bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modulation of the gating of ClC‐1 by S‐(–) 2‐(4‐chlorophenoxy) propionic acid
Authors: Aromataris E C , Astill D St J , Rychkov G Y , Bryant S H , Bretag A H , Roberts M L 
Published: January 2005

Using whole‐cell patch‐clamping and Sf‐9 cells expressing the rat skeletal muscle chloride channel, rClC‐1, the cellular mechanism responsible for the myotonic side effects of clofibrate derivatives was examined.
RS‐(±) 2‐(4‐chlorophenoxy)propionic acid (RS‐(±) CPP) and its S‐(−) enantiomer produced pronounced effects on ClC‐1 gating. Both compounds caused the channels to deactivate more rapidly at hyperpolarizing potentials, which showed as a decrease in the time constants of both the fast and slow deactivating components of the whole cell currents. Both compounds also produced a concentration‐dependent shift in the voltage dependence of channel apparent open probability to more depolarizing potentials, with an EC50 of 0.79 and 0.21 mM for the racemate and S‐(−) enantiomer respectively. R‐(+) CPP at similar concentrations had no effect on gating. RS‐(±) CPP did not block the passage of Cl− through the pore of rClC‐1.
ClC‐1 is gated by Cl− binding to a site within an access channel and S‐(−) CPP alters gating of the channel by decreasing the affinity of this binding site for Cl−. Comparison of the EC50 for RS‐(±) CPP and S‐(−) CPP indicates that R‐(+) CPP can compete with the S‐(−) enantiomer for the site but that it is without biological activity.
RS‐(±) CPP produced the same effect on rClC‐1 gating when added to the interior of the cell and in the extracellular solution.
S‐(−) CPP modulates the gating of ClC‐1 to decrease the membrane Cl− conductance (GCl), which would account for the myotonic side effects of clofibrate and its derivatives.

British Journal of Pharmacology (1999) 126, 1375–1382; doi:10.1038/sj.bjp.0702459
Functional evidence of α1D‐adrenoceptors in the vasculature of young and adult spontaneously hypertensive rats
Authors: Villalobos‐Molina Rafael , López‐Guerrero J Javier , Ibarra Maximiliano 
Published: January 2005

The role of α1D‐adrenoceptors in the vasculature of spontaneously hypertensive (SHR) and normotensive Wistar Kyoto rats (WKY), of different ages was assessed in pithed rats by the use of the selective α1D‐adrenoceptor antagonist BMY 7378 (8‐[2‐[4‐(2‐methoxyphenyl)‐1‐piperazinyl]‐ethyl]‐8‐azaspiro [4.5]decane‐7,9‐dione dihydrochloride). BMY 7378 displaced the pressor effect of phenylephrine in young pre‐hypertensive pithed SHR rats, but produced no effect in young WKY rats (dose ratio of 3.4 and 1.6, respectively), while in adult rats BMY 7378 produced a greater shift in the phenylephrine response curve than in younger animals (dose ratio of 3.2 and 6.2 in WKY and SHR, respectively). The presence of α1D‐adrenoceptors in the vasculature of pre‐hypertensive rats, suggests its role in the pathogenesis/maintenance of increased blood pressure.British Journal of Pharmacology (1999) 126, 1534–1536; doi:10.1038/sj.bjp.0702468
P2Y receptor‐mediated Ca2+signalling in cultured rat aortic smooth muscle cells
Authors: Pediani J D , McGrath J C , Wilson S M 
Published: January 2005

