bluuebunny/crossref_metadata_2025_split huggingface dataset:
Splice isoforms of α1a‐adrenoceptor in rabbit
Authors: Suzuki Fumiko , Taniguchi Takanobu , Takauji Rumiko , Murata Satoshi , Muramatsu Ikunobu 
Published: January 2005

Two splice isoforms of rabbit α1a‐adrenergic receptor (AR), (named α1a‐OCU.2‐AR and α1a‐OCU.3‐AR) have been isolated from the liver cDNA library in addition to the previously reported isoform (α1a‐OCU.1‐AR). Although they have the identical splice position with human α1a‐AR isoforms, the C‐terminal sequences are distinct from those of human isoforms.
Among these rabbit α1a‐AR isoforms, there are no significant differences in pharmacological properties: high affinity for prazosin, WB4101, KMD‐3213 and YM617 and low affinity for BMY7378, using COS‐7 cells expressing each isoform by radioligand binding assay.
Competitive reverse transcription‐polymerase chain reaction (RT–PCR) analysis revealed that mRNA of α1a‐ARs was expressed in liver, thoracic aorta, brain stem and thalamus of rabbit. The splice isoforms exhibited a distinct distribution pattern in rabbit; α1a‐OCU.1‐AR was expressed most abundantly in those tissues.
CHO clones, stably expressing each isoforms with receptor density 740 fmol mg−1 protein in α1a‐OCU.1‐AR, 1200 fmol mg−1 in α1a‐OCU.2‐AR and 570 fmol mg−1 in α1a‐OCU.3‐AR, respectively, showed a noradrenaline‐induced increase in inositol trisphosphate which was suppressed by prazosin.
Noradrenaline elicited a concentration‐dependent increase in extracellular acidification rate (EAR) in the CHO clones with pEC50 values of 6.19 for α1a‐OCU.1‐AR, 6.49 for α1a‐OCU.2‐AR and 6.58 for α1a‐OCU.3‐AR, respectively.
Noradrenaline caused a concentration‐dependent increase in intracellular Ca2+ concentration ([Ca2+]i) in the CHO clones with pEC50 values of 6.14 for α1a‐OCU.1‐AR, 7.25 for α1a‐OCU.2‐AR and 7.70 for α1a‐OCU.3‐AR, respectively.
In conclusion, the present study shows the occurrence of three splice isoforms of rabbit α1a‐AR, which are unique in C‐terminal sequence and in tissue distribution. They show similar pharmacological profiles in binding studies but α1a‐OCU.3‐AR had the highest potency of noradrenaline in functional studies in spite of the lowest receptor density. These findings suggest that the structure of C‐terminus of α1a‐ARs may give the characteristic functional profile.

British Journal of Pharmacology (2000) 129, 1569–1576; doi:10.1038/sj.bjp.0703242
FP‐receptor mediated trophic effects of prostanoids in rat ventricular cardiomyocytes
Authors: Pönicke K , Giessler C , Grapow M , Heinroth‐Hoffmann I , Becker K , Osten B , Brodde O‐E 
Published: January 2005

The aim of this study was to characterize the receptor subtype involved in cardiac effects of prostanoids. For this purpose we determined in neonatal and adult rat cardiomyocytes effects of prostanoids on inositol phosphate (InsP)‐formation (assessed as accumulation of total [3H]‐InsP's in myo‐[3H]‐inositol pre‐labelled cells) and on rate of protein synthesis (assessed as [3H]‐phenylalanine incorporation), and on contractile force in left ventricular strips of the rat heart. For comparison, effects of prostanoids on InsP‐formation and contractile force were determined in rat thoracic aorta, a classical TP‐receptor containing tissue.
Prostanoid increased InsP‐formation and rate of protein synthesis in neonatal as well as adult rat cardiomyocytes; the order of potency was in neonatal (PGF2α>PGD2PGE2U 46619>PGE1) and adult (PGF2α>PGD2PGE2>U 46619) rat cardiomyocytes well comparable. Moreover, in electrically driven left ventricular strips PGF2α caused positive inotropic effects (pD2 7.5) whereas U 46619 (up to 1 μM) was uneffective.
In contrast, in rat thoracic aorta U 46619 was about 100 times more potent than PGF2α in increasing InsP‐formation and contractile force.
The TP‐receptor antagonist SQ 29548 only weakly antagonized prostanoid‐induced increases in rate of protein synthesis (pKB about 6) in rat cardiomyocytes but was very potent (pKB about 8–9) in antagonizing prostanoid‐induced increases in InsP‐formation and contractile force in rat aorta.
We conclude that, in cardiomyocytes of neonatal and adult rats, the prostanoid‐receptor mediating increases in InsP‐formation and rate of protein synthesis is a FP‐receptor. Moreover, stimulation of these cardiac FP‐receptors can mediate increases in contractile force.

