bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of pH on the inhibition of fatty acid amidohydrolase by ibuprofen
Authors: Holt Sandra , Nilsson Jonas , Omeir Romelda , Tiger Gunnar , Fowler Christopher J 
Published: January 2005

The pharmacological properties of fatty acid amidohydrolase (FAAH) at different assay pH values were investigated using [3H]‐anandamide ([3H]‐AEA) as substrate in rat brain homogenates and in COS‐7 cells transfected with wild type and mutant FAAH.
Rat brain hydrolysis of [3H]‐AEA showed pH dependency with an optimum around pH 8‐9. Between pH 6.3 and 8.2, the difference in activity was due to differences in the Vmax, rather than the KM values.
For inhibition of rat brain [3H]‐AEA metabolism by a series of known FAAH inhibitors, the potencies of the enantiomers of ibuprofen and phenylmethylsulphonyl fluoride (PMSF) were higher at pH 5.28 than at pH 8.37, whereas the reverse was true for oleyl trifluoromethylketone (OTMK) and arachidonoylserotonin. At both pH values, (−)ibuprofen was a mixed‐type inhibitor of FAAH. The Ki(slope) and Ki(intercept) values for (−)ibuprofen at pH 5.28 were 11 and 143 μM, respectively. At pH 8.37, the corresponding values were 185 and 3950 μM, respectively.
The pH dependency for the inhibition by OTMK and (−)ibuprofen was also seen in COS‐7 cells transiently transfected with either wild type, S152A or C249A FAAH. No differences in potencies between the wild type and mutant enzymes were seen.
It is concluded that the pharmacological properties of FAAH are highly pH‐dependent. The higher potency of ibuprofen at lower pH values raises the possibility that in certain types of inflamed tissue, the concentration of this compound following oral administration may be sufficient to inhibit FAAH.

British Journal of Pharmacology (2001) 133, 513–520; doi:10.1038/sj.bjp.0704113
Effects of YM471, a nonpeptide AVP V1A and V2 receptor antagonist, on human AVP receptor subtypes expressed in CHO cells and oxytocin receptors in human uterine smooth muscle cells
Authors: Tsukada Junko , Tahara Atsuo , Tomura Yuichi , Wada Koh‐ichi , Kusayama Toshiyuki , Ishii Noe , Yatsu Takeyuki , Uchida Wataru , Taniguchi Nobuaki , Tanaka Akihiro 
Published: January 2005

YM471, (Z)‐4′‐{4,4‐difluoro‐5‐[2‐(4‐dimethylaminopiperidino)‐2‐oxoethylidene]‐2,3,4,5‐tetrahydro‐1H‐1‐benzoazepine‐1‐carbonyl}‐2‐phenylbenzanilide monohydrochloride, is a newly synthesized potent vasopressin (AVP) receptor antagonist. Its effects on binding to and signal transduction by cloned human AVP receptors (V1A, V1B and V2) stably expressed in Chinese hamster ovary (CHO) cells, and oxytocin receptors in human uterine smooth muscle cells (USMC) were studied.
YM471 potently inhibited specific [3H]‐AVP binding to V1A and V2 receptors with Ki values of 0.62 nM and 1.19 nM, respectively. In contrast, YM471 exhibited much lower affinity for V1B and oxytocin receptors with Ki values of 16.4 μM and 31.6 nM, respectively.
In CHO cells expressing V1A receptors, YM471 potently inhibited AVP‐induced intracellular Ca2+ concentration ([Ca2+]i) increase, exhibiting an IC50 value of 0.56 nM. However, in human USMC expressing oxytocin receptors, YM471 exhibited much lower potency in inhibiting oxytocin‐induced [Ca2+]i increase (IC50=193 nM), and did not affect AVP‐induced [Ca2+]i increase in CHO cells expressing V1B receptors. Furthermore, in CHO cells expressing V2 receptors, YM471 potently inhibited the production of cyclic AMP stimulated by AVP with an IC50 value of 1.88 nM. In all assays, YM471 showed no agonistic activity.
These results demonstrate that YM471 is a potent, nonpeptide human V1A and V2 receptor antagonist which will be a valuable tool in defining the physiologic and pharmacologic actions of AVP.