ATP, UTP, ADP and ADP‐β‐S elicited Ca2+‐signals in cultured aortic smooth muscle cells although ADP, UDP and ADP‐β‐S gave ∼40% of the maximal response seen with ATP and UTP. Adenosine, AMP or α,β‐methylene‐ATP had no effect. These responses were attributed to P2Y2/4and P2Y1receptors, which we assumed could be selectively activated by UTP and ADP‐β‐S respectively.The response to UTP was reduced (∼50%) by pertussis toxin, whilst this toxin had no effect upon the response to ADP‐β‐S. This suggests P2Y2/4receptors simultaneously couple to pertussis toxin‐sensitive and ‐resistant G proteins whilst P2Y1receptors couple to only the toxin‐resistant proteins.Repeated stimulation with UTP or ADP‐β‐S caused desensitization which was potentiated by 12‐O‐tetradecanoyl phorbol‐13‐acetate (TPA) and attenuated by staurosporine.TPA completely abolished sensitivity to ADP‐β‐S but the response to UTP had a TPA‐resistant component. In pertussis toxin‐treated cells, however, TPA could completely abolish sensitivity to UTP and so the TPA‐resistant part of this response seems to be mediated by pertussis toxin‐sensitive G proteins.Loss of sensitivity to UTP did not occur when pertussis toxin‐treated cells were repeatedly stimulated with this nucleotide, suggesting that pertussis toxin‐sensitive G proteins mediate this effect. The toxin did not, however affect desensitization to ADP‐β‐S.British Journal of Pharmacology(1999)126, 1660–1666; doi:10.1038/sj.bjp.0702470
Effects of terbutaline on force and intracellular calcium in slow‐twitch skeletal muscle fibres of the rat
Authors: Ha Tuyen N V , Posterino Giuseppe S , Fryer Martin W 
Published: January 2005

The effect of the β2‐adrenoceptor agonist, terbutaline, was investigated on simultaneously measured force and intracellular free calcium ([Ca2+]i) in intact rat soleus muscle fibres, and on contractile protein function and Ca2+ content of the sarcoplasmic reticulum (SR) in skinned fibres.
Terbutaline (10 μM) had no significant effect on either resting force or [Ca2+]i. Exposure to terbutaline increased both the integral of the indo‐1 ratio transient and peak twitch force by 37%.
At sub‐maximal (10 Hz) stimulation frequencies, terbutaline accelerated force relaxation but had highly variable effects on tetanic force amplitude. The corresponding indo‐1 ratio transients were significantly larger, and faster to decay than the controls.
Terbutaline increased tetanic force at near maximal stimulation frequencies (50 Hz) by increasing tetanic [Ca2+]i. Force relaxation was accelerated at this frequency with no significant change in the indo‐1 ratio transient decay rate.
All of terbutaline's effects on force and indo‐1 ratio transients in intact fibres were completely blocked and reversed by ICI 118551 (1 μM).
Mechanically skinned fibres isolated from intact muscles pre‐treated with terbutaline showed no significant changes in SR Ca2+ content, myofilament [Ca2+]i‐sensitivity or maximum force generating capacity.
The results suggest that terbutaline primarily modulates force by altering the amplitude and decay rate of the [Ca2+]i transient via phosphorylation of both the ryanodine receptor (RR) and the SR pump regulatory protein, phospholamban (PLB). The high variability of responses of slow‐twitch muscles to β2‐agonists probably reflects individual differences in basal phosphorylation levels of PLB relative to that of RR.

British Journal of Pharmacology (1999) 126, 1717–1724; doi:10.1038/sj.bjp.0702482
Pilocarpine modulates the cellular electrical properties of mammalian hearts by activating a cardiac M3 receptor and a K+ current
Authors: Wang Huizhen , Shi Hong , Lu Yanjie , Yang Baofeng , Wang Zhiguo 
Published: January 2005

Pilocarpine, a muscarinic acetylcholine receptor (mAChR) agonist, is widely used for treatment of xerostomia and glaucoma. It can also cause many other cellular responses by activating different subtypes of mAChRs in different tissues. However, the potential role of pilocarpine in modulating cardiac function remained unstudied.
We found that pilocarpine produced concentration‐dependent (0.1–10 μM) decrease in sinus rhythm and action potential duration, and hyperpolarization of membrane potential in guinea‐pig hearts. The effects were nearly completely reversed by 1 μM atropine or 2 nM 4DAMP methiodide (an M3‐selective antagonist).
Patch‐clamp recordings in dispersed myocytes from guinea‐pig and canine atria revealed that pilocarpine induces a novel K+ current with delayed rectifying properties. The current was suppressed by low concentrations of M3‐selective antagonists 4DAMP methiodide (2–10 nM), 4DAMP mustard (4–20 nM, an ackylating agent) and p‐F‐HHSiD (20–200 nM). Antagonists towards other subtypes (M1, M2 or M4) all failed to alter the current.
The affinity of pilocarpine (KD) at mAChRs derived from displacement binding of [3H]‐NMS in the homogenates from dog atria was 2.2 μM (65% of the total binding) and that of 4DAMP methiodide was 2.8 nM (70% of total binding), consistent with the concentration of pilocarpine needed for the current induction and for the modulation of the cardiac electrical activity and the concentration of 4DAMP to block pilocarpine effects.
Our data indicate, for the first time, that pilocarpine modulates the cellular electrical properties of the hearts, likely by activating a K+ current mediated by M3 receptors.