British Journal of Pharmacology (2000) 129, 1723–1731; doi:10.1038/sj.bjp.0703243
O‐1057, a potent water‐soluble cannabinoid receptor agonist with antinociceptive properties
Authors: Pertwee Roger G , Gibson T Michael , Stevenson Lesley A , Ross Ruth A , Banner W Kenneth , Saha Bijali , Razdan Raj K , Martin Billy R 
Published: January 2005

Cannabinoids have low water solubility, necessitating the use of a solubilizing agent. In this paper we investigated whether a novel water‐soluble cannabinoid, 3‐(5′‐cyano‐1′,1′‐dimethylpentyl)‐1‐(4‐N‐morpholinobutyryloxy)‐Δ8‐tetrahydrocannabinol hydrochloride (O‐1057), would interact with cannabinoid receptors when water or saline were used as the only vehicle.
O‐1057 displaced [3H]‐CP55940 from specific binding sites on Chinese hamster ovary (CHO) cell membranes expressing CB1 or CB2 cannabinoid receptors, with pKi values of 8.36 and 7.95 respectively. It also displaced [3H]‐CP55940 from specific binding sites on rat brain membranes (pKi=7.86).
O‐1057 inhibited forskolin‐stimulated cyclic AMP production by both CB1‐ and CB2‐transfected CHO cells (pEC50=9.16 and 9.72 respectively), its potency matching that of CP55940 and exceeding that of Δ9‐tetrahydrocannabinol.
In the mouse isolated vas deferens, O‐1057 inhibited electrically‐evoked contractions with pEC50 and Emax values of 9.73 and 76.84% respectively. It was antagonized by 100 nM SR141716A, the pKB of SR141716A against O‐1057 (8.90) approximating to that against CP55940 (8.97).
O‐1057 also behaved as a CB1 receptor agonist in vivo, reducing mouse spontaneous activity and rectal temperature when injected intravenously and inducing antinociception in the mouse tail flick test when given intravenously (ED50=0.02 mg kg−1), intrathecally, intracerebroventricularly or by gavage. In all these assays, O‐1057 was more potent than Δ9‐tetrahydrocannabinol and, at 0.1 mg kg−1 i.v., was antagonized by SR141716A (3 mg kg−1 i.v.).
These data demonstrate the ability of the water‐soluble cannabinoid, O‐1057, to act as a potent agonist at CB1 and CB2 receptors and warrant investigation of the clinical potential of O‐1057 as an analgesic.

British Journal of Pharmacology (2000) 129, 1577–1584; doi:10.1038/sj.bjp.0703245
Histamine H3‐receptor antagonists inhibit gastroprotection by (R)‐α‐methylhistamine in the rat
Authors: Morini Giuseppina , Grandi Daniela , Stark Holger , Schunack Walter 
Published: January 2005

(R)‐α‐methylhistamine, a selective agonist of histamine H3 receptors, is capable of protecting the gastric mucosa against differently acting damaging agents. The objective of the present study was to determine whether H3 receptors mediate its protective action in the rat.
Gastric mucosal lesions were induced intragastrically (i.g.) by 0.6 N HCl, 1 ml rat−1. (R)‐α‐methylhistamine, 100 mg kg−1 i.g., substantially reduced the severity of macroscopically and histologically assessed damage caused by concentrated acid. Prior treatment with highly selective H3‐receptor antagonists, ciproxifan (0.3, 1 and 3 mg kg−1 i.g.) and clobenpropit (3, 10 and 30 mg kg−1 i.g.), dose‐dependently inhibited the protection exerted by (R)‐α‐methylhistamine up to a complete reversal. When given alone at high doses, both antagonists tended to worsen the HCl‐induced histologic damage.
During basal conditions, (R)‐α‐methylhistamine, 100 mg kg−1 i.g., caused a significant increase in titratable acidity of the gastric juice. Prior treatment with ciproxifan (3 mg kg−1 i.g.) and clobenpropit (30 mg kg−1 i.g.) did not alter the secretory response to (R)‐α‐methylhistamine. Clobenpropit alone, but not ciproxifan, increased the volume of gastric juice, and both compounds alone had no effect on titratable acid.
Present findings support evidence that H3 receptors are actively involved in the maintenance of gastric mucosal integrity, with no apparent role in the regulation of basal gastric acid secretion.

