bluuebunny/crossref_metadata_2025_split huggingface dataset:
A2B adenosine receptors mediate relaxation of the pig intravesical ureter: adenosine modulation of non adrenergic non cholinergic excitatory neurotransmission
Authors: Hernández Medardo , Barahona María Victoria , Bustamante Salvador , García‐Sacristán Albino , Orensanz Luis M 
Published: January 2005

The present study was designed to characterize the adenosine receptors involved in the relaxation of the pig intravesical ureter, and to investigate the action of adenosine on the non adrenergic non cholinergic (NANC) excitatory ureteral neurotransmission.
In U46619 (10−7  M)‐contracted strips treated with the adenosine uptake inhibitor, nitrobenzylthioinosine (NBTI, 10−6  M), adenosine and related analogues induced relaxations with the following potency order: 5′‐N‐ethylcarboxamidoadenosine (NECA)=5′‐(N‐cyclopropyl)‐carboxamidoadenosine (CPCA)=2‐chloroadenosine (2‐CA)>adenosine>cyclopentyladenosine (CPA)=N6‐(3‐iodobenzyl)‐adenosine‐5′‐N‐methylcarboxamide (IB‐MECA)=2‐[p‐(carboxyethyl)‐phenylethylamino]‐5′‐N‐ethylcarboxamidoadenosine (CGS21680).
Epithelium removal or incubation with indomethacin (3×10−6  M) and L‐NG‐nitroarginine (L‐NOARG, 3×10−5  M), inhibitors of prostanoids and nitric oxide (NO) synthase, respectively, failed to modify the relaxations to adenosine.
1,3‐dipropyl‐8‐cyclopentylxanthine (DPCPX, 10−8 M) and 4‐(2‐[7‐amino‐2‐(2‐furyl) [1,2,4]‐triazolo[2,3‐a][1,3,5]triazin‐5‐ylamino]ethyl)phenol (ZM 241385, 3×10−8  M and 10−7  M), A1 and A2A receptor selective antagonists, respectively, did not modify the relaxations to adenosine or NECA. 8‐phenyltheophylline (8‐PT, 10−5  M) and DPCPX (10−6  M), which block A1/A2‐receptors, reduced such relaxations.
In strips treated with guanethidine (10−5  M), atropine (10−7  M), L‐NOARG (3×10−5  M) and indomethacin (3×10−6  M), both electrical field stimulation (EFS, 5 Hz) and exogenous ATP (10−4  M) induced contractions of preparations. 8‐PT (10−5  M) increased both contractions. DPCPX (10−8  M), NECA (10−4  M), CPCA, (10−4  M) and 2‐CA (10−4  M) did not alter the contractions to EFS.
The present results suggest that adenosine relaxes the pig intravesical ureter, independently of prostanoids or NO, through activation of A2B‐receptors located in the smooth muscle. This relaxation may modulate the ureteral NANC excitatory neurotransmission through a postsynaptic mechanism.

British Journal of Pharmacology (1999) 126, 969–978; doi:10.1038/sj.bjp.0702386
The inhibition of nicotine‐evoked relaxation of the guinea‐pig isolated basilar artery by some analgesic drugs and progesterone
Authors: Rhodes Keith F , Buckingham Julia C , Kennard Christopher 
Published: January 2005