British Journal of Pharmacology (1999) 126, 1725–1734; doi:10.1038/sj.bjp.0702486
Evidence for proteinase‐activated receptor‐2 (PAR‐2)‐mediated mitogenesis in coronary artery smooth muscle cells
Authors: Bretschneider Ellen , Kaufmann Roland , Braun Marina , Wittpoth Michael , Glusa Erika , Nowak Gotz , Schrör Karsten 
Published: January 2005

This study investigates, whether in addition to the thrombin receptor (PAR‐1), the proteinase‐activated receptor‐2 (PAR‐2) is present in vascular smooth muscle cells (SMC) and mediates mitogenesis. PAR‐2 is activated by low concentrations of trypsin and the synthetic peptide SLIGRL.
Stimulation of bovine coronary artery SMC by trypsin (2 nM) caused a 3 fold increase in DNLA‐synthesis. A similar effect was observed with 10 nM thrombin. Trypsin‐induced mitogenesis was inhibited by soybean trypsin inhibitor, indicating that the proteolytic activity of the enzyme was required for its mitogenic effect.
The specific PAR‐2‐activating peptide SLIGRL or the PAR1‐activating peptide SFFLRN did not elicit mitogenesis.
When the SMC were exposed to SLIGRL (40 nM), a homologous desensitization of cytosolic Ca2+ mobilization was found after subsequent stimulation with trypsin (40 nM) but not thrombin (15 nM).
Trypsin (2 nM) as well as SLIGRL (100 μM) activated the nuclear factor κB (NFκB) with a maximum response 2 h after stimulation of the SMC. This suggests that both agonists acted via a common receptor, PAR‐2. Maximum activation of NFκB by thrombin (10 nM) was detected after 4–5 h.
These data suggest that PAR‐2 is present in coronary SMC and mediates a mitogenic response. Activation of NFκB via either PAR‐1 or PAR‐2 does not predict mitogenesis.

British Journal of Pharmacology (1999) 126, 1735–1740; doi:10.1038/sj.bjp.0702509
Effects of A1‐adenosine receptor antagonists on purinergic transmission in the guinea‐pig vas deferens in vitro
Authors: Hardy Todd A , Brock James A 
Published: January 2005

Intracellularly recorded excitatory junction potentials (e.j.ps) were used to study the effects of adenosine receptor antagonists on neurotransmitter release from postganglionic sympathetic nerve terminals in the guinea‐pig vas deferens in vitro.
The A1 adenosine receptor antagonists, 8‐phenyltheophylline (10 μM) and 8‐cyclopentyl‐1,3‐dipropylxanthine (0.1 μM), increased the amplitude of e.j.ps evoked during trains of 20 stimuli at 1 Hz in the presence, but not in the absence, of the α2‐adrenoceptor antagonist, yohimbine (1 μM) or the non‐selective α‐adrenoceptor antagonist, phentolamine (1 μM).
Adenosine (100 μM) reduced the amplitude of e.j.ps, both in the presence and in the absence of phentolamine (1 μM). This inhibitory effect of adenosine is most likely caused by a reduction in transmitter release as there was no detectable change in spontaneous e.j.p. amplitudes.
In the presence of phentolamine, application of the adenosine uptake inhibitor, S‐(p‐nitrobenzyl)‐6‐thioinosine (0.1 μM), had no effect on e.j.p. amplitudes.
The phosphodiesterase inhibitor, 3‐isobutyl‐1‐methylxanthine (100 μM), significantly increased the amplitudes of all e.j.ps evoked during trains of 20 stimuli at 1 Hz, both in the presence and in the absence of phentolamine (1 μM).
These results suggest that endogenous adenosine modulates neurotransmitter release by an action at prejunctional A1 adenosine receptors only when α2‐adrenoceptors are blocked.

