bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of the beta2 adrenoceptor gene Thr164Ile polymorphism on human adipose tissue lipolytic function
Authors: Hoffstedt Johan , Iliadou Anastasia , Pedersen Nancy L , Schalling Martin , Arner Peter 
Published: January 2005

A rare β2‐adrenoceptor gene polymorphism, Thr164Ile, has been described that impairs receptor function when transfected into cell lines. We investigated whether the polymorphism influences native receptor function by studying lipolysis in freshly isolated subcutaneous fat cells from 236 apparently healthy subjects.
Twelve subjects were heterozygous for the 164Ile variant. The fat cells of Ile carriers displayed a 6 fold increase (P=0.02) in the lipolytic EC50 of terbutaline (a selective β2‐adrenoceptor agonist), but no change in the lipolytic action of dobutamine (a selective β1‐adrenoceptor agonist), compared with the Thr carriers. Maximum adrenoceptor agonist stimulated lipolysis did not differ between Thr and Ile carriers.
The influence of two other polymorphisms (Arg16Gly and Gln27Glu) in the β2‐adrenoceptor gene was considered. Six 164Ile carriers also carried the 16Gly and 27Glu alleles. The latter combination occurred among 105 of the 164Thr carriers. For the 16Gly27Glu subgroup, the EC50 of terbutaline was about 10 fold higher in 164Ile as than in 164Thr carriers (P=0.02) but there was no difference between genotypes in maximum terbutaline action. There was no difference between groups in dobutamine action.
In conclusion, the 164Ile variant of the β2‐adrenoceptor is associated with a decreased native adipocyte receptor function, as evidenced by a marked increase in the half maximal effective concentration of the lipolytic action of a selective β2‐adrenoceptor agonist. This suggests that genetic variance in the β2‐adrenoceptor gene might be important for catecholamine function in humans, at least as far as adipocyte lipolysis is concerned.

British Journal of Pharmacology (2001) 133, 708–712; doi:10.1038/sj.bjp.0704125
Effect of cyclosporin A and its vehicle on cardiac and skeletal muscle mitochondria: relationship to efficacy of the respiratory chain
Authors: Sanchez H , Zoll J , Bigard X , Veksler V , Mettauer B , Lampert E , Lonsdorfer J , Ventura‐Clapier R 
Published: January 2005

Although cyclosporin (CsA) is considered to be the best immunosuppressive molecule in transplantation, it has been suspected to alter mitochondrial respiration of various tissues.
We evaluated the acute effect of CsA and its vehicle on maximal oxidative capacity (Vmax) of cardiac, soleus and gastrocnemius muscles of rats by an oxygraphic method in saponin skinned muscle fibres. The effects of Sandimmun (a formulation of CsA), vehicle of Sandimmun (cremophor and ethanol (EtOH)), CsA in EtOH and EtOH alone were tested. Increasing concentrations (5 – 20 – 50 – 100 μM) of CsA (or vehicles) were used.
Sandimmun profoundly altered the Vmax of all muscles. For example, at 20 μM, inhibition reached 18±3, 23±5, 45±5%, for heart, soleus and gastrocnemius respectively. There were only minor effects of CsA diluted in EtOH and EtOH alone on Vmax of cardiac muscle. Because the effects of vehicle on Vmax were similar or higher than those of Sandimmun, the inhibition of oxidative capacity could be entirely attributed to the vehicle for all muscles.
Next, we investigated the potential sites of action of the vehicle on the different complexes of the mitochondrial respiratory chain by using specific substrates and inhibitors. The vehicle affected mitochondrial respiration mainly at the level of complex I (∼−85% in skeletal muscles, and −32% in heart), but also at complex IV (∼−26% for all muscles).
The mechanism of action of the vehicle on the mitochondrial membrane and the implications for the clinical use of immunosuppressive drugs are discussed.

