bluuebunny/crossref_metadata_2025_split huggingface dataset:
Blockade of N‐type Ca2+ current by cilnidipine (FRC‐8653) in acutely dissociated rat sympathetic neurones
Authors: Uneyama Hisayuki , Takahara Akira , Dohmoto Hideki , Yoshimoto Ryota , Inoue Kazuhide , Akaike Norio 
Published: January 2005

The inhibitory effects of cilnidipine (FRC‐8653) and various organic Ca2+ channel blockers on high voltage‐activated Ba2+ currents (HVA IBa) in rat sympathetic neurones were examined by means of the conventional whole‐cell patch‐clamp recording mode under voltage‐clamped conditions.
HVA IBa was classified into three different current components with subtype selective peptide Ca2+ channel blockers. No ω‐Agatoxin IVA‐sensitive (P‐type) or ω‐conotoxin MVIIC‐sensitive (Q‐type) current components were observed. Most (>85%) IBa was found to consist of ω‐conotoxin GVIA‐sensitive N‐type components.
The application of cilnidipine inhibited HVA IBa in a concentration‐dependent manner. The Kd value for cilnidipine was 0.8 μM. Cilnidipine did not shift the current‐voltage (I‐V) relationship for HVA IBa, as regards the threshold potential and peak potential where the amplitude reached a maximum.
High concentrations of three hypotensive Ca2+ channel blockers, nifedipine, diltiazem and verapamil, all inhibited HVA IBa in a concentration‐dependent manner. The Kd values for nifedipine, diltiazem and verapamil were 131, 151 and 47 μM, respectively. A piperazine‐type Ca2+ channel blocker, flunarizine, showed a relatively potent blocking action on IBa. The Kd value was about 3 μM.
These results thus show that cilnidipine potently inhibits the sympathetic Ca2+ channels which predominantly consist of an ω‐Cg‐GVIA‐sensitive component. This blockade of the N‐type Ca2+ channel, as well as the L‐type Ca2+ channel by cilnidipine suggests that it could be used therapeutically for treatment of hypersensitive sympathetic disorders associated with hypertension.

British Journal of Pharmacology (1997) 122, 37–42; doi:10.1038/sj.bjp.0701342
Effect of adenosine and some of its structural analogues on the conductance of NMDA receptor channels in a subset of rat neostriatal neurones
Authors: Nörenberg W. , Wirkner K. , Illes P. 
Published: January 2005

In order to investigate the modulatory effects of adenosine on excitatory amino acid projections onto striatal medium spiny neurones, whole‐cell patch clamp experiments were carried out in rat brain slices. The effects of various agonists for P1 (adenosine) and P2 (ATP) purinoceptors and their antagonists were investigated. The A2A receptor agonist 2‐p‐(2‐carboxyethyl)phenethylamino‐5′‐N‐ethylcarboxamidoadenosine (CGS 21680; 0.1 μM), the A1 receptor agonist 2‐chloro‐N6‐cyclopentyladenosine (CCPA; 10 μM) and the non‐selective P1 purinoceptor antagonist 8‐(p‐sulphophenyl)‐theophylline (8‐SPT; 100 μM) did not alter the resting membrane potential, the threshold current necessary to elicit an action potential, the amplitude of spikes, their rise time, the amplitude of the afterhyperpolarization (AHP) and the time to peak of the AHP.
N‐methyl‐D‐aspartate (NMDA; 1–1000 μM) caused a concentration‐dependent inward current which was larger in the absence than in the presence of Mg2+ (1.3 mM). In a subset of striatal neurones, the current response to NMDA (10 μM) and the accompanying increase in conductance were both inhibited by CGS 21680 (0.01–1 μM). The effect of CGS 21680 (0.1 μM) persisted in the presence of tetrodotoxin (0.5 μM) or in a Ca2+‐free medium, under conditions when synaptically mediated influences may be negligible.
The A3 receptor agonist N6‐2‐(4‐aminophenyl)ethyladenosine (APNEA; 0.1–10 μM) also diminished the effect of NMDA (10 μM), while the A1 receptor agonists CCPA (0.01–10 μM) and (2S)‐N6‐[2‐endo‐norbornyl]adenosine [S(−)‐ENBA; 10 μM] as well as the endogenous, non‐selective P1 purinoceptor agonist adenosine (100 μM) were inactive. The endogenous non‐selective P2 purinoceptor agonist ATP (1000 μM) also failed to alter the current response to NMDA (10 μM). Adenosine (100 μM), but not ATP (1000 μM) became inhibitory after blockade of nucleoside uptake by S(4‐nitrobenzyl)‐6‐thioguanosine (NBTG; 30 μM).
8‐(p‐Sulphophenyl)‐theophylline (8‐SPT; 100 μM), as well as the A2A receptor antagonist 8‐(3‐chlorostyryl)caffeine (CSC; 1 μM) and the A1 receptor antagonist 8‐cyclopentyl‐1,3‐dipropylxanthine (DPCPX) at 0.03, but not 0.003 μM abolished the inhibitory action of CGS 21680 (0.1 μM). None of these compounds altered the effect of NMDA (10 μM) by itself. DPCPX (0.03 μM) prevented the inhibition by APNEA (10 μM).
There was no effect of CGS 21680 (0.1 μM), when guanosine 5′‐O‐(3‐thiodiphosphate (GDP‐β‐S; 300 μM) was included in the pipette solution in order to block G protein‐mediated reactions.
In conclusion, adenosine receptors, probably of the A2A‐subtype, inhibit the conductance of NMDA receptor channels in a subset of medium spiny neurones of the rat striatum by a transduction mechanism which involves a G protein.

