was inhibited by 68±6% (n=6) by 4‐aminopyridine (4‐AP, 5 mM).
ACh (0.001 – 3 μM) increased [Ca2+]endo and hyperpolarized SMCs with the same potency, the pD2 values were equal to 7.2±0.08 (n=4) and 7.2±0.07 (n=9), respectively. SMCs hyperpolarization to ACh (1 μM) was abolished by high K+ solution or by ChTX/Apa. It was decreased by 66±5% (n=6) by 4‐AP.
The increase in [Ca2+]endo evoked by ACh (1 μM) was insensitive to ChTX/Apa but was depressed by 58±16% (n=6) and 27±4% (n=7) by raising external K+ concentration and by 4‐AP, respectively.
The effect of 4‐AP on [Ca2+]endo was not affected by increasing external K+ concentration. In Ca‐free/EGTA solution, the transient increase in [Ca2+]endo evoked by ACh (1 μM) was abolished by thapsigargin (1 μM) and was decreased by 75±7% (n=5) by 4‐AP.
These results show that inhibition of EDHF‐evoked responses by 4‐AP may be attributed to a decrease in the Ca2+ release activated by ACh in endothelial cells. The abolition of SMCs hyperpolarization to ACh by ChTX/Apa is not related to an interaction with the [Ca2+]endo.

British Journal of Pharmacology (2001) 134, 1021–1028; doi:10.1038/sj.bjp.0704348
α1‐Adrenoceptor subtypes in the mouse mesenteric artery and abdominal aorta
Authors: Yamamoto Yoshihisa , Koike Katsuo 
Published: January 2005

Subtypes of α1‐adrenoceptor‐mediated contractions to noradrenaline in mouse mesenteric artery and abdominal aorta were examined.
In mesenteric artery, BMY7378, 5‐methylurapidil, WB4101 and prazosin were inhibited contraction to noradrenaline The good correlation for pA2 values of antagonists in native α1D‐ (rat thoracic aorta) adrenoceptor subtype and pKi values in rat cloned α1d‐adrenoceptor with the pA2 values estimated in the mouse mesenteric artery was obtained. However, the pA2 value for BMY7378 is significantly lower than the accepted value against the α1D‐adrenoceptor subtype.
In the abdominal aorta, it was obtained the regional difference for the sensitivity for noradrenaline.
In the upper abdominal aorta, the good correlation for the pA2 values of the antagonists in the native α1D‐adrenoceptor subtype and pKi values in the cloned α1d‐adrenoceptor with the pA2 values estimated in the upper abdominal aorta was obtained, and regression line was close to the line of identity.
In the lower abdominal aorta, the good correlation for the reported pKi values in the cloned α1a‐adrenoceptor subtype with the pA2 values estimated in the mouse lower abdominal aorta was obtained, and regression line was close to the line of identity.
In conclusion, the present functional data in the mouse suggest that (1) α1D‐like adrenoceptors are present in the mesenteric artery, (2) there is the regional difference for the sensitivity for noradrenaline in the abdominal aorta and (3) noradrenaline evokes the contraction mediated through α1D‐adrenoceptor in the upper abdominal aorta, whereas there is α1A‐adrenoceptor‐mediated contraction in the lower abdominal aorta.

British Journal of Pharmacology (2001) 134, 1045–1054; doi:10.1038/sj.bjp.0704350
Pharmacological and biochemical characterization of adenosine receptors in the human malignant melanoma A375 cell line
Authors: Merighi Stefania , Varani Katia , Gessi Stefania , Cattabriga Elena , Iannotta Valeria , Ulouglu Canan , Leung Edward , Borea Pier Andrea 
Published: January 2005