British Journal of Pharmacology (1999) 126, 1761–1768; doi:10.1038/sj.bjp.0702514
Recombinant human erythropoietin inhibits iNOS activity and reverts vascular dysfunction in splanchnic artery occlusion shock
Authors: Squadrito Francesco , Altavilla Domenica , Squadrito Giovanni , Campo Giuseppe M , Arlotta Mariarita , Quartarone Cristina , Saitta Antonino , Caputi Achille P 
Published: January 2005

We investigated the effects of recombinant human erythropoietin (rh‐EPO) in splanchnic artery occlusion (SAO) shock. Sham operated animals were used as controls. Survival rate, mean arterial blood pressure (MAP), serum Tumor Necrosis Factor (TNF‐α), plasma nitrite/nitrate concentrations, red blood cell (RBC) count, blood haemoglobin (Hb), the responsiveness of aortic rings to phenylephrine (PE, 1 nM–10 μM) and the activity of inducible nitric oxide synthase (iNOS) were studied.
SAO shocked rats had a decreased survival rate (0% at 4 h of reperfusion, while sham shocked rats survived more than 4 h), enhanced serum TNF‐α concentrations, increased plasma nitrite/nitrate levels (60±9.5 μM; sham shocked rats=2±0.4 μM), decreased MAP, unchanged RBC count and blood Hb and enhanced iNOS activity in the aorta. Moreover aortic rings from shocked rats showed a marked hyporeactivity to PE.
Rh‐EPO (25, 50 and 100 U 100 g−1, 5 min following the onset of reperfusion) increased survival rate (70% at 4 h of reperfusion with the highest dose), reduced plasma nitrite/nitrate concentrations (10.3±3.3 μM), increased MAP, did not change RBC count and blood Hb, and inhibited iNOS activity in thoracic aortae. Furthermore rh‐EPO, either in vivo or in vitro (10 U for 1 h in the organ bath), restored to control values the hyporeactivity to PE. Finally rh‐EPO inhibited the activity of iNOS in peritoneal macrophages activated with endotoxin.
Our data suggest that rh‐EPO protects against SAO shock by inhibiting iNOS activity.

British Journal of Pharmacology (1999) 127, 482–488; doi:10.1038/sj.bjp.0702521
Pharmacological analysis of CCK2 receptor antagonists using isolated rat stomach ECL cells
Authors: Lindström Erik , Björkqvist Maria , Håkanson Rolf 
Published: January 2005

Gastrin stimulates rat stomach ECL cells to secrete histamine and pacreastatin, a chromogranin A (CGA)‐derived peptide. The present report describes the effect of nine cholecystokinin2 (CCK2) receptor antagonists and one CCK1 receptor antagonist on the gastrin‐evoked secretion of pancreastatin from isolated ECL cells.
The CCK2 receptor antagonists comprised three benzodiazepine derivatives L‐740,093, YM022 and YF476, one ureidoacetamide compound RP73870, one benzimidazole compound JB 93182, one ureidoindoline compound AG041R and three tryptophan dipeptoids PD 134308 (CI988), PD135158 and PD 136450. The CCK1 receptor antagonist was devazepide.
A preparation of well‐functioning ECL cells (∼80% purity) was prepared from rat oxyntic mucosa using counter‐flow elutriation. The cells were cultured for 48 h in the presence of 0.1 nM gastrin; they were then washed and incubated with antagonist alone or with various concentrations of antagonist plus 10 nM gastrin (a maximally effective concentration) for 30 min. Gastrin dose‐response curves were constructed in the absence or presence of increasing concentrations of antagonist. The amount of pancreastatin secreted was determined by radioimmunoassay.
The gastrin‐evoked secretion of pancreastatin was inhibited in a dose‐dependent manner. YM022, AG041R and YF476 had IC50 values of 0.5, 2.2 and 2.7 nM respectively. L‐740,093, JB93182 and RP73870 had IC50 values of 7.8, 9.3 and 9.8 nM, while PD135158, PD136450 and PD134308 had IC50 values of 76, 135 and 145 nM. The CCK1 receptor antagonist devazepide was a poor CCK2 receptor antagonist with an IC50 of about 800 nM.
YM022, YF476 and AG041R were chosen for further analysis. YM022 and YF476 shifted the gastrin dose‐response curve to the right in a manner suggesting competitive antagonism, while the effects of AG041R could not be explained by simple competitive antagonism. pKB values were 11.3 for YM022, 10.8 for YF476 and the apparent pKB for AG041R was 10.4.