British Journal of Pharmacology (2001) 133, 746–754; doi:10.1038/sj.bjp.0704117
Effects of GABAA receptor partial agonists in primary cultures of cerebellar granule neurons and cerebral cortical neurons reflect different receptor subunit compositions
Authors: Hansen Suzanne L , Ebert Bjarke , Fjalland Bjarne , Kristiansen Uffe 
Published: January 2005

Based on an unexpected high maximum response to piperidine‐4‐sulphonic acid (P4S) at human α1α6β2γ2 GABAA receptors expressed in Xenopus oocytes attempts to correlate this finding with the pharmacological profile of P4S and other GABAA receptor ligands in neuronal cultures from rat cerebellar granule cells and rat cerebral cortex were carried out.
GABA and isoguvacine acted as full and piperidine‐4‐sulphonic acid (P4S) as partial agonists, respectively, at α1β2γ2, α6β2γ2 and α1α6β2γ2 GABA receptors expressed in Xenopus oocytes with differences in potency.
Whole‐cell patch‐clamp recordings were used to investigate the pharmacological profile of the partial GABAA receptor agonists 4,5,6,7‐tetrahydroisoxazolo‐(5,4‐c)pyridin‐3‐ol (THIP), P4S, 5‐(4‐piperidyl)isoxazol‐3‐ol (4‐PIOL), and 3‐(4‐piperidyl)isoxazol‐5‐ol (iso‐4‐PIOL), and the competitive GABAA receptor antagonists Bicuculline Methbromide (BMB) and 2‐(3‐carboxypropyl)‐3‐amino‐6‐methoxyphenyl‐pyridazinium bromide (SR95531) on cerebral cortical and cerebellar granule neurons. In agreement with findings in oocytes, GABA, isoguvacine and P4S showed similar pharmacological profiles in cultured cortical and cerebellar neurones, which are known to express mainly α1, α2, α3, and α5 containing receptors and α1, α6 and α1α6 containing receptors, respectively.
4‐PIOL and iso‐4‐PIOL, which at GABAA receptors expressed in oocytes were weak antagonists, showed cell type dependent potency as inhibitors of GABA mediated responses. Thus, 4‐PIOL was slightly more potent at cortical neurones than at granule neurones and iso‐4‐PIOL was more potent in inhibiting isoguvacine‐evoked currents at cortical than at granule neurons. Furthermore the maximum response to 4‐PIOL corresponded to that of a partial agonist, whereas that of iso‐4‐PIOL gave a maximum response close to zero.
It is concluded that the pharmacological profile of partial agonists is highly dependent on the receptor composition, and that small structural changes of a ligand can alter the selectivity towards different subunit compositions. Moreover, this study shows that pharmacological actions determined in oocytes are generally in agreement with data obtained from cultured neurons.

British Journal of Pharmacology (2001) 133, 539–549; doi:10.1038/sj.bjp.0704121
Antioxidant activity of amiodarone on human lipoprotein oxidation
Authors: Lapenna Domenico , Ciofani Giuliano , Bruno Cristiana , Pierdomenico Sante D , Cuccurullo Franco 
Published: January 2005