The present work characterizes, from a pharmacological and biochemical point of view, adenosine receptors in the human malignant melanoma A375 cell line.
Adenosine receptors were detected by RT – PCR experiments. A1 receptors were characterized using [3H]‐DPCPX binding with a KD of 1.9±0.2 nM and Bmax of 23±7 fmol mg−1 of protein. A2A receptors were studied with [3H]‐SCH 58261 binding and revealed a KD of 5.1±0.2 nM and a Bmax of 220±7 fmol mg−1 of protein. A3 receptors were studied with the new A3 adenosine receptor antagonist [3H]‐MRE 3008F20, the only A3 selective radioligand currently available. Saturation experiments revealed a single high affinity binding site with KD of 3.3±0.7 nM and Bmax of 291±50 fmol mg−1 of protein.
The pharmacological profile of radioligand binding on A375 cells was established using typical adenosine ligands which displayed a rank order of potency typical of the different adenosine receptor subtype.
Thermodynamic data indicated that radioligand binding to adenosine receptor subtypes in A375 cells was entropy‐ and enthalpy‐driven.
In functional assays the high affinity A2A agonists HE‐NECA, CGS 21680 and A2A – A2B agonist NECA were able to increase cyclic AMP accumulation in A375 cells whereas A3 agonists Cl‐IB‐MECA, IB‐MECA and NECA were able to stimulate Ca2+ mobilization.
In conclusion, all these data indicate, for the first time, that adenosine receptors with a pharmacological and biochemical profile typical of the A1, A2A, A2B and A3 receptor subtype are present on A375 melanoma cell line.

British Journal of Pharmacology (2001) 134, 1215–1226; doi:10.1038/sj.bjp.0704352
Influence of membrane cholesterol on modulation of the GABAA receptor by neuroactive steroids and other potentiators
Authors: Sooksawate T , Simmonds M A 
Published: January 2005

The influence of membrane cholesterol on some pharmacological properties of the GABAA receptor was investigated in acutely dissociated rat hippocampal neurones with whole cell patch clamp recording. The cholesterol levels were varied between 56% and 235% control using methyl‐β‐cyclodextrin as the cholesterol carrier.
Enrichment of neurones with cholesterol increased the effects of the non‐steroidal GABA potentiators propofol, flunitrazepam and pentobarbitone. A similar result was obtained after pre‐incubation of neurones with epicholesterol, the 3α‐hydroxy isomer of cholesterol.
In contrast, the effects of the steroidal GABA potentiators pregnanolone and alfaxalone were reduced by cholesterol enrichment, but not by epicholesterol. Depletion of membrane cholesterol increased the potentiation of GABA by pregnanolone and alfaxalone but did not affect the non‐steroidal potentiators.
The steroidal antagonist of GABA, pregnenolone sulphate, reduced the maximum response to GABA. This effect, also, was diminished in cholesterol‐enriched neurones and enhanced in cholesterol‐depleted neurones.
The effects of the cholesterol manipulations that were selective for the steroidal modulators of GABA are suggested to arise from direct interactions between membrane cholesterol and the GABAA receptor. The separate effects on the non‐steroidal potentiators of GABA of cholesterol‐enrichment or addition of epicholesterol to the neurones are suggested to be due to changes in membrane fluidity.
In view of the likely physiological modulation of GABAA receptors by endogenous neuroactive steroids and evidence of the in vivo lability of membrane cholesterol, the present observations may have physiological as well as pharmacological relevance.

British Journal of Pharmacology (2001) 134, 1303–1311; doi:10.1038/sj.bjp.0704360
Characterization of two Bunodosoma granulifera toxins active on cardiac sodium channels
Authors: Goudet Cyril , Ferrer Tania , Galàn Loipa , Artiles Adriana , Batista Cesar F V , Possani Lourival D , Alvarez Julio , Aneiros Abel , Tytgat Jan 
Published: January 2005

Two sodium channel toxins, BgII and BgIII, have been isolated and purified from the sea anemone Bunodosoma granulifera. Combining different techniques, we have investigated the electrophysiological properties of these toxins.
We examined the effect of BgII and BgIII on rat ventricular strips. These toxins prolong action potentials with EC50 values of 60 and 660 nM and modify the resting potentials.
The effect on Na+ currents in rat cardiomyocytes was studied using the patch‐clamp technique. BgII and BgIII slow the rapid inactivation process and increase the current density with EC50 values of 58 and 78 nM, respectively.
On the cloned hH1 cardiac Na+ channel expressed in Xenopus laevis oocytes, BgII and BgIII slow the inactivation process of Na+ currents (respective EC50 values of 0.38 and 7.8 μM), shift the steady‐state activation and inactivation parameters to more positive potentials and the reversal potential to more negative potentials.
The amino acid sequences of these toxins are almost identical except for an asparagine at position 16 in BgII which is replaced by an aspartic acid in BgIII. In all experiments, BgII was more potent than BgIII suggesting that this conservative residue is important for the toxicity of sea anemone toxins.
We conclude that BgII and BgIII, generally known as neurotoxins, are also cardiotoxic and combine the classical effects of sea anemone Na+ channels toxins (slowing of inactivation kinetics, shift of steady‐state activation and inactivation parameters) with a striking decrease on the ionic selectivity of Na+ channels.