British Journal of Pharmacology (1997) 122, 71–80; doi:10.1038/sj.bjp.0701347
Development of basal and induced testosterone hydroxylase activity in the chicken embryo in ovo
Authors: Paolini Moreno , Pozzetti Laura , Sapone Andrea , Luigi Biagi Gian , Cantelli‐Forti Giorgio 
Published: January 2005

The sensitivity of the developing embryo to xenobiotics is highly dependent on the expression of metabolizing enzymes including cytochromes P450 (CYP). In the present study, therefore, the ontogeny of the CYP‐dependent system in the chick was investigated with testosterone hydroxylase activity as a marker of CYP expression.
Chicken embryo livers were assayed for basal and phenobarbitone (PB)‐induced regio‐ and stereo‐selective testosterone hydroxylase activity, from the first appearance of the liver as a discrete organ at 5 days of incubation through day 10 posthatching. In addition, whole embryo preparations were assayed at 3 and 4 days of incubation.
Whereas testosterone 16β‐hydroxylase and androst‐4‐ene‐3,17‐dione‐linked activities were expressed during all stages of embryonic development, testosterone 6α‐, 6β‐, 7α‐ and 16α‐hydroxylase activities were observed only in basal embryos from 8 days of incubation. Furthermore, testosterone 2α‐ and 2β‐ hydroxylase activities were detected exclusively from 10 days of incubation onward. All activities increased steadily throughout development as did the responsiveness of the embryonic liver to PB induction.
A typical pattern of development with a higher activity from 10 to 14 days of incubation (testosterone 16α‐, 7α‐, 6α‐ and 2β‐hydroxylase activities; up to 4.1±0.3 pmol mg−1 protein min−1 at 13 days of incubation for testosterone 7α‐hydroxylase) or shifted to 14 to 18 days of incubation (testosterone 6β‐, 2α‐ and 16β‐hydroxylase activities: up to 56.6±1.4 pmol mg−1 protein min−1 at 16 days of incubation for testosterone 6β‐hydroxylase) was observed. There was a tendency towards an increased activity for all activities around hatching, specifically from 19 days of incubation to 4 days posthatching (up to 1,759.3±179.4 pmol mg−1 protein min−1 at 1 day posthatching for androst‐4‐ene‐3,17‐dione‐linked activity).
The highest level of PB‐induced enzyme activity was observed for testosterone 2α‐hydroxylase activity (95.14±7.35 and 660.19±45.27 pmol mg−1 protein min−1) at 12 days of incubation and day 3 posthatching, respectively. Except for testosterone 2α‐ and 2β‐hydroxylase activities at 3 to 4 days of incubation, all metabolites were detectable during the first period of organogenesis in the presence of PB.
The use of highly specific substrates, studies on the immunoinhibition of metabolism by polyclonal antibodies raised against highly purified rat CYPs, and the use of selective inhibitors seemed to reveal a wide pleiotropic response with the posssible presence in liver of PB‐treated chickens of CYP1A together with CYP2H1/H2, CYP2E and CYP3A.

