bluuebunny/crossref_metadata_2025_split huggingface dataset:
Somatostatin receptors in Neuro2A neuroblastoma cells: operational characteristics
Authors: Koenig J A , Edwardson J M , Humphrey P P A 
Published: August 2006

We have used somatostatin (SRIF) receptor subtype‐selective ligands to determine some of the operational characteristics of somatostatin receptors in Neuro2A mouse neuroblastoma cells. The potent SRIF1‐receptor selective ligand, BIM‐23027, was able to displace completely the specific binding of radioiodinated somatostatin, [125I]‐Tyr11‐SRIF‐14, with a pIC50 of 10.3, suggesting that Neuro2A cells contain predominantly receptors of the SRIF1 receptor group. The rank order of affinities for several somatostatin analogues tested in competition studies, together with the high affinity of BIM‐23027, indicate that the majority of receptors in Neuro2A cells are of the sst2 subtype.
The stable radioligand, [125I]‐BIM‐23027, bound with high affinity (Kd=13 pm, Bmax=0.2 pmol mg−1 protein) to Neuro2A cell membranes, but its binding was only partially reversible at room temperature and below. Thus at 4°C, only 36% of the bound ligand dissociated within 2 h. In contrast, 60% of the ligand dissociated at 15°C and 89% of the ligand dissociated at 37°C.
Equilibrium binding of [125I]‐BIM‐23027 was partially (25%) inhibited by 10 μm GTP, and by 120 mm NaCl (42% inhibition) but this inhibition was increased to 75% when sodium chloride and GTP were added together. This effect of GTP and sodium chloride was also seen in dissociation experiments. After incubation to equilibrium with [125I]‐BIM‐23027, dissociation was initiated with excess unlabelled ligand in the presence of GTP (10 μm) and sodium chloride (120 mm). Under these conditions 67% of the ligand dissociated at 4°C, 81% at 15°C and 93% at 37°C. Binding was totally inhibited by pretreatment of cells with pertussis toxin.
Functionally, BIM‐23027 inhibited forskolin‐stimulated cyclic AMP accumulation in a concentration‐dependent manner with an IC50 of 1.0 nm and a maximal inhibition of 37%. This effect was abolished by pretreatment of the cells with pertussis toxin. However, unlike in studies reported with the recombinant sst2 receptor, no rise in intracellular calcium concentration was observed with SRIF‐14.
We conclude that Neuro2A cells provide a stable neuronal cell line for the study of functionally coupled endogenous somatostatin receptors of the sst2 type. In addition, we have found that activation of the receptor is associated with ligand‐receptor internalisation.

British Journal of Pharmacology (1997) 120, 45–51; doi:10.1038/sj.bjp.0700858
Inhibition by the immunosuppressive agent FK‐506 of antigen‐induced airways eosinophilia and bronchial hyperreactivity in mice
Authors: Eum Seok‐Yong , Zuany‐Amorium Claudia , Lefort Jean , Pretolani Marina , Vargaftig B Boris 
Published: August 2006

The effect of the immunosuppressive agent, FK‐506, on allergen‐induced airways eosinophilia and bronchial hyperreactivity (BHR) in hyper IgE mice (BP2 selection) was investigated.
Administration of FK‐506 at 2 mg kg−1 s.c., 1 h before and 5 h after the first of four ovalbumin challenges, reduced the recruitment of eosinophils into the bronchoalveolar lavage fluid (BALF) from 1.36±0.22×105 to 0.53±0.24×105 cells ml−1 (n=5–6, P<0.05; 60% inhibition), inhibited by 80% BHR in response to i.v. 5‐HT and practically suppressed BHR in response to inhaled methacholine.
The antigen‐induced interleukin (IL)‐5 formation in the BALF and serum was inhibited by FK‐506 by 75% in both instances.
FK‐506 failed to modify the bronchoconstriction in BP2 mice, suggesting that different mechanisms are involved in acute bronchoconstriction and BHR.
The increased number of CD4+, CD8+, CD3+ T lymphocytes in the BALF of antigen‐challenged mice was unaffected by FK‐506.
These findings indicate that antigen‐induced in vivo IL‐5 release and eosinophil, but not T‐cell, infiltration into the bronchial lumen of sensitized BP2 mice are targets for the anti‐allergic activities of FK‐506.