British Journal of Pharmacology (2001) 134, 1195–1206; doi:10.1038/sj.bjp.0704361
The effects of dentate granule cell destruction on behavioural activity and Fos protein expression induced by systemic methamphetamine in rats
Authors: Tani Kunihiko , Iyo Masaomi , Matsumoto Hideo , Kawai Masayoshi , Suzuki Katsuaki , Iwata Yasuhide , Won Taketoshi , Tsukamoto Toshio , Sekine Yoshimoto , Sakanoue Masatsuna , Hashimoto Kenji , Ohashi Yutaka , Takei Nori , Mori Norio 
Published: January 2005

We destroyed dentate granule cells unilaterally or bilaterally by means of intrahippocampal injection of colchicine in rats. Subsequently, we observed behavioural changes following the intraperitoneal injection of 2 mg kg−1 methamphetamine or saline, in addition to quantitatively assessing Fos protein expression in several brain regions, including the medial prefrontal cortex, cingulate cortex, piriform cortex, dorsal striatum, and nucleus accumbens.
Bilaterally lesioned animals, when administered saline, showed a marked increase in locomotor activity compared with those of non‐lesioned animals. With respect to the methamphetamine response, bilateral destruction resulted in a marked enhancement of locomotor activity, while the unilateral destruction led to a marked increase in rotation predominantly contralateral to the lesioned side, with no identifiable change in locomotor activity.
Bilaterally lesioned animals, when administered saline and having undergone an immunohistological examination, showed a marked increase in Fos expression in both sides of the nucleus accumbens. Bilaterally lesioned animals administered methamphetamine showed a marked increase in Fos expression in the right and left sides of all regions tested. Unilaterally lesioned animals administered methamphetamine showed a significant and bilateral enhancement in Fos expression in the medial prefrontal and cingulate cortices, and a marked and unilateral (ipsilateral to the lesioned side) enhancement of Fos protein in the piriform cortex, dorsal striatum, and nucleus accumbens.
The present findings suggest that dentate granule cells regulate methamphetamine‐associated behavioural changes through the function of widespread areas of the brain, mostly the nucleus accumbens.

British Journal of Pharmacology (2001) 134, 1411–1418; doi:10.1038/sj.bjp.0704370
Analysis of the temporal expression of chemokines and chemokine receptors during experimental granulomatous inflammation: role and expression of MIP‐1α and MCP‐1
Authors: Carollo Maria , Hogaboam Cory M , Kunkel Stephen L , Delaney Stephen , Christie Mark I , Perretti Mauro 
Published: January 2005

Chemokine expression and function was monitored in an experimental model of granulomatous tissue formation after injection of croton oil in complete Freund's adjuvant (CO/CFA) into mouse dorsal air‐pouches up to 28 days.
In the first week, mast cell degranulation and leukocyte influx (mononuclear cell, MNC, and polymorphonuclear cell, PMN) were associated with CXCR2, KC and macrophage inflammatory protein (MIP)‐2 mRNA expression, as determined by TaqMan® reverse transcriptase‐polymerase chain reaction. KC (∼400 pg mg protein−1, n=12) and MIP‐2 (∼800 pg mg protein−1, n=12) proteins peaked at day 7, together with myeloperoxidase (MPO) activity. Highest MIP‐1α (>1 ng mg protein−1, n=12) levels were measured at day 3.
After day 7, a gradual increase in CCR2 and CCR5 mRNA, monocyte chemoattractant protein (MCP)‐1 mRNA and protein expression was measured. MCP‐1 protein peaked at day 21 (∼150 pg mg protein−1, n=12) and was predominantly expressed by mast cells. A gradual increase in N‐acetyl‐β‐D‐glucosaminidase (NAG) activity (maximal at 28 days) was also measured.
An antiserum against MIP‐1α did not modify the inflammatory response measured at day 7 (except for a 50% reduction in MIP‐1α levels), but provoked a significant increase in MPO, NAG and MCP‐1 levels as measured at day 21 (n=6, P<0.05). An antiserum to MCP‐1 reduced NAG activity at day 21 but increased MPO activity values (n=8, P<0.05).
In conclusion, we have shown that CO/CFA initiates a complex inflammatory reaction in which initial expression of MIP‐1α serves a protective role whereas delayed expression of MCP‐1 seems to have a genuine pro‐inflammatory role.