British Journal of Pharmacology (1997) 122, 344–350; doi:10.1038/sj.bjp.0701352
The interaction between methylene blue and the cholinergic system
Authors: Pfaffendorf M. , Bruning T. A. , Batink H. D. , Van Zwieten P. A. 
Published: January 2005

The inhibitory effects of methylene blue (MB) on different types of cholinesterases and [3H]‐N‐methylscopolamine ([3H]‐NMS) binding to muscarinic receptors were studied.
Human plasma from young healthy male volunteers, purified human pseudocholinesterase and purified bovine true acetylcholinesterase were incubated with acetylcholine and increasing concentrations of MB (0.1–100 μmol l−1) in the presence of the pH‐indicator m‐nitrophenol for 30 min at 25°C. The amount of acetic acid produced by the enzymatic hydrolysis of acetylcholine was determined photometrically.
Rat cardiac left ventricle homogenate was incubated with [3H]‐NMS and with increasing concentrations of MB (0.1 nmol l−1–100 μmol l−1) at 37°C for 20 min. The binding of [3H]‐NMS to the homogenate was quantified by a standard liquid scintillation technique.
MB inhibited the esterase activity of human plasma, human pseudocholinesterase and bovine acetylcholinesterase concentration‐dependently with IC50 values of 1.05±0.05 μmol l−1, 5.32±0.36 μmol l−1 and 0.42±0.09 μmol l−1, respectively. MB induced complete inhibition of the esterase activity of human plasma and human pseudocholinesterase, whereas bovine acetylcholinesterase was maximally inhibited by 73±3.3%.
MB was able to inhibit specific [3H]‐NMS binding to rat cardiac left ventricle homogenate completely with an IC50 value of 0.77±0.03 μmol l−1, which resulted in a Ki value for MB of 0.58±0.02 μmol l−1.
In conclusion, MB may be considered as a cholinesterase inhibitor with additional, relevant affinity for muscarinic binding sites at concentrations at which MB is used for investigations into the endothelial system. In our opinion these interactions between MB and the cholinergic system invalidate the use of MB as a tool for the investigation of the L‐arginine‐NO‐pathway, in particular when muscarinic receptor stimulation is involved.

British Journal of Pharmacology (1997) 122, 95–98; doi:10.1038/sj.bjp.0701355
Acute nociception mediated by hindpaw P2X receptor activation in the rat
Authors: Bland‐Ward P. A. , Humphrey P. P. A. 
Published: January 2005

The functional consequences of P2X receptor activation on peripheral sensory neurones have been investigated in vivo. Behavioural indices of acute nociception were monitored in the conscious rat following subplantar injection of adenosine 5′‐triphosphate (ATP), α,β‐methylene ATP, adenosine 5′‐diphosphate (ADP) and adenosine.
Signs of overt nociception, i.e. hindpaw lifting and licking, were apparent in animals injected subplantar with the P2X receptor agonist, α,β‐methylene ATP. Nociceptive behaviours continued for 15 min following administration of α,β‐methylene ATP (200 nmol) and were dose‐related (0–5 min hindpaw lifting times after injection of α,β‐methylene ATP 100 nmol and 1000 nmol were 89±26 s and 232±11 s, respectively). Subplantar ATP evoked a modest response only at the highest dose tested (1000 nmol; 0–5 min hindpaw lifting time 66±19 s) whilst ADP or adenosine (both 600 nmol) elicited negligible spontaneous nociceptive activity.
Morphine (3 mg kg−1, i.v.) abolished hindpaw licking behaviour induced by subplantar injection of either α,β‐methylene ATP (600 nmol) or bradykinin (1 nmol) and substantially reduced (88±5%) paw licking in formalin (0.5%, 0.1 ml) injected animals. In contrast, hindpaw lifting was only modestly inhibited (34±11%) in morphine‐pretreated animals that had received subplantar bradykinin and was unaffected in rats in which the noxious stimulus was either subplantar α,β‐methylene ATP or formalin. Pretreatment of hindpaws with subplantar bupivacaine (1% w/v, 0.1 ml) abolished α,β‐methylene ATP‐evoked nociceptive behaviours.
Hindpaw lifting and licking mediated by α,β‐methylene ATP (600 nmol, subplantar) were inhibited (72±15% and 95±5%, respectively) by 30 min local pretreatment with 600 nmol α,β‐methylene ATP. Subplantar α,β‐methylene ATP pretreatment did not inhibit behaviour stimulated by subsequent bradykinin (1 nmol) or formalin (0.5%, 0.1 ml) injection into the hindpaw.
Desensitization of small diameter sensory neurones with a single subplantar injection of capsaicin (100 μg) abolished all behaviours indicative of spontaneous nociceptive sensation in animals subsequently injected with α,β‐methylene ATP (600 nmol), bradykinin (1 nmol) or formalin (0.5%, 0.1 ml).
We conclude that activation of P2X receptors present on small diameter (capsaicin‐sensitive) primary afferent neurones in the rat hindpaw mediates behaviour indicative of acute nociception.