British Journal of Pharmacology (2001) 133, 781–788; doi:10.1038/sj.bjp.0704129
Reversal of cardiac and renal fibrosis by pirfenidone and spironolactone in streptozotocin‐diabetic rats
Authors: Miric Goran , Dallemagne Catherine , Endre Zoltan , Margolin Solomon , Taylor Stephen M , Brown Lindsay 
Published: January 2005

Fibrosis leads to chronic impairment of cardiac and renal function and thus reversal of existing fibrosis may improve function and survival. This project has determined whether pirfenidone, a new antifibrotic compound, and spironolactone, an aldosterone antagonist, reverse both deposition of the major extracellular matrix proteins, collagen and fibronectin, and functional changes in the streptozotocin(STZ)‐diabetic rat.
Streptozotocin (65 mg kg−1 i.v.)‐treated rats given pirfenidone (5‐methyl‐1‐phenyl‐2‐[1H]‐pyridone; approximately 200 mg kg−1 day−1 as 0.2–2g 1−1 drinking water) or spironolactone (50 mg kg−1 day−1 s.c.) for 4 weeks starting 4 weeks after STZ showed no attenuation of the increased blood glucose concentrations and increased food and water intakes which characterize diabetes in this model.
STZ‐treatment increased perivascular and interstitial collagen deposition in the left ventricle and kidney, and surrounding the aorta. Cardiac, renal and plasma fibronectin concentrations increased in STZ‐diabetic rats. Passive diastolic stiffness increased in isolated hearts from STZ‐diabetic rats. Both pirfenidone and spironolactone treatment attenuated these increases without normalizing the decreased +dP/dtmax of STZ‐diabetic hearts.
Left ventricular papillary muscles from STZ‐treated rats showed decreased maximal positive inotropic responses to noradrenaline, EMD 57033 (calcium sensitizer) and calcium chloride; this was not reversed by pirfenidone or spironolactone treatment. STZ‐treatment transiently decreased GFR and urine flow rates in isolated perfused kidneys; pirfenidone but not spironolactone prevented the return to control values.
Thus, short‐term pirfenidone and spironolactone treatment reversed cardiac and renal fibrosis and attenuated the increased diastolic stiffness without normalizing cardiac contractility or renal function in STZ‐diabetic rats.

British Journal of Pharmacology (2001) 133, 687–694; doi:10.1038/sj.bjp.0704131
Characterization of ionotropic glutamate receptors in human lymphocytes
Authors: Lombardi Grazia , Dianzani Chiara , Miglio Gianluca , Canonico Pier Luigi , Fantozzi Roberto 
Published: January 2005

The effect of L‐glutamate (Glu) on human lymphocyte function was studied by measuring anti‐CD3 monoclonal antibody (mAb) or phytohaemagglutinin (PHA)‐induced intracellular Ca2+ ([Ca2+]i) rise (Fura‐2 method), and cell proliferation (MTT assay).
Glu (0.001 – 100 μM) did not modify basal lymphocyte [Ca2+]i, but significantly potentiated the effects of anti‐CD3 mAb or PHA. Maximal [Ca2+]i rises over resting cells were: 165±8 and 247±10 nM at 3.0×10−2 mg ml−1 anti‐CD3 mAb; 201±4 and 266±9 nM at 5.0×10−2 mg ml−1 PHA, in the absence or presence of 1 μM Glu, respectively.
The Glu effect showed a bell‐shape concentration‐dependent relationship, with a maximum (+90±3% for anti‐CD3 mAb and +57±2% for PHA over Glu‐untreated cells) at 1 μM.
Non‐NMDA receptor agonists (1 μM) showed a greater efficacy (+76±2% for (S)‐AMPA; +78±4% for KA), if compared to NMDA (+46±2%), or Glu itself.
Ionotropic Glu receptor antagonists completely inhibited the effects of the corresponding specific receptor agonists (1 μM). The IC50 values calculated were: 0.9 μM for D‐AP5; 0.6 μM for (+)‐MK801; 0.3 μM for NBQX. Both NBQX and KYNA were able to abolish Glu effect. The IC50s calculated were: 3.4 μM for NBQX; 0.4 μM for KYNA.
Glu (0.1 – 1 mM) did not change the resting cell proliferation, whereas Glu (1 mM) significant inhibited (−27±4%) PHA (1.0×10−2 mg ml−1)‐induced lymphocyte proliferation at 72 h.
In conclusion, human lymphocytes express ionotropic Glu receptors functionally operating as modulators of cell activation.