Lipoprotein oxidation is crucial in atherogenic processes. Amiodarone is a lipophilic antiarrhythmic/antianginal drug which is able to influence the physicochemical status of biological lipid components. Since oxidation of lipids is affected by their physicochemical state and amiodarone binds to lipoproteins, we hypothesized that the drug may exert an antioxidant activity on human lipoprotein oxidation.
Dose‐dependent effects of therapeutically achievable amiodarone concentrations (1.5, 3, 5, 7 and 10 μM) were studied on copper‐catalysed oxidation of the non‐HDL fraction in vitro. Amiodarone inhibited oxidation as judged by generation of thiobarbituric acid reactive substances (TBARS), lipid hydroperoxides (LOOH) and fluorescent products of lipoperoxidation (FPL) as well as from the kinetics of conjugated diene formation. This antioxidant activity was significant at 1.5 μM with total inhibition at 10 μM and an IC50 of 4 μM. The primary in vivo metabolite of amiodarone, namely desethylamiodarone, also exhibited specific antioxidant properties although it was less effective than amiodarone with an IC50 of 7 μM.
In further in vivo experiments, susceptibility to copper‐mediated oxidation of the non‐HDL fraction was investigated before and 4 weeks after oral amiodarone administration to humans. Following treatment, significant inhibition of TBARS, LOOH and FPL generation was observed in comparison with baseline levels and a placebo‐treated control group, highlighting an effective antioxidant capacity of amiodarone in vivo.
Amiodarone did not change lipoprotein vitamin E and phospholipid content in vivo and did not show scavenging effects on oxidizing species involved in lipoprotein oxidation, such as peroxyl radicals, nor metal‐binding/inactivating properties, suggesting that physicochemical modifications of lipoprotein lipids induced by the lipophilic drug may be involved in its antioxidant activity.
In conclusion, amiodarone, and its primary metabolite desethylamiodarone, show previously unrecognized antioxidant activity on human lipoprotein oxidation. This effect is also evident in vivo and at therapeutically achievable drug concentrations. Thus, amiodarone may act as an antioxidant/antiatherosclerotic agent in humans, although this issue warrants further clinical study.

British Journal of Pharmacology (2001) 133, 739–745; doi:10.1038/sj.bjp.0704126
Relaxation to authentic nitric oxide and SIN‐1 in rat isolated mesenteric arteries: variable role for smooth muscle hyperpolarization
Authors: Plane Frances , Sampson Laura J , Smith Jennifer J , Garland Christopher J 
Published: January 2005

Authentic nitric oxide (NO; 0.1–10 μmoles) caused transient, dose‐dependent relaxation of phenylephrine‐induced tone without changing membrane potential in mesenteric arteries. Larger doses, above 10 μmoles, did not evoke more relaxation (maximal relaxation to 150 μmoles NO in denuded arteries, 69±7%, n=8) but stimulated muscle hyperpolarization (maximum 19±3 mV, n=5).
The soluble guanylyl cyclase inhibitor, 1H‐[1,2,4]oxadiazolo[4,3‐a]quinoxalin‐1‐one (ODQ; 10 μM), abolished relaxation to low doses of NO (n=4), but did not modify hyperpolarization with higher doses of NO (n=4). The potassium channel blocker charybdotoxin (ChTX; 50 nM) abolished hyperpolarization to high doses of NO and significantly reduced the maximal relaxation (to 43±6%, n=4; P<0.01). ODQ and ChTX together abolished tension and membrane potential change to all doses of NO (n=4).
All relaxations to 3‐morpholino‐sydnonimine (SIN‐1; 0.01–10 μM) were associated with hyperpolarization. When the endothelium was intact, ChTX inhibited hyperpolarization and relaxation to SIN‐1 (n=5), while iberiotoxin (IbTX; 50 nM) or 4‐aminopyridine (4‐AP; 500 μM) reduced relaxation by 40% and 20%, respectively and by 80% in combination (n=6 in each case).
In denuded arteries, relaxation to SIN‐1 was unaffected by either ChTX or ODQ alone, but abolished by the inhibitors together (n=6). Alone, 4‐AP did not alter relaxation, but in the presence of ODQ it reduced the maximal response by around 45% (n=6; P<0.01). 4‐AP, ODQ and IbTX together inhibited relaxation to SIN‐1 by 75% (n=6; P<0.01).
Therefore, cyclic guanosine 3′,5′‐monophosphate (cyclic GMP)‐independent smooth muscle hyperpolarization, possibly involving direct activation of calcium‐activated and voltage‐sensitive potassium channels, contributes to relaxation evoked by authentic NO and SIN‐1. However, the importance of each pathway depends on the source of NO and with SIN‐1 the relative contribution from each pathway is modified by the endothelium.