The purpose of this study was to investigate the mechanism of nicotine‐evoked relaxation of the guinea‐pig isolated basilar artery and to study the effects of drugs associated with the aetiology or treatment of migraine on the nicotine response.
The guinea‐pig isolated basilar artery, pre‐contracted with prostaglandin F2α (PGF2α), in the presence of atropine (3 μM) and guanethidine (3 μM), relaxed on addition of nicotine (0.1 mM) in approximately 50% of preparations. The responses to nicotine were of short duration and blocked in preparations pre‐treated for 10 min with capsaicin (1 μM) and are therefore probably a consequence of the stimulation of trigeminal C fibre terminals.
Responses to nicotine were reduced in the presence of 5‐carboxamidotryptamine, 5‐hydroxytryptamine and sumatriptan in that order of potency. This is consistent with a 5‐HT1 receptor mechanism. These agonists evoked small additional contractions in vessels pre‐contracted with PGF2α.
Indomethacin (0.3–10 μM), aspirin (10–30 μM), and nitro‐L‐arginine methyl ester (L‐NAME, 0.1 mM) reduced nicotine‐evoked relaxation of the basilar artery, suggesting the involvement of both nitric oxide and cyclo‐oxygenase products in this response.
Progesterone (1 μM) markedly reduced the response to nicotine, a possible reflection of the ion channel blocking activity of high concentrations of this compound.
The guinea‐pig basilar artery is a preparation in which the effects of drugs on responses to stimulation of trigeminal nerve terminals can be studied in vitro and may thus be of interest in assessing the actions of drugs used in treatment of headache.

British Journal of Pharmacology (1999) 126, 1003–1008; doi:10.1038/sj.bjp.0702391
Identification of glucoside and carboxyl‐linked glucuronide conjugates of mycophenolic acid in plasma of transplant recipients treated with mycophenolate mofetil
Authors: Shipkova Maria , Armstrong Victor William , Wieland Eberhard , Niedmann Paul Dieter , Schütz Ekkehard , Brenner‐Weiß Gerald , Voihsel Martin , Braun Felix , Oellerich Michael 
Published: January 2005

Mycophenolic acid (MPA), is primarily metabolized in the liver to 7‐O‐MPA‐β‐glucuronide (MPAG). Using RP‐h.p.l.c. we observed three further MPA metabolites, M‐1, M‐2, M‐3, in plasma of transplant recipients on MMF therapy. To obtain information on the structure and source of these metabolites: (A) h.p.l.c. fractions containing either metabolite or MPA were collected and analysed by tandem mass spectrometry; (B) the metabolism of MPA was studied in human liver microsomes in the presence of UDP‐glucuronic acid, UDP‐glucose or NADPH; (C) hydrolysis of metabolites was investigated using β‐glucosidase, β‐glucuronidase or NaOH; (D) cross‐reactivity of each metabolite was tested in an immunoassay for MPA (EMIT).
Mass spectrometry of M‐1, M‐2, MPA and MPAG in the negative ion mode revealed molecular ions of m/z 481, m/z 495, m/z 319 and m/z 495 respectively.
Incubation of microsomes with MPA and UDP‐glucose produced M‐1, with MPA and UDP‐glucuronic acid MPAG and M‐2 were formed, while with MPA and NADPH, M‐3 was observed.
β‐Glucosidase hydrolysed M‐1 completely. β‐Glucuronidase treatment led to a complete disappearance of MPAG whereas the amount of M‐2 was reduced by approximately 30%. Only M‐2 was labile to alkaline treatment.
M‐2 and MPA but not M‐1 and MPAG cross‐reacted in the EMIT assay.
These results suggest that: (i) M‐1 is the 7‐OH glucose conjugate of MPA; (ii) M‐2 is the acyl glucuronide conjugate of MPA; (iii) M‐3 is derived from the hepatic CYP450 system.

British Journal of Pharmacology (1999) 126, 1075–1082; doi:10.1038/sj.bjp.0702399
The putative melatonin receptor antagonist GR128107 is a partial agonist on Xenopus laevis melanophores
Authors: Teh Muy‐Teck , Sugden David 
Published: January 2005

