bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evidence that rat hepatocytes co‐express functional P2Y1and P2Y2receptors
Authors: Dixon C Jane , Woods Niall M , Webb Tania E , Green Anne K 
Published: January 2005

Previous studies have indicated the expression of multiple P2Y receptors by rat hepatocytes although they have not been identified. Here we show by reverse transcriptase‐polymerase chain reaction (RT–PCR) that rat hepatocytes express mRNA encoding all of the four cloned rat P2Y receptors (P2Y1, P2Y2, P2Y4and P2Y6).The effects of UTP have been examined on single aequorin‐injected rat hepatocytes. The [Ca2+]itransients induced by UTP were indistinguishable from those induced by ATP in the same cell. The modulatory effects of elevated intracellular cyclic AMP concentration were the same on both UTP‐ and ATP‐induced [Ca2+]itransients.UDP, an agonist at the P2Y6receptor, failed to induce transients in hepatocytes, indicating that functional P2Y6receptors coupled to increased [Ca2+]iare not expressed.The transients evoked by ADP were more sensitive to inhibition by suramin than those induced by either ATP or UTP. Within an individual cell, the transients induced by ATP and UTP were inhibited by the same concentration of suramin. This sensitivity of ATP and UTP responses to suramin suggests action through P2Y2rather than P2Y4receptors.Co‐application of 30 μMpyridoxalphosphate‐6‐azophenyl‐2′,4′‐disulphonic acid (PPADS) caused a decrease in frequency and amplitude of transients induced by ADP. ATP‐ and UTP‐induced transients also displayed a decrease in amplitude in response to addition of PPADS, but this was accompanied by an increase in frequency of transients.In conclusion the data presented here are consistent with the co‐expression of P2Y1and P2Y2receptors by rat hepatocytes.British Journal of Pharmacology(2000)129, 764–770; doi:10.1038/sj.bjp.0703103
The group II metabotropic glutamate receptor agonist, DCG‐IV, alleviates akinesia following intranigral or intraventricular administration in the reserpine‐treated rat
Authors: Dawson Lee , Chadha Anita , Megalou Maria , Duty Susan 
Published: January 2005

This study examined whether activation of group II metabotropic glutamate (mGlu) receptors in the substantia nigra pars reticulata (SNr) could reverse akinesia in a rodent model of Parkinson's disease (PD).
Male Sprague Dawley rats, stereotaxically cannulated above either the SNr or third ventricle, were rendered akinetic by injection of reserpine (5 mg kg−1 s.c.). Eighteen hours later, the rotational behaviour induced by unilateral injection of the group II mGlu receptor agonist, (2S,2′R,3′R)‐2‐(2′,3′‐dicarboxycyclopropyl)glycine (DCG‐IV), was examined.
Following intranigral injection, DCG‐IV (0.125–0.75 nmol in 0.1 μl) produced a dose‐dependent increase in net contraversive rotations (n=6–8 animals per dose), reaching a maximum of 395±51 rotations 60 min−1 after 0.75 nmol. The effects of DCG‐IV (0.5 nmol) were inhibited by 63.0±9.0% following 30 min pre‐treatment with the group II mGlu receptor antagonist, (2S)‐α‐ethylglutamic acid (EGLU; 100 nmol in 0.2 μl; n=6).
Following intraventricular injection, DCG‐IV (0.125–1.5 nmol in 2 μl) produced a dose‐dependent increase in bilateral locomotor activity (n=6–7 animals per dose), reaching a maximum of 180±21 locomotor units 30 min−1 after 0.5 nmol. Pre‐treatment with EGLU (200 nmol in 2 μl) inhibited the effects of DCG‐IV (0.5 nmol) by 68.2±12.3% (n=5).
These data show that activation of group II mGlu receptors in the SNr provides relief of akinesia in the reserpinized rat model of PD. The reversal seen following intraventricular administration supports the likely therapeutic benefit of systemically‐active group II mGlu receptor agonists in PD.

British Journal of Pharmacology (2000) 129, 541–546; doi:10.1038/sj.bjp.0703105
Pharmacological profile of BIBN4096BS, the first selective small molecule CGRP antagonist
Authors: Doods Henri , Hallermayer Gerhard , Wu Dongmei , Entzeroth Michael , Rudolf Klaus , Engel Wolfhard , Eberlein Wolfgang 
Published: January 2005

Calcitonin gene‐related peptide (CGRP) is one of the most potent endogenous vasodilators known. This peptide is increased during migraine attacks and has been implicated in the pathogenesis of migraine headache. Here we report on the first small molecule selective CGRP antagonist: BIBN4096BS. In vitro, this compound is extremely potent at primate CGRP receptors exhibiting an affinity (Ki) for human CGRP receptors of 14.4±6.3 (n=4) pM. In an in vivo model, BIBN4096BS in doses between 1 and 30 μg kg−1 (i.v.) inhibited the effects of CGRP, released by stimulation of the trigeminal ganglion, on facial blood flow in marmoset monkeys. It is concluded that BIBN4096BS is a potent and selective CGRP antagonist.British Journal of Pharmacology (2000) 129, 420–423; doi:10.1038/sj.bjp.0703110
The pharmacology of hSK1 Ca2+‐activated K+ channels expressed in mammalian cell lines
Authors: Shah M , Haylett D G 
Published: January 2005