British Journal of Pharmacology (1997) 120, 130–136; doi:10.1038/sj.bjp.0700860
Lack of haemodynamic effects of nitric oxide on post‐capillary pulmonary hypertension induced by acute sino‐aortic denervation
Authors: Galinier Michel , Rougé Pierre , Fourcade Joëlle , Senard Jean‐Michel , Albenque Jean‐Paul , Balanescu Serban , Doazan Jean‐Philippe , Montastruc Jean‐Louis , Bounhoure Jean‐Paul , Montastruc Paul 
Published: August 2006

The aims of the present experiments were to define a new experimental model of pulmonary hypertension induced by a post‐capillary mechanism and to assess the haemodynamic effects of nitric oxide on post‐capillary pulmonary hypertension.
Cardiopulmonary variables of 28 male beagle dogs, anaesthetized with chloralose, 16 spontaneous breathing and 12 with assisted ventilation, were studied before and after sino‐aortic denervation (SAD). The haemodynamic effects of inhaled nitric oxide (25 p.p.m., 10 min), Nω‐nitro‐l‐arginine methyl ester (20 mg kg−1, i.v.), urapidil (0.5 mg kg−1, i.v.) and propranolol (300 μg kg−1, i.v.) were studied after SAD.
SAD induced an acute and transient pulmonary hypertension, more marked in spontaneous breathing dogs. This pulmonary hypertension involved a post‐capillary mechanism, secondary to the left ventricular haemodynamic effects of the acute increase of left ventricular after‐load induced by systemic hypertension. In fact, the increase of mean pulmonary arterial pressure after SAD and the decrease of this parameter after urapidil or propranolol were strongly correlated with the variations of pulmonary capillary wedge pressure. Furthermore, no significant change in pulmonary vascular resistances was found after SAD or administration of α or β‐adrenoceptor antagonists.
Inhaled nitric oxide did not reverse pulmonary hypertension induced by SAD. Nω‐nitro‐l‐arginine methyl ester had no significant haemodynamic effect on pulmonary circulation.
In conclusion, the lack of effect of inhaled nitric oxide and nitric oxide synthase inhibitor on pulmonary circulation parameters after SAD suggests that endothelium‐derived nitric oxide is not involved in the mechanisms leading to post‐capillary pulmonary hypertension.

British Journal of Pharmacology (1997) 120, 7–12; doi:10.1038/sj.bjp.0700864
Antagonist inhibition curves and the measurement of dissociation constants
Authors: Barlow R B , Bond Susan M , Bream Elizabeth , Macfarlane Lisa , McQueen D S 
Published: August 2006

Experiments carried out on guinea‐pig isolated ileum with carbachol as agonist and diphenyl‐ acetoxyethyl‐ dimethyl‐ethyl‐ ammonium (DADMEA) bromide as antagonist gave results which fit the theoretical relation between fractional inhibition (Q) of the effects of an agonist ([A]) and the concentration of a competitive antagonist ([B]): this also involves the Hill coefficient (logistic slope factor, P) for the agonist concentration‐response curve and the degree of agonist stimulation, [A]/[A]50, where [A]50 produces a half‐maximum response.
Values of IC50 and an exponent, P′, can be obtained by fitting Q to [B] using a logistic approximation to the relation. Both P′ and IC50 should be greater with higher agonist stimulation but the increase in P′ may be masked by errors in extreme values of Q. Estimates of IC50, however, invariably increased with higher agonist stimulation but with a steep concentration‐response curve (P>1) and low agonist stimulation ([A]/[A]50 <1), IC50 can be less than KD.
K
D was calculated from the results in three ways: (i) by a least‐squares fit of Q to [B] using the values of P and [A]/[A]50 calculated from the control concentration‐response curve; (ii) from the value of IC50 for each line and the values of P and [A]/[A]50 and (iii) by using the agonist concentration‐response curve to calculate the dose‐ratio and estimate of KD for each response in the presence of the antagonist. The methods gave similar results (nm: 11 experiments), 12.4±1.1 (i), 11.7±0.9 (ii), 14.8±1.6 (iii) but there are advantages in using methods (i) or (ii) rather than (iii).
The method by which KD is calculated is less important than the experimental design: the plan used in this work, with alternative small and large responses from the tissue, is very suitable for estimating KD with low concentrations of antagonists and small dose‐ratios. Although it is not a sensitive test for competitive behaviour because only a small range of concentrations of antagonist is tested, the estimate of affinity should be free from complications involved in the use of higher concentrations of antagonist (and agonist) and the nature of the antagonism can always be checked by doing further experiments in the presence of a known competitive antagonist.