British Journal of Pharmacology (2001) 133, 936–944; doi:10.1038/sj.bjp.0704134
Evidence that ET‐1, but not ET‐3 and S6b, ETA‐receptor mediated contractions in isolated rat mesenteric arteries are modulated by co‐activation of ETB receptors
Authors: Adner Mikael , Shankley Nigel , Edvinsson Lars 
Published: January 2005

The effects of agonists with endothelin (ET) ETA‐receptor activity have been analysed in relation to their interaction with ETB receptors in rat mesenteric arteries.
ET‐1, sarafotoxin 6b (S6b) and ET‐3 induced large, slow‐onset and sustained contractions whereas S6c induced weak transient contractions. However, following pre‐contraction with U46619 and subsequent relaxation with forskolin, the effect of S6c was amplified, indicating a potential for powerful ETB‐receptor mediated contraction.
The selective ETA‐receptor antagonist, FR139317, produced parallel rightward shifts of ET‐1, S6b and ET‐3 concentration‐effect curves indicating that the contractions were mediated by ETA receptors. However, the corresponding FR139317 pKB values were significantly different between the agonists. As expected FR139317 had no effect on S6c responses.
Pre‐treatment with S6c to desensitize ETB receptors, increased ET‐1 potency and the pKB value for FR139317. In contrast, neither the potency of S6b and ET‐3 nor the pKB values for FR139317 estimated using these agonists were affected by ETB‐receptor desensitization.
Segments pre‐contracted with submaximal concentrations of S6b and ET‐3, but not ET‐1, rapidly relaxed following wash‐out or FR139317 administration.
The results indicate that the small contractile response to selective ETB receptor activation, barely detectable under standard bioassay conditions, is greatly amplified when adenylate cyclase activity is elevated. Moreover, the response to ETA receptor activation by ET‐1, but not ET‐3 and S6b, is significantly modified by co‐activation of ETB receptors. This interaction has a significant effect on the apparent affinity of ETA‐receptor selective antagonists when ET‐1 is used as agonist and decreases the potency of ET‐1.

British Journal of Pharmacology (2001) 133, 927–935; doi:10.1038/sj.bjp.0704135
Role of opioid receptors in neurogenic dural vasodilation and sensitization of trigeminal neurones in anaesthetized rats
Authors: Williamson D J , Shepheard S L , Cook D A , Hargreaves R J , Hill R G , Cumberbatch M J 
Published: January 2005

Migraine headache is thought to be caused by a distension of meningeal blood vessels, the activation of trigeminal sensory neurones and the the development of a central sensitization within the trigeminal nucleus caudalis (TNC). It has been proposed that clinically effective 5‐HT1B/1D agonists act peripherally to inhibit the release of calcitonin gene‐related peptide (CGRP) and neurogenic dural vasodilation, and to attenuate nociceptive neurotransmission within the TNC. Since opioids are also effective anti‐migraine agents the present studies investigated the role of opioids within the trigemino‐vascular system in anaesthetised rats.
Electrical stimulation of the dura mater evoked neurogenic dural vasodilation which was significantly inhibited by morphine (1 mg kg−1) the selective μ‐opioid agonist DAGO (10 μg kg−1) and the mixed agonist/antagonist butorphanol (1 mg kg−1) but not by the κ‐ and δ‐opioid agonists (±) U50488H (100 μg kg−1) and DPDPE (1 mg kg−1). Morphine had no effect on CGRP‐evoked dural vasodilation.
In electrophysiological studies morphine (1 – 10 mg kg−1) significantly attenuated brainstem neuronal activity in response to electrical stimulation of the dura by 65% at 10 mg kg−1. Morphine (3 mg kg−1) also inhibited the TNC neuronal sensitization following CGRP‐evoked dilation.
The present studies have demonstrated that opioids block the nociceptive neurotransmission within the trigeminal nucleus caudalis and in addition inhibit neurogenic dural vasodilation via an action on μ‐opioid receptors located on trigeminal sensory fibres innervating dural blood vessels. These peripheral and central actions are similar to those of the ‘triptan’ 5‐HT1B/1D agonists and could account for the anti‐migraine actions of opioids.