British Journal of Pharmacology (2001) 133, 665–672; doi:10.1038/sj.bjp.0704127
Nipecotic acid directly activates GABAA‐like ion channels
Authors: Barrett‐Jolley R 
Published: January 2005

The GABA‐related compound nipecotic acid is commonly used to inhibit GABA uptake. This report shows that nipecotic acid can also directly activate GABAA‐like chloride channels.
When applied to outside‐out patches of paraventricular neurones, nipecotic acid (1 mM) activated inward unitary currents (approximately 3 pA at a holding potential of −60 mV, ECl+44 mV).
The EC50 for ion channel activation was approximately 300 μM, 3 fold greater than that found for GABA itself in this preparation.
The nipecotic acid activated channels had similar conductance and kinetic properties to those of GABA activated channels in the same patches, reversed near ECl and were inhibited by bicuculline (3 μM).
This study indicates that for experiments in which relatively high concentrations of nipecotic acid are used, possible direct GABAA receptor agonist properties should be considered.

British Journal of Pharmacology (2001) 133, 673–678; doi:10.1038/sj.bjp.0704128
Functional characterization of α1‐adrenoceptor subtypes in human skeletal muscle resistance arteries
Authors: Jarajapu Yagna P R , Coats Paul , McGrath John C , Hillier Chris , MacDonald Allan 
Published: January 2005

α1‐adrenoceptor subtypes in human skeletal muscle resistance arteries were characterized using agonists noradrenaline (non‐selective) and A61603 (α1A‐selective), the antagonists prazosin (non‐selective), 5‐methyl‐urapidil (α1A‐selective) and BMY7378 (α1D‐selective) and the alkylating agent chloroethylclonidine (preferential for α1B).
Small arteries were obtained from the non‐ischaemic skeletal muscle of limbs amputated for critical limb ischaemia and isometric tension recorded using wire myography.
Prazosin antagonized responses to noradrenaline with a pA2 value of 9.18, consistent with the presence of α1‐adrenoceptors, although the Schild slope (1.32) was significantly different from unity.
5‐Methyl‐urapidil competitively antagonized responses to noradrenaline with a pKB value of 8.48 and a Schild slope of 0.99, consistent with the presence of α1A‐adrenoceptors. In the presence of 300 nM 5‐methyl‐urapidil, noradrenaline exhibited biphasic concentration response curves, indicating the presence of a minor population of a 5‐methyl‐urapidil‐resistant subtype.
Contractile responses to noradrenaline were not affected by 1 μM chloroethylclonidine suggesting the absence of α1B‐adrenoceptors. Maximum responses to noradrenaline and A61603 were reduced to a similar extent by 10 μM chloroethylclonidine, suggesting an effect of chloroethylclonidine at α1A‐adrenoceptors at the higher concentration.
BMY7378 (10 and 100 nM) had no effect on responses to noradrenaline. BMY7378 (1 μM) poorly shifted the potency of noradrenaline giving a pA2 of 6.52. These results rule out the presence of the α1D‐subtype.
These results show that contractile responses to noradrenaline in human skeletal muscle resistance arteries are predominantly mediated by the α1A‐adrenoceptor subtype with a minor population of an unknown α1‐adrenoceptor subtype.

British Journal of Pharmacology (2001) 133, 679–686; doi:10.1038/sj.bjp.0704130
SB‐272183, a selective 5‐HT1A, 5‐HT1B and 5‐HT1D receptor antagonist in native tissue
Authors: Watson J , Roberts C , Scott C , Kendall I , Collin L , Day N C , Harries M H , Soffin E , Davies C H , Randall A D , Heightman T , Gaster L , Wyman P , Parker C , Price G W , Middlemiss D N 
Published: January 2005