British Journal of Pharmacology (2001) 134, 1166–1179; doi:10.1038/sj.bjp.0704371
Anandamide administration into the ventromedial hypothalamus stimulates appetite in rats
Authors: Jamshidi Nazila , Taylor David A 
Published: January 2005

This investigation reports the possible role of the endocannabinoid anandamide in modulating appetitive behaviour. Given that cannabinoids have been used clinically to stimulate appetite in HIV and cancer chemotherapy patients, there has been a renewed interest in the involvement of cannabinoids in appetite modulation. This is the first report on the administration of anandamide into the ventromedial hypothalamus. Pre‐satiated rats received an intrahypothalamic injection of anandamide (50 ng 0.5 μl−1) followed by measurement of food intake at 3 h post injection. Administration of anandamide induced significant hyperphagia. Pretreatment with the selective CB1 cannabinoid antagonist SR 141716 (30 μg 0.5 μl−1), 30 min prior to anandamide injection resulted in an attenuation of the anandamide‐induced hyperphagia (P<0.001). This study demonstrates that intrahypothalamic anandamide initiates appetite by stimulation of CB1 receptors, thus providing evidence on the involvement of hypothalamic endocannabinoids in appetite initiation.British Journal of Pharmacology (2001) 134, 1151–1154; doi:10.1038/sj.bjp.0704379
Prostacyclin receptor‐independent inhibition of phospholipase C activity by non‐prostanoid prostacyclin mimetics
Authors: Chow Kevin B S , Wong Yung H , Wise Helen 
Published: January 2005

Chinese hamster ovary (CHO) cells were transiently transfected with the mouse prostacyclin (mIP) receptor to examine IP agonist‐mediated stimulation of [3H]‐cyclic AMP and [3H]‐inositol phosphate production.
The prostacyclin analogues, cicaprost, iloprost, carbacyclin and prostaglandin E1, stimulated adenylyl cyclase activity with EC50 values of 5, 6, 25 and 95 nM, respectively. These IP agonists also stimulated the phospholipase C pathway with 10 – 40 fold lower potency than stimulation of adenylyl cyclase.
The non‐prostanoid prostacyclin mimetics, octimibate, BMY 42393 and BMY 45778, also stimulated adenylyl cyclase activity, with EC50 values of 219, 166 and 398 nM, respectively, but failed to stimulate [3H]‐inositol phosphate production.
Octimibate, BMY 42393 and BMY 45778 inhibited iloprost‐stimulated [3H]‐inositol phosphate production in a non‐competitive manner.
Activation of the endogenously‐expressed P2 purinergic receptor by ATP led to an increase in [3H]‐inositol phosphate production which was inhibited by the non‐prostanoid prostacyclin mimetics in non‐transfected CHO cells. Prostacyclin analogues and other prostanoid receptor ligands failed to inhibit ATP‐stimulated [3H]‐inositol phosphate production.
A comparison between the IP receptor‐specific non‐prostanoid ONO‐1310 and the structurally‐related EP3 receptor‐specific agonist ONO‐AP‐324, indicated that the inhibitory effect of non‐prostanoids was specific for those compounds known to activate IP receptors.
The non‐prostanoid prostacyclin mimetics also inhibited phospholipase C activity when stimulated by constitutively‐active mutant GαqRC, Gα14RC and Gα16QL transiently expressed in CHO cells. These drugs did not inhibit adenylyl cyclase activity when stimulated by the constitutively‐active mutant GαsQL.
These results suggest that non‐prostanoid prostacyclin mimetics can specifically inhibit [3H]‐inositol phosphate production by targeting Gq/11 and/or phospholipase C in CHO cells, and that this effect is independent of IP receptors.