GR128107 (3‐(1‐acetyl‐3‐methyl‐piperidine)‐5‐methoxyindole) has previously been reported to be a competitive melatonin receptor antagonist in blocking melatonin inhibition of [3H]‐dopamine release from rabbit retina, a response mediated by the MT2 receptor subtype.
GR128107, like melatonin, induced a rapid (maximum response in 60–90 min) pigment aggregation in a clonal line of Xenopus laevis melanophores. GR128107 behaved as a partial agonist (pEC50 8.58±0.03, n=3) with an Emax of 0.83 (relative to melatonin, pEC50 10.09±0.03, n=3).
The concentration‐response curve for pigment granule aggregation to both melatonin and GR128107 was displaced in a parallel, rightward manner by melatonin receptor antagonists with very similar potencies; estimated pKB RJ252 (against melatonin 4.60/against GR128107 4.54) <GR135533 (6.40/6.14) < Luzindole (6.45/6.49) < S20929 (6.58/6.65) < 4‐P‐PDOT (6.73/6.85).
Both melatonin‐ and GR128107‐induced pigment granule aggregation was prevented by pre‐treatment of melanophores with pertussis toxin (10–1000 ng ml−1).
Prolonged pre‐treatment of melanophores with melatonin desensitized the pigment aggregation response to GR128107. In desensitized cells, the maximal aggregation produced by GR128107 was only 0.27±0.01 (n=4) and the pEC50 was reduced (vehicle 8.57±0.12; melatonin pre‐treated 7.84±0.09, n=4). The maximal response to melatonin in desensitized melanophores was unchanged but the pEC50 was reduced (vehicle 10.49±0.03; melatonin pre‐treated 9.83±0.04, n=4).
These results demonstrate that GR128107 induces pigment granule aggregation in Xenopus melanophores by activating a cell membrane melatonin receptor coupled via a pertussis toxin‐sensitive G‐protein.
The partial agonist activity of GR128107 in melanophores may be apparent because of the very high density of melatonin receptors in these cells (Bmax 1223 fmol mg protein−1) compared to the low density of sites in rabbit retina (Bmax 3.1 fmol mg protein−1). This suggestion is supported by the finding that GR128107, like melatonin, acted as a full agonist and inhibited forskolin‐stimulation of cyclic AMP accumulation in NIH‐3T3 cells expressing a high density of human mt1 or MT2 receptors.

British Journal of Pharmacology (1999) 126, 1237–1245; doi:10.1038/sj.bjp.0702404
Lung clearance of intratracheally instilled 99mTc‐tobramycin using pulmonary surfactant as vehicle
Authors: Van 't Veen Annemarie , Gommers Diederik , Verbrugge Serge J C , Wollmer Per , Mouton Johan W , Kooij Peter P M , Lachmann Burkhard 
Published: January 2005

The use of pulmonary exogenous surfactant as a vehicle for intratracheally administered antibiotics to improve local antimicrobial therapy has been proposed. The present study investigated lung clearance rates in the rat of intratracheally instilled technetium labelled tobramycin with and without the addition of surfactant to the antibiotic solution.
The influence of surfactant on 99mTc‐tobramycin lung clearance rates was studied dynamically with a gamma‐camera in anaesthetized spontaneously breathing animals and in mechanically ventilated animals.
The results show that instillation of 99mTc‐tobramycin with use of surfactant as vehicle significantly increases 99mTc‐tobramycin lung clearance compared to instillation of 99mTc‐tobramycin solution alone (P=0.006 between the two spontaneously breathing groups of animals and P=0.02 between the two ventilated groups of animals, ANOVA for repeated time measurements). The half life (t½) of composite clearance curves in spontaneous breathing animals was 147 min for animals receiving 99mTc‐tobramycin versus 61 min for animals receiving 99mTc‐tobramycin with surfactant. In mechanically ventilated animals this was 163 min versus 51 min, respectively.
It is concluded that exogenous surfactant, used as vehicle for intratracheally instilled 99mTc‐tobramycin, increases lung clearance rate of 99mTc‐tobramycin in rats.