A novel compound, SB‐272183 (5‐Chloro‐2, 3‐dihydro‐6‐[4‐methylpiperazin‐1‐yl]‐1[4‐pyridin‐4‐yl]napth‐1‐ylaminocarbonyl]‐1H‐indole), has been shown to have high affinity for human 5‐HT1A, 5‐HT1B and 5‐HT1D receptors with pKi values of 8.0, 8.1 and 8.7 respectively and is at least 30 fold selective over a range of other receptors.
[35S]‐GTPγS binding studies showed that SB‐272183 acts as a partial agonist at human recombinant 5‐HT1A, 5‐HT1B and 5‐HT1D receptors with intrinsic activities of 0.4, 0.4 and 0.8 respectively, compared to 5‐HT. SB‐272183 inhibited 5‐HT‐induced stimulation of [35S]‐GTPγS binding at human 5‐HT1A and 5‐HT1B receptors to give pA2 values of 8.2 and 8.5 respectively. However, from [35S]‐GTPγS autoradiographic studies in rat and human dorsal raphe nucleus, SB‐272183 did not display intrinsic activity up to 10 μM but did block 5‐HT‐induced stimulation of [35S]‐GTPγS binding.
From electrophysiological studies in rat raphe slices in vitro, SB‐272183 did not effect cell firing rate up to 1 μM but was able to attenuate (+)8‐OH‐DPAT‐induced inhibition of cell firing to give an apparent pKb of 7.1.
SB‐272183 potentiated electrically‐stimulated [3H]‐5‐HT release from rat and guinea‐pig cortical slices at 100 and 1000 nM, similar to results previously obtained with the 5‐HT1B and 5‐HT1D receptor antagonist, GR127935.
Fast cyclic voltammetry studies in rat dorsal raphe nucleus showed that SB‐272183 could block sumatriptan‐induced inhibition of 5‐HT efflux, with an apparent pKb of 7.2, but did not effect basal efflux up to 1 μM.
These studies show that, in vitro, SB‐272183 acts as an antagonist at native tissue 5‐HT1A, 5‐HT1B and 5‐HT1D receptors.

British Journal of Pharmacology (2001) 133, 797–806; doi:10.1038/sj.bjp.0704133
Augmented acetylcholine‐induced translocation of RhoA in bronchial smooth muscle from antigen‐induced airway hyperresponsive rats
Authors: Chiba Yoshihiko , Sakai Hiroyasu , Misawa Miwa 
Published: January 2005

Acetylcholine (ACh)‐induced translocation of RhoA in bronchial smooth muscle of repeatedly antigen‐challenged rats that have a marked airway hyperresponsiveness (AHR) was examined.
ACh induced time‐ and concentration‐dependent translocation of RhoA to the plasma membrane, indicating an activation of RhoA in bronchial smooth muscle.
The level of ACh‐induced RhoA translocation was further increased markedly in the AHR group as compared to that in the control group.
It is suggested that the augmented activation of RhoA observed in the hyperresponsive bronchial smooth muscle might be responsible for the enhanced ACh‐induced Ca2+ sensitization of bronchial smooth muscle contraction associated with AHR.

British Journal of Pharmacology (2001) 133, 886–890; doi:10.1038/sj.bjp.0704137
Endogenous sulphur‐containing amino acids: potent agonists at presynaptic metabotropic glutamate autoreceptors in the rat central nervous system
Authors: Croucher Martin J , Thomas Lisa S , Ahmadi Hootan , Lawrence Victoria , Harris John R 
Published: January 2005