British Journal of Pharmacology (2000) 129, 1597–1600; doi:10.1038/sj.bjp.0703249
Release of dopamine from human neocortex nerve terminals evoked by different stimuli involving extra‐ and intraterminal calcium
Authors: Bonanno Giambattista , Sala Roberta , Cancedda Laura , Cavazzani Paolo , Cossu Massimo , Raiteri Maurizio 
Published: January 2005

The release of [3H]‐dopamine ([3H]‐DA) from human neocortex nerve terminals was studied in synaptosomes prepared from brain specimens removed in neurosurgery and exposed during superfusion to different releasing stimuli.
Treatment with 15 mM KCl, 100 μM 4‐aminopyridine, 1 μM ionomycin or 30 mM caffeine elicited almost identical overflows of tritium. Removal of external Ca2+ ions abolished the overflow evoked by K+ or ionomycin and largely prevented that caused by 4‐aminopyridine; the overflow evoked by caffeine was completely independent of external Ca2+.
Exposure of synaptosomes to 25 μM of the broad spectrum calcium channel blocker CdCl2 strongly inhibited the 4‐aminopyridine‐induced tritium overflow while that evoked by ionomycin remained unaffected.
The Ca2+ chelator, 1,2‐bis‐(2‐aminophenoxy)ethane‐N,N,N′,N′ tetraacetic acid (BAPTA), reduced significantly the K+‐ and the caffeine‐induced tritium overflow. The effect of caffeine was attenuated by exposure to the ryanodine receptor blocker dantrolene or when the membrane‐impermeant inositol trisphosphate receptor antagonist, heparin, was entrapped into synaptosomes; the combined treatment with dantrolene and heparin abolished the release elicited by caffeine.
Tetanus toxin, entrapped into human neocortex synaptosomes to avoid prolonged incubation, inhibited in a concentration‐dependent manner the K+‐ or the 4‐aminopyridine‐evoked tritium overflow; in contrast, the release stimulated by ionomycin and by caffeine were both totally insensitive to the same concentrations of tetanus toxin. Western blot analysis showed about 50% reduction of the content of the vesicular protein, synaptobrevin, in synaptosomes poisoned with tetanus toxin.
In conclusion, the release of dopamine from human neocortex nerve terminals can be triggered by Ca2+ ions originating from various sources. It seems that stimuli not leading to activation of voltage‐sensitive Ca2+ channels elicit Ca2+‐dependent, probably exocytotic, release that is insensitive to tetanus toxin.

British Journal of Pharmacology (2000) 129, 1780–1786; doi:10.1038/sj.bjp.0703251
Pharmacokinetic‐pharmacodynamic modelling of the convulsant interaction between norfloxacin and biphenyl acetic acid in rats
Authors: Marchand Sandrine , Pariat Claudine , Bouquet Serge , Courtois Philippe , Couet William 
Published: January 2005