British Journal of Pharmacology (1999) 127, 530–536; doi:10.1038/sj.bjp.0702538
Selective inhibition of inducible nitric oxide synthase prevents ischaemic brain injury
Authors: Parmentier Sophie , Böhme Georg Andrees , Lerouet Dominique , Damour Dominique , Stutzmann Jean‐Marie , Margaill Isabelle , Plotkine Michel 
Published: January 2005

The aim of this study was to investigate the effect of N‐(3‐(aminomethyl)benzyl)acetamidine (1400W), a selective inhibitor of inducible calcium‐independent nitric oxide synthase (iNOS), on the functional and histopathological outcomes of experimental transient focal cerebral ischaemia in rats.
Transient ischaemia was produced by the occlusion for 2 h of both the left middle cerebral artery and common carotid artery. Treatments with 1400W (20 mg kg−1) or vehicle were started 18 h after occlusion of the arteries and consisted in seven subcutaneous injections at 8 h interval. Ischaemic outcomes and NOS activities (constitutive and calcium‐independent NOS) were evaluated 3 days after ischaemia.
1400W significantly reduced ischaemic lesion volume by 31%, and attenuated weight loss and neurological dysfunction.
1400W attenuated the calcium‐independent NOS activity in the infarct by 36% without affecting the constitutive NOS activity.
These findings suggest that iNOS activation contributes to tissue damage and that selective inhibitors of this isoform may be of interest for the treatment of stroke.

British Journal of Pharmacology (1999) 127, 546–552; doi:10.1038/sj.bjp.0702549
Comparative pharmacology of recombinant human M3 and M5 muscarinic receptors expressed in CHO‐K1 cells
Authors: Watson Nikki , Daniels Donald V , Ford Anthony P D W , Eglen Richard M , Hegde Sharath S 
Published: January 2005

Affinity estimates were obtained for several muscarinic antagonists against carbachol‐stimulated [3H]‐inositol phosphates accumulation in Chinese hamster ovary (CHO‐K1) cells stably expressing either human muscarinic M3 or M5 receptor subtypes. The rationale for these studies was to generate a functional antagonist affinity profile for the M5 receptor subtype and compare this with that of the M3 receptor, in order to identify compounds which discriminate between these two subtypes.
The rank order of antagonist apparent affinities (pKB) at the muscarinic M5 receptor was atropine (8.7)tolterodine (8.6)=4‐diphenylacetoxy‐N‐methylpiperidine (4‐DAMP, 8.6)>darifenacin (7.7)zamifenacin (7.6)>oxybutynin (6.6)=para‐fluorohexahydrosiladifenidol (p‐F‐HHSiD, 6.6)>pirenzepine (6.4)methoctramine (6.3)=himbacine (6.3)>AQ‐RA 741 (6.1).
Antagonist apparent affinities for both receptor subtypes compare well with published binding affinity estimates. No antagonist displayed greater selectivity for the muscarinic M5 subtype over the M3 subtype, but himbacine, AQ‐RA 741, p‐F‐HHSiD, darifenacin and oxybutynin displayed between 9‐ and 60 fold greater selectivity for the muscarinic M3 over the M5 subtype.
This study highlights the similarity in pharmacological profiles of M3 and M5 receptor subtypes and identifies five antagonists that may represent useful tools for discriminating between these two subtypes. Collectively, these data show that in the absence of a high affinity M5 selective antagonist, affinity data for a large range of antagonists is critical to define operationally the M5 receptor subtype.