British Journal of Pharmacology (1997) 120, 13–18; doi:10.1038/sj.bjp.0700865
Depressant effects of hypoxia and hypoglycaemia on neuro‐effector transmission of guinea‐pig intestine studied in vitro with a pharmacological model
Authors: Corbett A D , Lees G M 
Published: August 2006

Since intermittent ischaemia may play an important role in the ætiology of Inflammatory Bowel Disease, particularly Crohn's Disease, a pharmacological model of neuronal ischaemia was applied to guinea‐pig isolated intestinal preparations to mimic the acute effects of reduced blood flow on intestinal motility.
Neuro‐effector transmission and smooth muscle performance were examined in myenteric plexus‐longitudinal muscle preparations of guinea‐pig ileum exposed to sodium cyanide (NaCN), in order to inhibit oxidative phosphorylation, or to iodoacetic acid (IAA), to block glycolysis. Comparisons were made with the effects due to simple deprivation of oxygen or glucose.
Depressions of cholinergic neuro‐effector transmission induced by hypoxia or NaCN (effective concentration range 0.1–3 mm), given as separate treatments, singly or repetitively over 60–90 min, were apparent within 30 s and were reversible. The maximum inhibition was 90% and the IC50 for NaCN was 0.3 mm. A conspicuous component of these inhibitions was prejunctional.
Non‐cholinergic neuro‐effector contractions were inhibited by up to 90% by anoxia or NaCN but recovery was incomplete and slower than with cholinergic contractions.
Glucose‐free solutions also caused a reversible failure of cholinergic neuro‐effector transmission but of slower onset. In contrast, IAA (0.06–1 mm) abolished contractions irreversibly, apparently by a direct depressant effect on smooth muscle contraction. Unlike NaCN, IAA caused an initial potentiation of electrically‐induced contractions, partly by a prejunctional potentiation of cholinergic neuro‐effector transmission.
It is concluded that a disruption of intestinal activity in pathological conditions associated with intestinal ischaemia may result from disturbances in the function of enteric neurones.

British Journal of Pharmacology (1997) 120, 107–115; doi:10.1038/sj.bjp.0700870
Electrophysiological effects of CI‐980, a tubulin binding agent, on guinea‐pig papillary muscles
Authors: Pérez Onésima , Valenzuela Carmen , Delpón Eva , Tamargo Juan 
Published: August 2006

The electrophysiological effects of CI‐980, a new tubulin‐binding agent that inhibits assembly of cytoplasmic microtubules, on transmembrane action potential characteristics were studied in right ventricular papillary muscles from guinea‐pig hearts.
In papillary muscles driven at 1 Hz, CI‐980 at concentrations 10−5 m produced a concentration‐dependent increase in the maximum upstroke velocity (Vmax) and a lengthening of the action potential duration at 50% (APD50) and 90% (APD90) of repolarization without affecting the resting membrane potential. Prolongation of the APD90 was accompanied by a parallel lengthening of the effective refractory period (ERP) so that the ERP/APD90 ratio remained unaltered at all drug concentrations tested.
CI‐980 exhibits a reverse use‐dependent effect on APD90 values, that is, drug‐induced APD90 prolongation become exagerated at slow rates and attenuated at fast rates.
CI‐980 at concentrations 10−6 m lengthened the APD of the slow action potentials elicited by isoprenaline in papillary muscles depolarized by high K+ (27 mm) solution.
At 10−5 m, CI‐980 produced a small tonic Vmax block. However, in muscles driven at rates between 0.5 and 3 Hz it produced an exponential decline in Vmax (use‐dependent Vmax block) which was augmented at higher rates of stimulation. At 3 Hz the onset kinetics of the use‐dependent Vmax block was fitted by a monoexponential function with a K value 0.07±0.01 per AP. The recovery time constant (τre) from the use‐dependent Vmax block was prolonged from 21.6±2.6 ms to 3.5±0.2 s.
The curve relating membrane potential and Vmax was shifted by CI‐980 (10−5 m) in the hyperpolarizing direction by 2.3±1.1 mV.
It is concluded that in guinea‐pig papillary muscles, CI‐980 produces a use‐dependent inhibition of Vmax and a reverse use‐dependent prolongation of the ventricular action potential, thus exhibiting class I and class III antiarrhythmic actions, respectively. From the onset and offset kinetics of use‐dependent Vmax block, CI‐980 can be considered to be an intermediate kinetics (IA) Na+ channel blocker.