Fluoroquinolones (FQs) are associated with a low incidence of central nervous system (CNS) side effects, possibly leading to convulsions, especially when co‐administered with nonsteroidal anti‐inflammatory drugs (NSAIDS). Although the in vivo pro‐convulsant activity of NSAIDS is essentially unknown, the convulsant potential of FQs is traditionally evaluated by in vitro γ‐aminobutyric acid (GABA) binding experiments in the presence of 4‐biphenyl acetic acid (BPAA), the active metabolite of fenbufen.
The aim of this study was therefore to investigate the BPAA‐norfloxacin convulsant interaction in vivo.
Male Sprague‐Dawley rats (n=27) were given BPAA orally, at various doses 1 h before norfloxacin infusion, which was maintained until the onset of maximal seizures, when cerebrospinal fluid (CSF) and plasma samples were collected for analysis.
An inhibitory Emax effect model with a baseline effect parameter was fitted to the norfloxacin versus BPAA concentrations in the CSF, previously shown to be part of the biophase. This model includes three parameters: the concentrations of norfloxacin in the absence of BPAA (CCSF0, Nor), and when BPAA concentration tends toward infinity (CCSFbase, Nor), and the BPAA concentration for which half of the maximal effect is observed (CCSF50, BPAA). The maximal proconvulsant effect of BPAA is given by the CCSF0, Nor / CCSFbase, Nor ratio, estimated to approximately 6 in this study.
Derived models were developed in plasma to account for the non‐linear CSF diffusion of norfloxacin and protein binding of BPAA.
In conclusion this study has shown that the convulsant interaction between norfloxacin and BPAA in rats, can be adequately characterized by modelling of the CSF concentrations of the two drugs at the onset of activity, following their administration in various proportions.

British Journal of Pharmacology (2000) 129, 1609–1616; doi:10.1038/sj.bjp.0703260
Investigations into pharmacological antagonism of general anaesthesia
Authors: Little H J , Clark A , Watson W P 
Published: January 2005

The effects of convulsant drugs, and of thyrotropin releasing hormone (TRH), were examined on the general anaesthetic actions of ketamine, ethanol, pentobarbitone and propofol in mice. The aim was to investigate the possibility of selective antagonism, which, if seen, would provide information about the mechanism of the anaesthesia.
The general anaesthetic effects of ketamine were unaffected by bicuculline; antagonism was seen with 4‐aminopyridine and significant potentiation with 300 mg kg−1 NMDLA (N‐methyl‐DL‐aspartate). The calcium agonist, Bay K 8644, potentiated the anaesthesia produced by ketamine and antagonism of such anaesthesia was seen with TRH.
A small, but significant, antagonism of the general anaesthesia produced by ethanol was seen with bicuculline, and a small, significant, potentiation with 4‐aminopyridine. There was an antagonist effect of TRH, but no effect of NMDLA.
Potentiation of the anaesthetic effects of pentobarbitone was seen with NMDLA and with 4‐aminopyridine and the lower dose of bicuculline (2.7 mg kg−1) also caused potentiation. There was no significant change in the ED50 value for pentobarbitone anaesthesia with TRH.
Bicuculline did not alter the anaesthetic actions of propofol, while potentiation was seen with NMDLA and 4‐aminopyridine. TRH had no significant effect on propofol anaesthetic, but Bay K 8644 at 1 mg kg−1 significantly potentiated the anaesthesia.
These results suggest that potentiation of GABAA transmission or inhibition of NMDA receptor‐mediated transmission do not appear to play a major role in the production of general anaesthesia by the agents used.

British Journal of Pharmacology (2000) 129, 1755–1763; doi:10.1038/sj.bjp.0703262
Antagonism of nicotinic receptors of rat chromaffin cells by N,N,N‐trimethyl‐1‐(4‐trans‐stilbenoxy)‐2‐propylammonium iodide: a patch clamp and ligand binding study
Authors: Di Angelantonio Silvia , Nistri Andrea , Moretti Milena , Clementi Francesco , Gotti Cecilia 
Published: January 2005

The effect of the oxystilbene derivative F3 was tested on nAChRs of whole‐cell patch‐clamped rat chromaffin cells in vitro and of rat adrenal gland membranes using 125I‐epibatidine.
F3 (30 nM) rapidly and reversibly blocked inward currents generated by pulse applications of nicotine, shifting the dose‐response curve to the right in a parallel fashion without changing the maximum response. The action of F3 was voltage insensitive and not due to altered current reversal potential.
The R isomer of F3 was more potent (IC50=350±30 nM) than its S‐enantiomer (IC50=1.5±0.3 μM). Nicotine‐evoked currents were insensitive to 10 μM α‐bungarotoxin.
Equi‐amplitude currents evoked by nicotine or epibatidine were similarly antagonized by R‐F3 in a reversible fashion. Epibatidine‐evoked currents readily produced receptor desensitization.
Adrenal membranes specifically bound 125I‐epibatidine with a single population of binding sites endowed with high affinity (KD=159 pM) and Bmax of 6.5±1.3 fmol mg−1 of protein.
125I‐epibatidine binding was specifically displaced by cytisine (Ki=68 nM) or ACh (Ki=348 nM). F3 specifically displaced 125I‐epibatidine binding although with lower affinity (Ki=29.6 μM) than in electrophysiological experiments. 125I‐epibatidine binding to rat adrenal tissue was insensitive to α‐bungarotoxin which readily antagonized 125I‐epibatidine binding to bovine adrenal tissue.
The present results suggest that F3 is a relatively potent and apparently competitive antagonist of nAChRs on rat chromaffin cells. Since previous studies have indicated that F3 targets different subtypes on chick neuronal tissue, it appears that nAChRs display interspecies differences to be considered for drug development studies.