The pharmacology of hSK1, a small conductance calcium‐activated potassium channel, was studied in mammalian cell lines (HEK293 and COS‐7). In these cell types, hSK1 forms an apamin‐sensitive channel with an IC50 for apamin of 8 nM in HEK293 cells and 12 nM in COS‐7 cells. The currents in HEK293 cells were also sensitive to tubocurarine (IC50=23 μM), dequalinium (IC50=0.4 μM), and the novel dequalinium analogue, UCL1848 (IC50=1 nM). These results are very different from the pharmacology of hSK1 channels expressed in Xenopus oocytes and suggest the properties of the channel may depend on the expression system. Our findings also raise questions about the role of SK1 channels in generating the apamin‐insensitive slow afterhyperpolarization observed in central neurones.British Journal of Pharmacology (2000) 129, 627–630; doi:10.1038/sj.bjp.0703111
Voltage‐dependent inhibition of the muscarinic cationic current in guinea‐pig ileal cells by SK&F 96365
Authors: Zholos A V , Tsytsyura Ya D , Philyppov I B , Shuba M F , Bolton T B 
Published: January 2005

The effects of SK&F 96365 on cationic current evoked either by activating muscarinic receptors with carbachol or by intracellularly applied GTPγS (in the absence of carbachol) were studied using patch‐clamp recording techniques in single guinea‐pig ileal smooth muscle cells.
SK&F 96365 reversibly inhibited the muscarinic receptor cationic current in a concentration‐, time‐ and voltage‐dependent manner producing concomitant alteration of the steady‐state I‐V relationship shape which could be explained by assuming that increasing membrane positivity increased the affinity of the blocker. The inhibition was similar for both carbachol‐ and GTPγS‐evoked currents suggesting that the cationic channel rather than the muscarinic receptor was the primary site of the SK&F 96365 action.
Increased membrane positivity induced additional rapid inhibition of the cationic current by SK&F 96365 which was more slowly relieved during membrane repolarization. Both the inhibition and disinhibition time course could be well fitted by a single exponential function with the time constants decreasing with increasing positivity for the inhibition (e‐fold per about 12 mV) and approximately linearly decreasing with increasing negativity for the disinhibition.
At a constant SK&F 96365 concentration, the degree of cationic current inhibition was a sigmoidal function of the membrane potential with a potential of half‐maximal increase positive to about +30 mV and a slope factor of about −13 mV.
Increasing the duration of voltage steps at −80 or at 80 mV, increased the percentage inhibition; the degree of inhibition was almost identical at both potentials providing evidence that the same cationic channel was responsible for the cationic current both at negative and at positive potentials.
It is concluded that the distinctive and unique mode of SK&F 96365 action on the muscarinic receptor cationic channel is a valuable tool in future molecular biology studies of this channel.

British Journal of Pharmacology (2000) 129, 695–702; doi:10.1038/sj.bjp.0703115
Bromoenol lactone enhances the permeabilization of rat submandibular acinar cells by P2X7 agonists
Authors: Chaïb N , Kabré E , Alzola E , Pochet S , Dehaye J P 
Published: January 2005

The permeabilizing effect of P2X7 agonists was tested in rat submandibular acinar cells using the uptake of ethidium bromide as an index.
The uptake of ethidium bromide by acini incubated at 37°C in the presence of 1 mM ATP increased with time and reached after 5 min about 10% of maximal uptake measured in the presence of digitonin.
The response to ATP was dose‐dependent (half‐maximal concentration around 40 μM) and it was decreased when the temperature was lowered to 25°C.
Benzoyl‐ATP reproduced the response to ATP (half‐maximal concentration around 10 μM). UTP or 2‐methylthioATP had no effect.
The permeabilization in response to ATP was blocked by oxidized ATP and by magnesium and inhibited by Coomassie blue.
ATP increased the activity of a calcium‐insensitive phospholipase A2 (iPLA2).
Bromoenol lactone (BEL) inhibited the iPLA2 stimulated by ATP but potentiated the uptake of ethidium bromide in response to the purinergic agonist.
From these results it is concluded that the activation of P2X7 receptors permeabilizes rat submandibular acinar cells. The pore‐forming activity of the receptor might be negatively regulated by the concomitant activation of the iPLA2 by the receptor.