British Journal of Pharmacology (1997) 120, 187–192; doi:10.1038/sj.bjp.0700878
Contribution of adrenal hormones to nicotine‐induced inhibition of synovial plasma extravasation in the rat
Authors: Jia‐Pei Miao Frederick , Benowitz Neal L , Heller Philip H , Levine Jon D 
Published: August 2006

In this study, we examined the mechanism(s) by which s.c. nicotine inhibits synovial plasma extravasation. We found that nicotine dose‐dependently inhibited bradykinin (BK)‐ and platelet activating factor (PAF)‐induced plasma extravasation.
The effect of nicotine on both BK‐ and PAF‐induced plasma extravasation was attenuated by adrenal medullectomy. ICI‐118,551 (a selective β2‐adrenoceptor blocker) (30 μg ml−1, intra‐articularly) significantly attenuated the inhibitory action of high‐dose (1 mg kg−1) nicotine on BK‐induced plasma extravasation without affecting the inhibition by low‐ (0.01 μg kg−1) dose nicotine or that on PAF‐induced plasma extravasation by nicotine at any dose. This suggested that β2‐adrenoceptors mediate the inhibitory actions of high‐dose, but not low‐dose, nicotine. We also found that systemic naloxone (an opioid receptor antagonist) (two hourly injections of 1 mg kg−1, i.p.) attenuated the inhibitory action produced by all doses of nicotine on BK‐ or PAF‐induced plasma extravasation, suggesting the contribution of endogenous opioids.
RU‐38,486 (a glucocorticoid receptor antagonist) (30 mg kg−1, s.c.) and metyrapone (a glucocorticoid synthesis inhibitor) (two hourly injections of 100 mg kg−1, i.p.) both attenuated the action of high‐dose nicotine without affecting that of low‐dose nicotine.
Spinal mecamylamine (a nicotinic receptor antagonist) (0.025 mg kg−1, intrathecally, i.t.) attenuated the action of high‐dose, but not low‐dose, nicotine, suggesting that part of the action of high‐dose nicotine is mediated by spinal nicotinic receptors.
Combined treatment with ICI‐118,551, naloxone and RU‐38,486 attenuated the action of low‐dose nicotine by an amount similar to that produced by naloxone alone but produced significantly greater attenuation of the effect of high‐dose nicotine when compared to the action of any of the three antagonists alone.

British Journal of Pharmacology (1997) 120, 298–304; doi:10.1038/sj.bjp.0700884
Selective block of N‐methyl‐d‐aspartic acid (NMDA)‐evoked whole‐cell currents in mouse cultured spinal neurones by CGP 40116
Authors: D'Hooge R , Raes A , Van Bogaert P P , Geelhand M , De Deyn P P 
Published: August 2006

CGP 40116 is the active (R)‐enantiomer of the most potent N‐methyl‐d‐aspartic acid (NMDA) receptor antagonist presently available: 2‐amino‐4‐methyl‐5‐phosphono‐3‐pentenoic acid (CGP 37849). In this study, we describe the effect of CGP 40116 on whole‐cell currents induced by excitatory amino acids in cultured mouse spinal cord cells by use of the whole‐cell patch‐clamp technique.
We found that application of CGP 40116 in the nm range, concentration‐dependently inhibited whole‐cell current evoked by 20 μm NMDA in mouse cultured spinal neurones (IC50±s.e.mean 48±8 nm CGP 40116).
The compound appeared to be highly selective for the NMDA current. At concentrations as high 1 μm, currents evoked by α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionic acid (AMPA) or kainic acid were not affected by CGP 40116. The threshold concentration for antagonism of NMDA‐induced responses was 10 nm suggesting a selectivity ratio of 100 fold for NMDA receptors versus AMPA or kainate receptors.
CGP 40116 produced a parallel rightward displacement of the NMDA log concentration‐current curve indicating competitive antagonism at the transmitter recognition site of the NMDA receptor complex. An apparent dissociation constant for the antagonist was calculated from the displacement of the agonist concentration‐current curve: 117±53 nm CGP 40116 (estimated Kd±s.e.). Like other competitive NMDA antagonists, CGP 40116 blocked NMDA‐evoked current in a voltage‐independent manner.

British Journal of Pharmacology (1997) 120, 211–214; doi:10.1038/sj.bjp.0700886
In vitro and in vivo effects of UP 269‐6, a new potent orally active nonpeptide angiotensin II receptor antagonist, on vascular smooth muscle cell proliferation
Authors: Virone‐Oddos A. , Desangle V. , Provost D. , Cazes M. , Caussade F. , Cloarec A. 
Published: August 2006