British Journal of Pharmacology (1999) 126, 1091–1096; doi:10.1038/sj.bjp.0702405
Effect of protein kinase A inhibitors on the production of Aβ40 and Aβ42 by human cells expressing normal and Alzheimer's disease‐linked mutated βAPP and presenilin 1
Authors: Marambaud P , Ancolio K , Alves da Costa C , Checler F 
Published: January 2005

We previously established that the formation of both α‐ and β/γ‐secretase‐derived products generated by human embryonic kidney 293 cells (HEK293) expressing either wild type or mutant βAPP could be stimulated by agonists of the cyclic AMP/protein kinase A pathways. This cyclic AMP‐dependent effect modulates post‐translational events since it is not prevented by actinomycin D or cycloheximide.
We show here that two protein kinase A inhibitors, H89 and PKI, both trigger dose‐dependent inhibition of the basal constitutive production of Aβ40 and Aβ42 by HEK293 cells expressing wild type βAPP751.
H89 also potently inhibits the total Aβ produced by the neocortical neuronal cell line TSM1.
These two inhibitors also drastically reduce the recovery of Aβ40 and Aβ42 produced by HEK293 cells expressing the Swedish (Sw) βAPP and M146V‐presenilin 1 (PS1) mutations responsible for cases of the early‐onset forms of Familial Alzheimer's disease (FAD).
By contrast, H89 and PKI do not significantly affect the recovery of the physiological α‐secretase‐derived fragment APPα.
Our study indicates that protein kinase A inhibitors selectively lower the formation of Aβ40 and Aβ42 in human cells expressing normal and mutant βAPP and PS1 without affecting the physiological α‐secretase pathway in these cells. Selective inhibitors of protein kinase A may be of therapeutic value in both sporadic and Familial Alzheimer's disease, since they may decrease the production of Aβ that is thought to be responsible for the neurodegenerative process.

British Journal of Pharmacology (1999) 126, 1186–1190; doi:10.1038/sj.bjp.0702406
Characterization and tissue location of the neural adenosine receptor in the rat ileum
Authors: Coupar Ian M 
Published: January 2005

The aim of the present investigation was to characterize and determine the tissue location of the adenosine receptors present in the rat ileum using a method that detects drug action on the cholinergic nerves innervating the longitudinal and circular muscles.
The non‐selective adenosine agonist, NECA (10 and 100 nM) caused significant concentration‐related reductions in the circular muscle responses to transmural stimulation over the frequency range of 2.5–40 Hz, but did not affect the responses of the longitudinal muscle, nor did it reduce the muscle responses of the guinea‐pig ileum.
The affinity order of antagonists at inhibiting the effect of NECA on the circular muscle was: CPDPX>8‐PT>DMPX with apparent pA2 values of 9.31, 7.54 and 5.63 respectively. CPDPX (10–100 nM) caused parallel displacements of the concentration‐effect curves to CPA with a pKb value of 9.15 and Schild slope of 1.03.
The agonists previously tested in the rat jejunum peristaltic reflex preparation were also shown to inhibit responses of the rat ileum in the following decreasing order of potency: CPA>NECA>2‐CADO>R‐PIA>S‐PIA>>PAA. In addition, CHA and CCPA were also potent agonists. NECA (100 nM) and CPA (32 nM) did not inhibit carbachol (1 μM)‐induced tone of tissues pre‐treated with TTX (1 μM).
In conclusion, the rat ileum contains inhibitory A1 adenosine receptors situated on cholinergic nerve endings innervating the circular muscle.

British Journal of Pharmacology (1999) 126, 1269–1275; doi:10.1038/sj.bjp.0702411
Inverse agonist abolishes desensitization of a constitutively active mutant of thyrotropin‐releasing hormone receptor: role of cellular calcium and protein kinase C
Authors: Grimberg Hagit , Zaltsman Ilona , Lupu‐Meiri Monica , Gershengorn Marvin C , Oron Yoram 
Published: January 2005