We have recently demonstrated that presynaptically located metabotropic glutamate (mGlu) autoreceptors regulate synaptic glutamate release both in vitro and in vivo. We now report a positive modulatory action of the sulphur‐containing amino acids (SCAAs), L‐cysteic acid (CA) and L‐cysteine sulphinic acid (CSA), at presynaptic group I mGlu receptors, specifically of the mGlu5 subtype, acting to enhance synaptic glutamate release from the rat forebrain in vitro.
Neuronal glutamate release was monitored using electrically‐evoked efflux of preloaded [3H]‐D‐aspartate from rat forebrain hemisections.
Both CA (3 – 100 μM) and CSA (1 – 100 μM), in addition to the selective group I mGlu receptor agonist, (S)‐3,5‐dihydroxyphenylglycine ((S)‐DHPG), concentration‐dependently enhanced electrically‐stimulated efflux of [3H]‐D‐aspartate from the rat forebrain slices. Basal efflux of label remained unchanged.
The inhibitory activity of the broad spectrum mGlu receptor antagonist, (±)‐α‐methyl‐4‐carboxyphenylglycine ((±)‐MCPG; 200 μM), coupled with the inactivity of the selective mGlu1 receptor antagonists, (R,S)‐1‐aminoindan‐1,5‐dicarboxylic acid ((R,S)‐AIDA; 100 – 500 μM) and the more potent (+)‐2‐methyl‐4‐carboxyphenylglycine (LY367385; 10 μM) against these responses, indicates an action of the SCAAs at the mGlu5 receptor subtype. This proposal is supported by the potent inhibition of these responses by the selective, non‐competitive mGlu5 receptor antagonist, 2‐methyl‐6‐(phenylethynyl)pyridine (MPEP; 10 μM). The observed enhancement of the responses to high concentrations of CA by the selective mGlu5 receptor desensitization inhibitor, cyclothiazide (CYZ; 10 μM), is also consistent with this concept.
Administration of the agonists in the presence of bovine serum albumin (BSA; 5 – 15 mg ml−1) markedly attenuated the positive modulatory responses observed, strongly supporting a role for arachidonic acid in the expression of these mGlu5 receptor‐mediated responses.
The regulatory actions of SCAAs on synaptic glutamate release demonstrated in the present study may provide a physiological function for these putative neurotransmitter amino acids in the mammalian brain. These central actions of the SCAAs may have wide‐ranging implications for a range of neurological and neuropsychiatric disease states and their treatment.

British Journal of Pharmacology (2001) 133, 815–824; doi:10.1038/sj.bjp.0704138
Identification of two distinct vasodilator pathways activated by ATP in the mesenteric bed of the rat
Authors: Stanford Salome J , Gitlin Jonathan M , Mitchell Jane A 
Published: January 2005

Adenosine 5′‐triphosphate (ATP) has important roles in the cardiovascular system, modulating vascular tone by acting as both a vasoconstrictor and a vasodilator.
The dilator function of ATP is traditionally thought to be monophasic and mediated primarily by nitric oxide (NO).
Here we have identified the endothelium‐dependent biphasic nature of ATP‐induced vasodilatation of the rat isolated mesenteric bed and investigated the two distinct pathways involved.
ATP, at doses of 1×10−11 to 1×10−8 moles, induced transient relaxations that were inhibited by the NO synthase (NOS) inhibitor, NG‐nitro‐L‐arginine methyl ester (L‐NAME: 1×10−4 M), the soluble guanylyl cyclase inhibitor, 1H‐[1,2,4]Oxadiazolo[4,3‐a]quinoxalin‐1‐one (ODQ: 3×10−6 M) and KCl (6×10−2 – 1.2×10−1 M).
At doses upwards of 1×10−8 moles (1×10−8 – 3×10−7 moles), ATP also induced prolonged vasodilatations which were unaltered by L‐NAME, L‐NAME (1×10−3 M) and indomethacin (1×10−5 M), or by ODQ, but were abolished in the presence of KCl.
In addition, the cannabinoid CB1 receptor antagonist SR141716A (1×10−5 M) was found to inhibit the second prolonged phase of vasodilatation. However, at the concentration used SR141716A is reported to be non‐selective. A second CB1 receptor antagonist, AM251 (1×10−6 M), had a small but significant inhibitory effect on the second phase of ATP‐induced vasodilatation. SR141716A, AM251 and KCl (6×10−2 – 1.2×10−1 M) all inhibited anandamide‐induced relaxation of the isolated mesenteric bed.
These observations demonstrate that ATP stimulates vasodilatation of the mesenteric bed by two distinct mechanisms involving the release of NO and an EDHF. In the absence of better pharmacological tools we can only speculate as to the involvement of an endogenous CB1 receptor ligand in these responses.

British Journal of Pharmacology (2001) 133, 825–832; doi:10.1038/sj.bjp.0704139