The present studies were designed to measure the affinity of UP 269‐6, a newly developed angiotensin AT1 receptor antagonist, for vascular AT1 receptors from normotensive and hypertensive rats and to investigate in vitro, its effects on angiotensin II (AII)‐induced hyperplasia and hypertrophy of vascular smooth muscle cells (VSMC). In addition the in vivo effects of UP 269‐6 on neointimal proliferation in a carotid artery balloon injury in normotensive rats were also investigated.
UP 269‐6 selectively inhibited [125I]‐Sar1‐Ile8‐AII binding to vascular AT1 receptors present on VSMC derived from normotensive Wistar rat and from SHR (Ki= 16.6 ± 3.6 nM and 7.5 ± 2.0 nM, respectively). In comparison, losartan and its metabolite, EXP 3174, inhibited [125I‐Sar1‐Ile8‐AII binding to vascular AT1 receptors derived from both cell models with Ki values slightly lower (losartan) and higher (EXP 3174), respectively, than that of UP 269‐6.
AII (1 μM) induced a weak and variable hyperplastic response (4 to 32% increase in cell number) in Wistar rat VSMC after 96 h.
AII (1 μM) induced a time‐dependent increase in cell number in VSMC from SHR. UP 269‐6 inhibited concentration‐dependently this effect with an IC50 value of 159 ± 58 nM. Losartan was clearly less potent and EXP 3174 showed nearly the same inhibitory potency, compared to UP 269‐6. UP 269‐6 (1 μm) inhibited nearly completely the action of AII.
AII (500 nM) caused maximal stimulation of protein synthesis in Wistar rat VSMC (117 ± 36%). UP 269‐6, losartan and EXP 3174 totally inhibited this stimulation with IC50 values of 28 ± 6 nM, 3504 ± 892 nM and 21±3 nM, respectively.
AII (50 nM) induced maximal stimulation of protein synthesis in SHR VSMC (237 ± 67%). UP 269‐6, losartan and EXP 3174 totally inhibited this stimulation with IC50 values of 16 ± 3 nM, 282± 122 nM and 3.3 ± 1.0 nM, respectively.
UP 269‐6 (75 mg kg−1 day−1) administered orally in the diet for 20 days induced a 38% reduction in neointimal area and a 36% reduction in neointima/media ratio associated with the intimal thickening induced by carotid artery balloon injury.
In conclusion, UP 269‐6 was shown to be a potent antiproliferative agent both in vitro on AII‐induced hyperplasia and hypertrophy of VSMC derived from normotensive and hypertensive rats, and in vivo upon intimal thickening induced by carotid artery balloon injury in the rat.
Bradykinin‐induced contractions of canine saphenous veins: mediation by B2 receptors and involvement of eicosanoids
Authors: Marsault Robert , Illiano Stéphane , Vanhoutte Paul M 
Published: August 2006

Experiments were designed to determine the subtype of kinin‐receptors mediating the contraction of venous smooth muscle to bradykinin and to investigate the involvement of metabolites of arachidonic acid in this response.
Bradykinin (10−9 to 10−6 m) caused concentration‐dependent contractions of the canine isolated saphenous vein without endothelium, which were potentiated by indomethacin (10−5 m, an inhibitor of cyclo‐oxygenase). The concentration‐response curve was biphasic, reaching an asymptote at 10−8 m and a secondary maximal response at 10−6 m.
Bradykinin (10−8 m to 3×10−6 m) caused a three fold stimulation in the release of the vasodilator prostaglandin E2 (PGE2) and a two fold stimulation of that of the vasodilator prostacyclin, measured by the production of 6‐keto‐PGF1α (its stable breakdown product).
Under control conditions, nordihydroguaiaretic acid (NDGA, 10−5 m), an inhibitor of lipoxygenase, did not affect the response to bradykinin. In the presence of indomethacin (10−5 m), NDGA reduced contractions to bradykinin, suggesting the involvement of lipoxygenase metabolites in the potentiation evoked by the inhibitor of cyclo‐oxygenase.
The selective B1 receptor agonist [des‐Arg9]‐bradykinin, in the concentration‐range 10−6 to 10−5 m, induced contractions, which were abolished by the B2 receptor antagonist d‐Arg‐[Hyp3,Thi5,d‐Tic7,Oic8]‐bradykinin (Hoe 140, 10−6 m). The selective B1 receptor antagonist [des‐Arg9,Leu8]‐bradykinin, (10−7 to 10−5 m) had no significant effect on bradykinin‐induced contractions.
The B2 receptor antagonists Hoe 140 (10−8 to 10−6 m) and d‐Arg[Hyp3,d‐Phe7]‐bradykinin (10−7 to 10−5 m) shifted the concentration‐response curve to bradykinin to the right in a concentration‐dependent manner.
These results indicate that, in the canine saphenous vein, bradykinin causes contraction by activating B2 receptors. This results in the production of metabolites of arachidonic acid, which play a key role in the contraction of canine saphenous venous smooth muscle.

British Journal of Pharmacology (1997) 120, 215–220; doi:10.1038/sj.bjp.0700898