British Journal of Pharmacology (2001) 133, 807–814; doi:10.1038/sj.bjp.0704136
A microdialysis study of the novel antiepileptic drug levetiracetam: extracellular pharmacokinetics and effect on taurine in rat brain
Authors: Tong X , Patsalos P N 
Published: January 2005

Using a rat model which allows serial blood sampling and concurrent brain microdialysis sampling, we have investigated the temporal kinetic inter‐relationship of levetiracetam in serum and brain extracellular fluid (frontal cortex and hippocampus) following systemic administration of levetiracetam, a new antiepileptic drug. Concurrent extracellular amino acid concentrations were also determined.
After administration (40 or 80 mg kg−1), levetiracetam rapidly appeared in both serum (Tmax, 0.4 – 0.7 h) and extracellular fluid (Tmax, 2.0 – 2.5 h) and concentrations rose linearly and dose‐dependently, suggesting that transport across the blood‐brain barrier is rapid and not rate‐limiting. The serum free fraction (free/total serum concentration ratio; mean±s.e.mean range 0.93 – 1.05) was independent of concentration and confirms that levetiracetam is not bound to blood proteins.
The kinetic profiles for the hippocampus and frontal cortex were indistinguishable suggesting that levetiracetam distribution in the brain is not brain region specific. However, t1/2 values were significantly larger than those for serum (mean range, 3.0 – 3.3 h vs 2.1 – 2.3 h) and concentrations did not attain equilibrium with respect to serum.
Levetiracetam (80 mg kg−1) was associated with a significant reduction in taurine in the hippocampus and frontal cortex. Other amino acids were unaffected by levetiracetam.
Levetiracetam readily and rapidly enters the brain without regional specificity. Its prolonged efflux from and slow equilibration within the brain may explain, in part, its long duration of action. The concurrent changes in taurine may contribute to its mechanism of action.

British Journal of Pharmacology (2001) 133, 867–874; doi:10.1038/sj.bjp.0704141
Sirolimus, but not the structurally related RAD (everolimus), enhances the negative effects of cyclosporine on mitochondrial metabolism in the rat brain
Authors: Serkova Natalie , Jacobsen Wolfgang , Niemann Claus U , Litt Lawrence , Benet Leslie Z , Leibfritz Dieter , Christians Uwe 
Published: January 2005

Clinical studies have shown enhancement of cyclosporine toxicity when co‐administered with the immunosuppressant sirolimus. We evaluated the biochemical mechanisms underlying the sirolimus/cyclosporine interaction on rat brain metabolism using magnetic resonance spectroscopy (MRS) and compared the effects of sirolimus with those of the structurally related RAD.
Two‐week‐old rats (25 g) were allocated to the following treatment groups (all n=6): I. control, II. cyclosporine (10 mg kg−1 d−1), III. sirolimus (3 mg kg−1 d−1), IV. RAD (3 mg kg−1 d−1), V. cyclosporine+sirolimus and VI. cyclosporine+RAD. Drugs were administered by oral gavage for 6 days. Twelve hours after the last dose, metabolic changes were assessed in brain tissue extracts using multinuclear MRS.
Cyclosporine significantly inhibited mitochondrial glucose metabolism (glutamate: 78±6% of control; GABA: 67±12%; NAD+: 76±3%; P<0.05), but increased lactate production. Sirolimus and RAD inhibited cytosolic glucose metabolism via lactate production (sirolimus: 81±3% of control, RAD: 69±2%; P<0.02). Sirolimus enhanced cyclosporine‐induced inhibition of mitochondrial glucose metabolism (glutamate: 60±4%; GABA: 59±8%; NAD+: 45±5%; P<0.02 versus cyclosporine alone). Lactate production was significantly reduced. In contrast, RAD antagonized the effects of cyclosporine (glutamate, GABA, and NAD+, not significantly different from controls).
The results can partially be explained by pharmacokinetic interactions: co‐administration increased the distribution of cyclosporine and sirolimus into brain tissue, while co‐administration with RAD decreased cyclosporine brain tissue concentrations. In addition RAD, but not sirolimus, distributed into brain mitochondria.
The combination of cyclosporine/RAD compares favourably to cyclosporine/sirolimus in regards to their effects on brain high‐energy metabolism and tissue distribution in the rat.