British Journal of Pharmacology (2000) 129, 1771–1779; doi:10.1038/sj.bjp.0703264
Impaired vascular sensitivity to nitric oxide in the coronary microvasculature after endotoxaemia
Authors: Bogle Richard G , McLean Peter G , Ahluwalia Amrita , Vallance Patrick 
Published: January 2005

The effects of endotoxaemia on coronary vasodilator responses to bradykinin (BK), sodium nitroprusside (SNP) and nicardipine were investigated in the rat isolated heart perfused at constant flow ex vivo.
Dose‐dependent reductions in coronary perfusion pressure reaching a maximum of 56±3 and 57±5 mmHg were observed for BK and SNP respectively. The BK response was biphasic, consisting of a rapid dilator response that was insensitive to NGnitro‐L‐arginine methyl ester (L‐NAME, 0.1 mM) and a second slower component whose duration was attenuated by L‐NAME.
Hearts obtained from rats treated with endotoxin (2.5 mg kg−1, i.p.) for 2 or 6 h had increased basal coronary perfusion pressure and reduced vasodilator responses to BK or SNP. Dilator responses to nicardipine were not affected by endotoxin treatment. In vitro perfusion of hearts from endotoxin‐treated rats with L‐NAME (0.1 mM) restored SNP responses to control values.
Treatment with dexamethasone (1 mg kg−1), 1 h before endotoxin did not alter the endotoxin‐induced impairment of dilator responses to BK or SNP.
These results show that coronary microvascular responses are altered following endotoxin exposure. Endotoxin results in increased coronary microvascular tone despite induction of NO synthase and inhibits the dilator response to BK and SNP, vasodilators that act via the release of NO. Responses to SNP in endotoxin‐treated hearts were restored to control values in the presence of L‐NAME suggesting that enhanced endogenous NO synthesis might saturate guanylate cyclase resulting in reduced response to NO donors. The reduced response to vasodilators and increased coronary resistance might be important in determining the response of the coronary circulation to systemic inflammation and infection.

British Journal of Pharmacology (2000) 130, 118–124; doi:10.1038/sj.bjp.0703267
Proteinase‐activated receptor‐2 (PAR‐2): regulation of salivary and pancreatic exocrine secretion in vivo in rats and mice
Authors: Kawabata Atsufumi , Nishikawa Hiroyuki , Kuroda Ryotaro , Kawai Kenzo , Hollenberg Morley D 
Published: January 2005

Proteinase‐activated receptor‐2 (PAR‐2) is expressed throughout the gastrointestinal tract including the pancreas, and may be involved in digestive functions. The aim of our study was to evaluate a potential role for PAR‐2 in regulating salivary and pancreatic exocrine secretion in vivo.
PAR‐2‐activating peptides (PAR‐2‐APs), but not selective PAR‐1‐APs, administered intravenously, increased salivary secretion in the mouse or rat; this effect of the PAR‐2‐APs was unaffected by atropine, phentolamine, propranolol or indomethacin.
Secretion (amylase) by rat parotid gland slices in vitro was also stimulated by PAR‐2‐APs and trypsin, but not by activation of other PARs.
PAR‐2‐APs, administered to rats in vivo, caused a prompt effect on pancreatic exocrine secretion.
PAR‐2 mRNA, known to be present in pancreatic tissue, was also detected in parotid tissue.
Our results indicate that in addition to a potential role in regulating cardiovascular and respiratory functions, PAR‐2 may also play a general role in vivo for the direct regulation of glandular exocrine secretion.