British Journal of Pharmacology (1999) 127, 590–596; doi:10.1038/sj.bjp.0702551
Nitric oxide synthase inhibition by dimaprit and dimaprit analogues
Authors: Paquay Jos B G , 't Hoen Peter A Chr , Voss Hans‐Peter , Bast Aalt , Timmerman Henk , Haenen Guido R M M 
Published: January 2005

The similarity in molecular structure between the histamine H2‐agonist dimaprit (3‐dimethylamino‐propyl‐isothiourea) and the endogenous nitric oxide synthase (NOS) substrate L‐arginine prompted us to study the effect of dimaprit and some dimaprit analogues on NOS activity. Dimaprit and some of its analogues were tested in an in vitro assay which measures the conversion of [3H]‐L‐arginine to [3H]‐L‐citrulline. Dimaprit inhibits rat brain NOS (nNOS) concentration dependently with an IC50 of 49±14 μM.
Removal of one or both of the methyl groups from the non‐isothiourea nitrogen of dimaprit improved nNOS inhibitory properties. Aminopropylisothiourea is the most potent compound (IC50=4.1±0.9 μM) of the series followed by methylaminopropylisothiourea (IC50=7.6± μM).
The observed effect of aminopropylisothiourea and methylaminopropyl‐isothiourea are probably not due to the compounds themselves but to the corresponding mercaptoalkylguanidines, rearrangement products formed in aqueous solutions. This hypothesis is strengthened by the finding that aminobutylisothiourea is not active since a rearrangement to mercaptobutylguanidine does not occur.
Remarkably, nitrosylation of the isothiourea group of dimaprit decreases nNOS inhibitory activity, while nitrosylation of the guanidine analogue of dimaprit increases the inhibition of nNOS activity.
The pharmacological profile of dimaprit includes inhibition of nNOS. The nNOS inhibitory activity occurs in the same concentration range as the H2‐agonist and H3‐agonist activity of this compound.

British Journal of Pharmacology (1999) 127, 331–334; doi:10.1038/sj.bjp.0702552
Effect of insulin treatment on smooth muscle contractility and endothelium‐dependent relaxation in rat aortae from established STZ‐induced diabetes
Authors: Kobayashi Tsuneo , Kamata Katsuo 
Published: January 2005

This study involved the chronic administration of low or high insulin to rats with established streptozotocin (STZ)‐induced diabetes. We studied the effect of such treatment on smooth muscle contractility and endothelium‐dependent relaxation using aortic strips.
Aortae from diabetic rats, but not those from high‐insulin‐treated diabetic rats, showed an impaired endothelium‐dependent in response to acetylcholine (ACh) by comparison with untreated controls.
Isotonic high K+‐induced contractility was impaired in diabetic aortae. This impairment was prevented by high‐insulin treatment.
Noradrenaline (NA)‐induced contractility was enhanced in aortae from high‐insulin‐treated diabetic rats, but not in those from untreated diabetic or low‐insulin treated diabetic rats.
In the combined presence of the nitric oxide inhibitor NG‐nitro‐L‐arginine and the cyclo‐oxygenase inhibitor indomethacin, NA‐induced contractility was significantly greater in aortae from high‐insulin‐treated diabetic rats than in those from controls or untreated diabetic rats.
An increased expression of the mRNA for the α1D and α1B adrenergic receptors was found in aortae from high‐insulin‐treated diabetic rats.
These results demonstrate that in rats with established STZ‐induced diabetes, high‐insulin treatment prevents the development of an impaired endothelium‐dependent relaxation in the aorta, and that such treatment enhances NA‐induced contractility. This enhancement may be related to an upregulation in the expression of the mRNA for the α1B or α1D adrenergic receptor that is secondary to the hyperinsulinaemia.

British Journal of Pharmacology (1999) 127, 835–842; doi:10.1038/sj.bjp.0702554