British Journal of Pharmacology (1997) 122, 365–371; doi:10.1038/sj.bjp.0701371
Stable expression of human kinin B1 receptor in 293 cells: pharmacological and functional characterization
Authors: Bastian S. , Loillier B. , Paquet J. L. , Pruneau D. 
Published: January 2005

We compared the binding properties of [3H]‐desArg10‐[Leu9]‐kallidin, a radiolabelled kinin B1 receptor antagonist, to membranes from IMR‐90 human embryonic fibroblasts and from 293 cells transiently or stably transfected with the human B1 receptor.
The dissociation constant (KD) of [3H]‐desArg10‐[Leu9]‐kallidin and the affinity of several kinin receptor agonists and antagonists were similar between the native and cloned receptor, either transiently or stably expressed in 293 cells. In IMR‐90 cells, the rank order of potency was that expected for a kinin B1 receptor.
The receptors transiently or stably expressed in 293 cells were fully functional with respect to their signalling properties. Phosphoinositide hydrolysis was increased in a concentration‐dependent manner by the B1 receptor agonist, desArg10‐kallidin. Functional coupling to the calcium pathway was also demonstrated for the native and stably expressed human B1 receptor.
In conclusion, the established stable and functional 293 cell clone may provide an important tool for further analysis of the molecular mechanisms involved in binding, activation, and coupling of the kinin B1 receptor.

British Journal of Pharmacology (1997) 122, 393–399; doi:10.1038/sj.bjp.0701380
The contrasting effects of dendrotoxins and other potassium channel blockers in the CA1 and dentate gyrus regions of rat hippocampal slices
Authors: Southan A. P. , Owen D. G. 
Published: January 2005

The effects of potassium channel blocking compounds on synaptic transmission in the CA1 and dentate gyrus regions of the rat hippocampus were examined by means of simultaneous field potential recording techniques in brain slices.
4‐Aminopyridine (4‐AP) enhanced the excitatory postsynaptic potential (e.p.s.p.) and induced multiple population spike responses in both regions. EC50 values were 6.7 μM in the CA1 (n=5) and 161.7 μM (n=5) in the dentate gyrus.
Tetraethylammonium (TEA) increased the amplitude and induced broadening of the population spike in both regions. In the dentate gyrus (n=5) a single slow spike response was introduced (EC50 12.8 mM) and in the CA1 region (n=5) the response was transformed into two wide spikes (EC50 2.6 mM).
In the CA1 region all of the dendrotoxins (toxin I, toxin K, α‐Dtx and δ‐Dtx) induced multiple population spikes and enlarged e.p.s.p. responses. Potentials recorded simultaneously in the dentate gyrus exhibited comparatively minor enhancements. The EC50 value for toxin I in the CA1 was calculated to be 237 nM (n=4). Estimated EC50 values were obtained for α‐Dtx (1.1 μM, n=3), toxin K (411 nM, n=4) and δ‐Dtx (176 nM, n=3).
In the presence of toxin I, DL‐2‐amino‐5‐phosphonovaleric acid (APV) induced slight reduction of the late e.p.s.p. phase (n=3). 6‐Cyano‐7‐nitroquinoxaline‐2,3‐dione (CNQX) abolished all population spikes leaving a late slow positive waveform (n=3). Co‐application of APV and CNQX abolished all postsynaptic responses.
Charybdotoxin (CbTx) was significantly less potent than the dendrotoxins and had mixed actions in the CA1 region (n=3). Again the dentate gyrus exhibited reduced sensitivity (n=3).
In the presence of mast cell degranulating peptide (MCDP), enhancement of the CA1 field potential response (n=5) was greater than that observed in the dentate gyrus (n=5).
The results show that some potassium channel modulators can profoundly enhance CA1 region synaptic responses in the absence of notable changes in dentate gyrus excitability. Selective enhancement of defined synaptic pathways by potassium channel modulators may prove to have considerable therapeutic potential.