British Journal of Pharmacology (2000) 129, 1808–1814; doi:10.1038/sj.bjp.0703274
Evaluation of iNOS‐dependent and independent mechanisms of the microvascular permeability change induced by lipopolysaccharide
Authors: Fujii Emiko , Yoshioka Toshimasa , Ishida Hiroyasu , Irie Kaoru , Muraki Takamura 
Published: January 2005

Subcutaneous injection of lipopolysaccharide (LPS) increases plasma leakage in mouse skin. Pretreatment with LPS conditions mice tolerant to the LPS‐induced plasma leakage. Nitric oxide (NO) has been suggested to be involved in these LPS effects. A specific role of inducible NO synthase (iNOS) was investigated in the LPS‐induced plasma leakage using iNOS deficient mice.
Plasma leakage in mouse skin was measured by the local accumulation of Pontamine sky blue at the site of subcutaneous injection of LPS (Sal. typhimurium). LPS (100–400 μg site−1) produced a dose‐related increase in dye leakage in both iNOS deficient and wild‐type mice with about 40% less dye leakage in iNOS deficient mice.
Indomethacin (5 mg kg−1), N‐[‐2‐cyclohexyloxy]‐4‐nitrophenyl methanesulphonamide (NS‐398) (1 mg kg−1), diphenhydramine (10 mg kg−1) and anti‐TNF‐α antibody (dilution 1 : 400, 10 ml kg−1) inhibited the LPS‐induced dye leakage in both iNOS deficient and wild‐type mice, whereas NG‐nitro‐L‐arginine methyl ester (L‐NAME) (10 mg kg−1) or aminoguanidine (10 mg kg−1) inhibited that in wild‐type but not in iNOS deficient mice.
Pretreatment with LPS (0.15 mg kg−1 i.p.) 4 h before decreased the LPS‐induced dye leakage in wild‐type but not in iNOS deficient mice. LPS pretreatment increased serum corticosterone levels in both mice, while it increased the serum nitrate/nitrite levels in wild‐type but not in iNOS deficient mice.
These studies indicate that an increase in vascular permeability induced by LPS is mediated by NO produced by iNOS, eicosanoids, histamine and TNF‐α. The tolerance against LPS‐induced vascular permeability change may be mediated by iNOS induction but not by an increased release of endogenous corticosteroids.

British Journal of Pharmacology (2000) 130, 90–94; doi:10.1038/sj.bjp.0703277
Evidence for the involvement of peroxynitrite in ischaemic preconditioning in rat isolated hearts
Authors: Altuǧ Sedat , Demiryürek A Tuncay , Kane Kathleen A , Kanzik İlker 
Published: January 2005

The aim of this study was to investigate the involvement of peroxynitrite, reactive metabolite originating from nitric oxide and superoxide, in preconditioning of the ischaemic myocardium in rat isolated hearts.
Isolated hearts perfused with Krebs‐Henseleit solution were preconditioned either by 3 min of coronary artery occlusion (CAO) or by peroxynitrite administration at three different concentrations (0.1, 1, 10 μM) for 3 min, followed by 10 min reperfusion and 30 min of CAO. Peroxynitrite, at 1 μM concentration, decreased the incidence of VT from 100% (n=14) to 62% (n=13) and abolished the occurrence of VF (50% in the control group).
N‐2‐mercaptopropionylglycine (MPG, 1 μM–10 mM) produced a concentration‐dependent inhibition of peroxynitrite signals in luminol chemiluminescence and 67±1% inhibition was observed at 100 μM (n=7). MPG (at 300 μM, n=7) added to the perfusate 10 min prior to ischaemic preconditioning or peroxynitrite infusion and maintained until CAO, significantly reversed the beneficial effects of the ischaemic and peroxynitrite‐treated groups. MPG administration in the peroxynitrite‐treated group increased the incidence of VT from 62% (n=13) to 100% (n=10) and total VF from 0% (n=0) to 67% (n=10). Similarly, MPG elevated the incidence of VT from 50% (n=10) to 100% (n=8) in the ischaemic preconditioned group. On its own, MPG did not affect the severity of cardiac arrhythmias.
These results suggest that endogenously produced peroxynitrite plays a significant role in the antiarrhythmic effect of ischaemic preconditioning in the rat isolated hearts.

British Journal of Pharmacology (2000) 130, 125–131; doi:10.1038/sj.bjp.0703280