British Journal of Pharmacology (2001) 133, 875–885; doi:10.1038/sj.bjp.0704142
Inhibition of poly (ADP‐ribose) synthetase by gene disruption or inhibition with 5‐iodo‐6‐amino‐1,2‐benzopyrone protects mice from multiple‐low‐dose‐streptozotocin‐induced diabetes
Authors: Mabley Jon G , Suarez‐Pinzon Wilma L , Haskó György , Salzman Andrew L , Rabinovitch Alex , Kun Ernest , SzabÓ Csaba 
Published: January 2005

Activation of poly(ADP‐ribose) synthetase (PARS, also termed polyADP‐ribose polymerase or PARP) has been proposed as a major mechanism contributing to β‐cell destruction in type I diabetes. In the present study, we have investigated the role of PARS in mediating the induction of diabetes and β‐cell death in the multiple‐low‐dose‐streptozotocin (MLDS) model of type I diabetes.
Mice genetically deficient in PARS were found to be less sensitive to MLDS than wild type mice, with a lower incidence of diabetes and reduced hyperglycemia.
A potent inhibitor of PARS, 5‐iodo‐6‐amino‐1,2‐benzopyrone (INH2BP), was also found to protect mice from MLDS and prevent β‐cell loss, in a dose‐dependent manner. Paradoxically, in the PARS deficient mice, the compound increased the onset of diabetes.
In vitro the cytokine combination; interleukin‐1β, tumor necrosis factor‐α and interferon‐γ inhibited glucose‐stimulated insulin secretion from isolated rat islets of Langerhans and decreased RIN‐5F cell viability. The PARS inhibitor, INH2BP, protected both the rat islets and the β‐cell line, RIN‐5F, from these cytokine‐mediated effects. These protective effects were not mediated by inhibition of cytokine‐induced nitric oxide formation.
Inhibition of PARS by INH2BP was unable to protect rat islet cells from cytokine‐mediated apoptosis.
Cytokines, peroxynitrite and streptozotocin were all shown to induce PARS activation in RIN‐5F cells, an effect suppressed by INH2BP.
The present study provides evidence for in vivo PARS activation contributing to β‐cell damage and death in the MLDS model of diabetes, and indicates a role for PARS activation in cytokine‐mediated depression of insulin secretion and cell viability in vitro.

British Journal of Pharmacology (2001) 133, 909–919; doi:10.1038/sj.bjp.0704156
Regional localization and developmental profile of acetylcholinesterase‐evoked increases in [3H]‐5‐fluorowillardiine binding to AMPA receptors in rat brain
Authors: Olivera Silvia , Rodriguez‐Ithurralde Daniel , Henley Jeremy M 
Published: January 2005

In addition to its role in hydrolyzing the neurotransmitter acetylcholine, the synaptically enriched enzyme acetylcholinesterase (AChE) has been reported to play an important role in the development and remodelling of neural processes and synapses.
We have shown previously that AChE causes an increase in binding of the specific AMPA receptor ligand (S)‐[3H]‐5‐fluorowillardiine ([3H]‐FW) to rat brain membranes.
In this study we have used quantitative autoradiography to investigate the regional distribution and age‐dependence of AChE‐evoked increases in the binding of [3H]‐FW in rat brain.
Pretreatment of rat brain sections with AChE caused a marked enhancement of [3H]‐FW binding to many, but not all, brain areas. The increased [3H]‐FW binding was blocked by the specific AChE inhibitor BW 284c51.
The maximal potentiation of [3H]‐FW binding occurred at different developmental age‐points in different regions with a profile consistent with the peak periods for synaptogenesis in any given region.
In addition to its effects on brain sections, AChE also strongly potentiated [3H]‐FW binding to detergent solubilized AMPA receptors suggesting a direct action on the receptors themselves rather than an indirect effect on the plasma membrane.
These findings suggest that modulation of AMPA receptors could provide one molecular mechanism for the previously reported effects of AChE on synapse formation, synaptic plasticity and neurodegeneration.