British Journal of Pharmacology (1997) 122, 335–343; doi:10.1038/sj.bjp.0701392
Effects of cannabinoid receptor ligands on electrophysiological properties of myenteric neurones of the guinea‐pig ileum
Authors: López‐Redondo F. , Lees G. M. , Pertwee R. G. 
Published: January 2005

The effect of cannabinoid receptor agonists was studied in guinea‐pig myenteric neurones in vitro by use of conventional intracellular recording techniques.
Exposure of myenteric neurones of the S‐cell type to the cannabinoid receptor agonists WIN 55,212‐2 (100 nM) and CP 55,940 (100 nM) reversibly and significantly depressed the amplitude of fast excitatory synaptic potentials (fast e.p.s.ps) by 46% and 37%, respectively.
The depressant effect of WIN 55,212‐2 and CP 55,940 on fast e.p.s.p. amplitude (expressed as the area above the amplitude‐time curve (mVs)) was significantly greater than that of the vehicle, Tween 80, which had no detectable effect.
The inhibitory effect of WIN 55,212‐2 appeared to be concentration‐dependent over the range 1–100 nM. WIN 55,212‐3, its (−)‐enantiomer (100 nM), was inactive.
The cannabinoid CB1 receptor antagonist, SR141716A (1 μM), reversed the inhibitory effects of WIN 55,212‐2 on fast e.p.s.ps in 38% of neurones tested (3/8) and acetylcholine (ACh)‐induced depolarizations in 42% of neurones tested (5/12).
When tested on its own, SR141716A (1 μM) caused a 40–50% reduction in the amplitude of fast e.p.s.ps (n=9).
WIN 55,212‐2 reversibly depressed the amplitude of the slow e.p.s.p. and, in 2 out of 7 neurones, this effect was reversed by SR141716A (1 μM).
It is concluded that cannabinoid‐induced inhibition of fast cholinergic synaptic transmission occurred by reversible activation of both presynaptic and postsynaptic CB1 receptors and that slow excitatory synaptic transmission can also be reversibly depressed by cannabinoids. Furthermore, it would seem that subpopulations of myenteric S‐neurones and their synapsing cholinergic and non‐cholinergic, non‐adrenergic terminals are not endowed with cannabinoid receptors.

British Journal of Pharmacology (1997) 122, 330–334; doi:10.1038/sj.bjp.0701393
κ1‐ and κ2‐opioid receptors mediating presynaptic inhibition of dopamine and acetylcholine release in rat neostriatum
Authors: Schoffelmeer Anton N. M. , Hogenboom Francois , Mulder Arie H. 
Published: January 2005