C335Stop is a constitutively active mutant of the TRH receptor (TRH‐R). To investigate the mechanism of the decreased responsiveness of C335Stop TRH‐R, we studied cellular Ca2+ concentrations ([Ca2+]i) in AtT20 cells stably transfected with C335Stop TRH‐R cDNA, or Ca2+‐activated chloride currents in Xenopus laevis oocytes expressing this mutant receptor after injection of cRNA. The competitive TRH‐R binding antagonist, chlorodiazepoxide (CDE), was used as an inverse agonist to study the contribution of constitutive activity to desensitization.
Acute treatment with CDE resulted in a rapid (within minutes) decrease in [Ca2+]i and an increase in the response amplitude to TRH with no measurable change in receptor density. Conversely, removal of chronically administered CDE caused a rapid increase in [Ca2+]i and a decrease in TRH response amplitude.
CDE abolished heterologous desensitization induced by C335Stop TRH‐R on muscarinic m1‐receptor (m1‐R) co‐expressed in Xenopus oocytes.
Chelation of extracellular calcium with EGTA caused a rapid decrease in [Ca2+]i and a concomitant increase in the response to TRH in AtT20 cells expressing C335Stop TRH‐Rs.
Chelerythrine, a specific inhibitor of protein kinase C (PKC), reversed the heterologous desensitization of the response to acetylcholine (ACh). The phosphoserine/phosphothreonine phosphatase inhibitor, okadaic acid, abolished the effect of chelerythrine.
Down‐regulation of PKC by chronic exposure to phorbol 12‐myristate 13‐acetate (PMA) or acute inhibition with chelerythrine caused a partial resensitization of the response to TRH.
Western analysis indicated that the α subtype of protein kinase C was down‐regulated in cells expressing C335Stop TRH‐Rs. Following a 5 min exposure to PMA, the residual αPKC translocated to the particular fraction.
We propose that cells expressing the constitutively active mutant TRH‐R rapidly desensitize their response, utilizing a mechanism mediated by an increase in [Ca2+]i and PKC.

British Journal of Pharmacology (1999) 126, 1097–1106; doi:10.1038/sj.bjp.0702415
Contractile effects by intracellular angiotensin II via receptors with a distinct pharmacological profile in rat aorta
Authors: Brailoiu Eugen , Filipeanu Catalin M , Tica Andrei , Toma Catalin P , De Zeeuw Dick , Nelemans S Adriaan 
Published: January 2005

We studied the effect of intracellular angiotensin II (Ang II) and related peptides on rat aortic contraction, whether this effect is pharmacologically distinguishable from that induced by extracellular stimulation, and determined the Ca2+ source involved.
Compounds were delivered into the cytoplasm of de‐endothelized aorta rings using multilamellar liposomes. Contractions were normalized to the maximum obtained with phenylephrine (10−5 M).
Intracellular administration of Ang II (incorporation range: 0.01–300 nmol mg−1) resulted in a dose‐dependent contraction, insensitive to extracellular administration (10−6 M) of the AT1 receptor antagonist CV11947, the AT2 receptor antagonist PD 123319, or the non‐selective AT receptor antagonist and partial agonist saralasin ([Sar1,Val5,Ala8]‐Ang II (P<0.05).
Intracellular administration of CV11947 or PD 123319 right shifted the dose‐response curve about 1000 fold or 20 fold, respectively. PD 123319 was only effective if less than 30 nmol mg−1 Ang II was incorporated.
Contraction was partially desensitized to a second intracellular Ang II addition after 45 min (P<0.05).
Intracellular administration of Ang I and saralasin also induced contraction (P<0.05). Both responses were sensitive to intracellular CV11947 (P<0.05), but insensitive to PD 123319. The response to Ang I was independent of intracellular captopril.
Contraction induced by extracellular application of Ang II and of Ang I was abolished by extracellular pre‐treatment with saralasin or CV11947 (P<0.05), but not with PD 123319. Extracellular saralasin induced no contraction.
Intracellular Ang II induced contraction was not affected by pre‐treatment with heparin filled liposomes, but completely abolished in Ca2+‐free external medium.
These results support the existence of an intracellular binding site for Ang II in rat aorta. Intracellular stimulation induces contraction dependent on Ca2+‐influx but not on Ins(1,4,5)P3 mediated release from intracellular Ca2+‐stores. Intracellular Ang I and saralasin induce contraction, possibly via the same binding site. Pharmacological properties of this putative intracellular receptor are clearly different from extracellular stimulated AT1 receptors or intracellular angiotensin receptors postulated in other tissue.