British Journal of Pharmacology (2001) 133, 1055–1062; doi:10.1038/sj.bjp.0704167
A comparison of effects measured with isotonic and isometric recording: II. Concentration‐effect curves for physiological antagonists
Authors: Barlow R B , Bond Susan M , Grant Claire , McQueen D S , Yaqoob Zeenat 
Published: January 2005

If one drug, B, antagonizes another, A, by producing the opposite physiological effect, the antagonist concentration‐effect curves should be affected by the recording system, which limits the range of agonist responses.
With pieces of isolated guinea‐pig ileum taken from adjacent parts of the same animal, one recorded isotonically, the other isometrically with the same load, the isotonic IC50 values for (−)isoprenaline opposing carbachol or histamine were lower than the isometric values (P<0.01) but there was a significant correlation between them (P<0.01): the isotonic curves were steeper (P<0.01) and there were wider shifts in IC50 before increasing the agonist reduced the maximum relaxation.
In similar experiments with pieces of rat uterus in oestrus from the same animal, the concentration‐effect curves for carbachol opposed by increasing concentrations of (−)isoprenaline or (−)adrenaline had slightly lower EC50 values with isometric recording but there was a significant correlation (P<0.01) with isotonic values. The antagonist effect (ratio of the EC50 relative to that for the control) was higher with isotonic recording (P<0.01 for (−)isoprenaline, P<0.025 for (−)adrenaline) and all (27) curves were steeper than the corresponding isometric curve (P<0.001).
The influence of the method of recording on the results is expected from the narrower operational window and smaller upper limit to relaxation with isotonic recording.
A way of obtaining measurements of IC50 against a standard agonist effect is suggested in an Appendix.

British Journal of Pharmacology (2001) 133, 1087–1095; doi:10.1038/sj.bjp.0704169
An alternative pathway for metabolism of leukotriene D4: effects on contractions to cysteinyl‐leukotrienes in the guinea‐pig trachea
Authors: Bäck Magnus , Kumlin Maria , Cotgreave Ian A , Dahlén Sven‐Erik 
Published: January 2005

Contractions of guinea‐pig tracheal preparations to cysteinyl‐leukotrienes (LTC4, LTD4 and LTE4) were characterized in organ baths, and cysteinyl‐leukotriene metabolism was studied using radiolabelled agonists and RP‐HPLC separation.
In the presence of S‐hexyl GSH (100 μM) the metabolism of [3H]‐LTC4 into [3H]‐LTD4 was inhibited and the LTC4‐induced contractions were resistant to CysLT1 receptor antagonism but inhibited by the dual CysLT1/CysLT2 receptor antagonist BAY u9773 (0.3–3 μM) with a pA2‐value of 6.8±0.2.
In the presence of L‐cysteine (5 mM), the metabolism of [3H]‐LTD4 into [3H]‐LTE4 was inhibited and the LTD4‐induced contractions were inhibited by the CysLT1 receptor antagonist ICI 198,615 (1–10 nM) with a pA2‐value of 9.3±0.2. However, at higher concentrations of ICI 198,615 (30–300 nM) a residual contraction to LTD4 was unmasked, and this response was inhibited by BAY u9773 (1–3 μM).
In the presence of the combination of S‐hexyl GSH with L‐cysteine, the LTD4‐induced contractions displayed the characteristics of the LTC4 contractile responses, i.e. resistant to CysLT1 receptor antagonism, increased maximal contractions and slower time‐course. This qualitative change of the LTD4‐induced contraction was also observed in the presence of S‐decyl GSH (100 μM), GSH (10 mM) and GSSG (10 mM).
S‐hexyl GSH, S‐decyl GSH, GSH and GSSG all stimulated a formation of [3H]‐LTC4 from [3H]‐LTD4.
In conclusion, GSH and GSH‐related compounds changed the pharmacology of the LTD4‐induced contractions by stimulating the conversion of LTD4 into LTC4. Moreover, the results indicate that, in addition to the metabolism of LTC4 into LTD4 and LTE4, also the formation of LTC4 from LTD4 may regulate cysteinyl‐leukotriene function.

British Journal of Pharmacology (2001) 133, 1134–1144; doi:10.1038/sj.bjp.0704180