The effects of selective opioid receptor agonists and antagonists on N‐methyl‐D‐aspartate (NMDA, 10 μM)‐induced release of [3H]‐dopamine and [14C]‐acetylcholine (ACh) from superfused neostriatal slices were studied to investigate the possible occurrence of functional κ‐opioid receptor subtypes in rat brain.
The κ receptor agonists (−)‐ethylketocyclazocine ((−)‐EKC), U69593 and the endogenous opioid peptide dynorphin A1–13 caused a naloxone‐reversible inhibition of NMDA‐induced [3H]‐dopamine release, with pD2 values of about 9, 8.5 and 8.2, respectively, whereas both the μ agonist Tyr‐D‐Ala‐Gly‐(NMe)Phe‐Gly‐ol (DAMGO) and theδ agonist D‐Pen2‐D‐Pen5‐enkephalin (DPDPE) were ineffective in this respect. The inhibitory effect of submaximally effective concentrations of dynorphin A1–13, U69593 and (−)‐EKC on NMDA‐induced [3H]‐dopamine release were not changed by the δ1/δ2‐opioid receptor antagonist naltrindole (up to a concentration of 1 μM), but reversed by the κ receptor antagonist nor‐binaltorphimine (nor‐BNI), with an IC50 as low as 0.02 nM, indicating the involvement of U69593‐sensitive κ1‐opioid receptors.
NMDA‐induced [14C]‐ACh release was reduced in a naloxone‐reversible manner by DPDPE (pD2 about 7.2), dynorphin A1–13 (pD2 6.7) and EKC (pD2 6.2), but not by U69593 and DAMGO. The inhibitory effect of a submaximally effective concentration of DPDPE, unlike those of dynorphin A1–13 and (−)‐EKC, on NMDA‐induced [14C]‐ACh release was antagonized by naltrindole with an IC50 of 1 nM, indicating the involvement of δ‐opioid receptors in the inhibitory effect of DPDPE. On the other hand, the inhibitory effects of dynorphin A1–13 and (−)‐EKC on [14C]‐ACh release were readily antagonized by nor‐BNI with an IC50 of about 3 nM. A 100 fold higher concentration of nor‐BNI also antagonized the inhibitory effect of DPDPE, indicating the involvement of U69593‐insensitive κ2‐opioid receptors in the inhibitory effects of dynorphin A1–13 and (−)‐EKC.
Although naloxone benzoylhydrazone (NalBzoH), displaying high affinity towards the putative κ3‐opioid receptor, antagonized the inhibitory effects of dynorphin A1–13 and (−)‐EKC on [3H]‐dopamine and [14C]‐ACh release as well as that of U69593 on [3H]‐dopamine release, it displayed a low apparent affinity (IC50 about 100 nM) in each case.
In conclusion, whereas activation of κ1‐opioid receptors causes presynaptic inhibition of NMDA‐induced dopamine release, κ2 receptor activation results in inhibition of ACh release in rat neostriatum. As such, this study is the first to provide unequivocal in vitro evidence for the existence of functionally distinct κ‐opioid receptor subtypes in the brain.

British Journal of Pharmacology (1997) 122, 520–524; doi:10.1038/sj.bjp.0701394
RPR 106541, a novel, airways‐selective glucocorticoid: effects against antigen‐induced CD4+T lymphocyte accumulation and cytokine gene expression in the Brown Norway rat lung
Authors: Underwood S. L. , Raeburn D. , Lawrence C. , Foster M. , Webber S. , Karlsson J. A. 
Published: January 2005

The effects of a novel 17‐thiosteroid, RPR 106541, were investigated in a rat model of allergic airway inflammation.
In sensitized Brown Norway rats, challenge with inhaled antigen (ovalbumin) caused an influx of eosinophils and neutrophils into the lung tissue and airway lumen. In the lung tissue there was also an accumulation of CD4+ T lymphocytes and increased expression of mRNA for interleukin‐4 (IL‐4) and IL‐5, but not interferon‐γ (IFN‐γ). These findings are consistent with an eosinophilia orchestrated by activated Th2‐type cells.
RPR 106541 (10–300 μg kg−1), administered by intratracheal instillation into the airways 24 h and 1 h before antigen challenge, dose‐dependently inhibited cell influx into the airway lumen. RPR 106541 (100 μg kg−1) caused a significant (P<0.01) (98%) inhibition of eosinophil influx and a significant (P<0.01) (100%) inhibition of neutrophil influx. RPR 106541 was approximately 7 times and 4 times more potent than budesonide and fluticasone propionate, respectively.
When tested at a single dose (300 μg kg−1), RPR 106541 and fluticasone each caused a significant (P<0.01) (100%) inhibition of CD4+ T cell accumulation in lung tissue. Budesonide (300 μg kg−1) had no significant effect. RPR 106541 and fluticasone (300 μg kg−1), but not budesonide (300 μg kg−1), significantly (P<0.05) inhibited the expression within lung tissue of mRNA for IL‐4. RPR 106541 (300 μg kg−1) also significantly (P<0.05) inhibited expression of mRNA for IL‐5.
The high topical potency of RPR 106541 in this model, which mimics important aspects of airway inflammation in human allergic asthmatics, suggests that this glucocorticoid may be useful in the treatment of bronchial asthma.

British Journal of Pharmacology (1997) 122, 439–446; doi:10.1038/sj.bjp.0701398