British Journal of Pharmacology (1999) 126, 1133–1138; doi:10.1038/sj.bjp.0702421
Down‐regulation of microglial cyclo‐oxygenase‐2 and inducible nitric oxide synthase expression by lipocortin 1
Authors: Minghetti Luisa , Nicolini Alessia , Polazzi Elisabetta , Greco Anita , Perretti Mauro , Parente Luca , Levi Giulio 
Published: January 2005

Activated microglial cells are believed to play an active role in most brain pathologies, during which they can contribute to host defence and repair but also to the establishment of tissue damage. These actions are largely mediated by microglial secretory products, among which are prostaglandins (PGs) and nitric oxide (NO).
The anti‐inflammatory protein, lipocortin 1 (LC1) was reported to have neuroprotective action and to be induced by glucocorticoids in several brain structures, with a preferential expression in microglia. In this paper we tested whether the neuroprotective effect of LC1 could be explained by an inhibitory effect on microglial activation.
We have previously shown that bacterial endotoxin (LPS) strongly stimulates PGE2 and NO production in rat primary microglial cultures, by inducing the expression of the key enzymes cyclo‐oxygenase‐2 (COX‐2) and inducible nitric oxide synthase (iNOS), respectively.
Dexamethasone (DEX, 1–100 nM) and LC1‐derived N‐terminus peptide (peptide Ac2‐26, 1–100 μg ml−1) dose‐dependently inhibited the production of both PGE2 and NO from LPS‐stimulated microglia. The inhibitory effects of DEX on NO and of the peptide on NO and PGE2 synthesis were partially abrogated by a specific antiserum, raised against the N‐terminus of human LC1. The peptide Ac2‐26 did not affect arachidonic acid release from control and LPS‐stimulated microglial cultures.
Western blot experiments showed that the LPS‐induced expression of COX‐2 and iNOS was effectively down‐regulated by DEX (100 nM) and peptide Ac2‐26 (100 μg ml−1).
In conclusion, our findings support the hypothesis that LC1 may foster neuroprotection by limiting microglial activation, through autocrine and paracrine mechanisms.

British Journal of Pharmacology (1999) 126, 1307–1314; doi:10.1038/sj.bjp.0702423
In vitro prostanoid release from spinal cord following peripheral inflammation: effects of substance P, NMDA and capsaicin
Authors: Dirig David M , Yaksh Tony L 
Published: January 2005

Spinal prostanoids are implicated in the development of thermal hyperalgesia after peripheral injury, but the specific prostanoid species that are involved are presently unknown. The current study used an in vitro spinal superfusion model to investigate the effect of substance P (SP), N‐methyl‐d‐aspartate (NMDA), and capsaicin on multiple prostanoid release from dorsal spinal cord of naive rats as well as rats that underwent peripheral injury and inflammation (knee joint kaolin/carrageenan).
In naive rat spinal cords, PGE2 and 6‐keto‐PGF1α, but not TxB2, levels were increased after inclusion of SP, NMDA, or capsaicin in the perfusion medium.
Basal PGE2 levels from spinal cords of animals that underwent 5–72 h of peripheral inflammation were elevated relative to age‐matched naive cohorts. The time course of this increase in basal PGE2 levels coincided with peripheral inflammation, as assessed by knee joint circumference. Basal 6‐keto‐PGF1α levels were not elevated after injury.
From this inflammation‐evoked increase in basal PGE2 levels, SP and capsaicin significantly increased spinal PGE2 release in a dose‐dependent fashion. Capsaicin‐evoked increases were blocked dose‐dependently by inclusion of S(+) ibuprofen in the capsaicin‐containing perfusate.
These data suggest a role for spinal PGE2 and NK‐1 receptor activation in the development of hyperalgesia after injury and demonstrate that this relationship is upregulated in response to peripheral tissue injury and inflammation.

British Journal of Pharmacology (1999) 126, 1333–1340; doi:10.1038/sj.bjp.0702427