British Journal of Pharmacology (2001) 134, 1375–1384; doi:10.1038/sj.bjp.0704388
Endothelin‐1 increases cholinergic nerve‐mediated contraction of human bronchi via tachykinin synthesis induction
Authors: D'Agostino Bruno , Advenier Charles , Falciani Maddalena , Gallelli Luca , Marrocco Giuseppina , Piegari Elena , Filippelli Amelia , Rossi Francesco 
Published: January 2005

In some asthmatics, muscarinic receptor antagonists are effective in limiting bronchoconstrictor response, suggesting an abnormal cholinergic drive in these subjects. There is a growing body of evidences indicating that cholinergic neurotransmission is also enhanced by endothelin‐1 (ET‐1) in rabbit bronchi, mouse trachea and in human isolated airway preparations.
We investigated the role of secondary mediators in ET‐1 induced potentiation of cholinergic nerve‐mediated contraction in human bronchi, in particular the possible role of neuropeptides in this phenomenon.
Bronchial tissues after endothelin treatment were exposed to a standard electrical field stimulation (EFS) (30% of EFS 30Hz)‐induced contraction. In addition, in some experiments, preparations were treated with a tachykinin NK2 receptor antagonist and subsequently exposed to the same protocol. HPLC and RIA were performed on organ bath fluid samples. Moreover, the human bronchi were used for the β‐PPT (preprotachykinin) mRNA extraction and semiquantitative reverse transcription polymerase chain reaction (RT – PCR), prior to and 30 – 40 min following ET‐1 challenge.
The selective tachykinin NK2 receptor antagonist, SR48968, was effective to reduce ET‐1 potentiation of EFS mediated contraction. HPLC or RIA showed significant increased quantities of NKA in organ bath effluents after EFS stimulation in bronchi pretreated with ET‐1. Finally, β‐PPT mRNA level after stimulation of bronchi with ET‐1 was increased about 2 fold respect to control untreated bronchi.
In conclusion, this study demonstrated that, at least in part, the ET‐1 potentiation of cholinergic nerve‐mediated contraction is mediated by tachykinin release, suggesting that in addition to nerves, several type of cells, such as airway smooth muscle cell, may participate to neuropeptide production.

British Journal of Pharmacology (2001) 134, 1447–1454; doi:10.1038/sj.bjp.0704395
Anti‐inflammatory effect of synthetic somatostatin analogues in the rat
Authors: Helyes Zsuzsanna , Pintér Erika , Németh József , Kéri György , Thán Márta , Oroszi Gábor , Horváth Anikó , Szolcsányi János 
Published: January 2005

Somatostatin (6.11 nmol kg−1 i.p.) inhibited neurogenic plasma extravasation evoked by 1% mustard oil and non‐neurogenic oedema induced by 5% dextran in the rat skin.
Cyclic synthetic octapeptide (TT‐248 and TT‐250) and heptapeptide (TT‐232) somatostatin analogues proved to be more effective in reducing neurogenic and non‐neurogenic inflammatory reactions but octreotide had no influence on either neurogenic or non‐neurogenic inflammation.
TT‐232 administered i.p. or i.v. (1.06 – 42.40 nmol kg−1) inhibited in a dose‐dependent manner the plasma extravasation evoked by mustard oil in the rat's paw. Neither diclofenac (15.78 – 315.60 μmol kg−1) nor the selective COX‐2 inhibitor meloxicam (2.95 – 569.38 μmol kg−1) attenuated the mustard oil‐induced neurogenic plasma extravasation.
TT‐232, diclofenac and meloxicam dose‐dependently diminished non‐neurogenic dextran‐oedema of the paw the ED35 values were 1.73 nmol kg−1 for TT‐232 and 34.37 μmol kg−1 for diclofenac.
TT‐232 inhibited in the dose range of 1.06 – 21.21 nmol kg−1 the bradykinin‐induced plasma extravasation in the skin of the chronically denervated paw.
Mustard oil‐induced cutaneous plasma extravasation was dose‐dependently diminished by s.c. TT‐232 1, 2, 4, 6 or 16 h after the treatment. TT‐232 (2×106, 2×212 and 2×530 nmol kg−1 per day s.c. for 18 days) caused dose‐dependent inhibition of chronic Freund adjuvant‐induced arthritis during the experimental period.
TT‐232 (200 and 500 nM) inhibited the release of SP, CGRP and somatostatin from the rat isolated trachea induced by electrical field stimulation (40 V, 0.1 ms, 10 Hz, 120 s) or by capsaicin (10−7 M), but did not influence the basal, non‐stimulated peptide release.
It is concluded that somatostatin analogues without endocrine functions as TT‐232 are promising compounds with a novel site of action for inhibition of non‐neurogenic and neurogenic inflammatory processes.

British Journal of Pharmacology (2001) 134, 1571–1579; doi:10.1038/sj.bjp.0704396