British Journal of Pharmacology (2000) 129, 703–708; doi:10.1038/sj.bjp.0703124
Harmane produces hypotension following microinjection into the RVLM: possible role of I1‐imidazoline receptors
Authors: Musgrave I F , Badoer E 
Published: January 2005

The β‐carboline, harmane (0.1–1.0 nmol) produces dose dependent hypotension when microinjected unilaterally into the rostral ventrolateral medulla (RVLM) of the anaesthetized rat. The potency of harmane on blood pressure is similar to that of the imidazoline, clonidine. The hypotensive effects of both clonidine and harmane are reversed by microinjection of the relatively I1‐receptor selective antagonist efaroxan (20 nmol). These results are consistent with harmane acting at an I1‐receptor in the RVLM. This is the first report of an endogenous ligand for I1‐receptors that has central effects on blood pressure.British Journal of Pharmacology (2000) 129, 1057–1059; doi:10.1038/sj.bjp.0703142
Potassium‐ and acetylcholine‐induced vasorelaxation in mice lacking endothelial nitric oxide synthase
Authors: Ding Hong , Kubes Paul , Triggle Chris 
Published: January 2005

The contribution of an endothelium‐derived hyperpolarizing factor (EDHF) was investigated in saphenous and mesenteric arteries from endothelial nitric oxide synthase (eNOS) (−/−) and (+/+) mice.
Acetylcholine‐induced endothelium‐dependent relaxation of saphenous arteries of eNOS(−/−) was resistant to Nω‐nitro‐L‐arginine (L‐NNA) and indomethacin, as well as the guanylyl cyclase inhibitor, 1H‐(1,2,4)oxadiazolo(4,3‐a) quinoxalin‐1‐one(ODQ).
Potassium (K+) induced a dose‐dependent vasorelaxation which was endothelium‐independent and unaffected by either L‐NNA or indomethacin in both saphenous and mesenteric arteries from eNOS(−/−) or (+/+) mice.
Thirty μM barium (Ba2+) and 10 μM ouabain partially blocked potassium‐induced, but had no effect on acetylcholine‐induced vasorelaxation in saphenous arteries.
Acetylcholine‐induced relaxation was blocked by a combination of charybdotoxin (ChTX) and apamin which had no effect on K+‐induced relaxation, however, iberiotoxin (IbTX) was ineffective against either acetylcholine‐ or K+‐induced relaxation.
Thirty μM Ba2+ partially blocked both K+‐ and acetylcholine‐induced relaxation of mesenteric arteries, and K+, but not acetylcholine‐induced relaxation was totally blocked by the combination of Ba2+ and ouabain.
These data indicate that acetylcholine‐induced relaxation cannot be mimicked by elevating extracellular K+ in saphenous arteries from either eNOS(−/−) or (+/+) mice, but K+ may contribute to EDHF‐mediated relaxation of mesenteric arteries.

British Journal of Pharmacology (2000) 129, 1194–1200; doi:10.1038/sj.bjp.0703144
Heterogeneous mechanisms of endothelium‐dependent relaxation for thrombin and peptide activators of protease‐activated receptor‐1 in porcine isolated coronary artery
Authors: Hamilton Justin R , Cocks Thomas M 
Published: January 2005

Mechanisms of protease‐activated receptor‐1 (PAR1)‐ and PAR2‐induced relaxation were investigated in pre‐contracted porcine coronary artery ring preparations.
Thrombin (0.01–0.3 u ml−1) and the PAR1‐activating peptide SFLLRN (0.1–10 μM) caused concentration‐ and endothelium‐dependent relaxation. pEC50s (−log u ml−1 for enzymes, −log M for peptides) and maximum relaxations (Rmax, %) for thrombin were 1.8±0.1 and 93.5±2.8% respectively, and for SFLLRN 6.8±0.1 and 90.8±1.3%. Similar concentration‐ and endothelium‐dependent relaxations occurred with trypsin (pEC50 2.3±0.2; Rmax 94.1±1.9%) and the PAR2‐activating peptide SLIGRL (pEC50 6.5±0.2; Rmax 92.4±1.6%).
Relaxations to thrombin, SFLLRN, trypsin and SLIGRL were significantly inhibited (P<0.05) to similar extents by the nitric oxide (NO) synthase inhibitor NG‐nitro‐L‐arginine (L‐NOARG; 100 μM) and the NO scavenger oxyhaemoglobin (20 μM), both separately and in combination.
In the presence of the L‐type voltage‐operated calcium channel (L‐VOCC) inhibitor nifedipine (0.3 μM), K+ (67 mM) abolished the L‐NOARG‐resistant relaxations to thrombin, SFLLRN, trypsin and SLIGRL. However, nifedipine alone significantly (P<0.05) reduced the pEC50 (1.5±0.1) and Rmax (77.5±7.0%) for thrombin but had no effect on relaxations to SFLLRN, trypsin or SLIGRL. Furthermore, L‐NOARG‐resistant relaxations to thrombin were abolished by nifedipine, whereas relaxations to SFLLRN, trypsin or SLIGRL were not further inhibited by combined treatment with nifedipine and L‐NOARG, than they were with L‐NOARG treatment alone.
Similar selective inhibition of the L‐NOARG‐resistant relaxation to thrombin, but not SFLLRN, occurred with verapamil (1 μM) and diltiazem (3 μM).
Our results suggest heterogeneous mechanisms in the NO‐independent relaxation to thrombin and peptide activators of PAR1 in the porcine coronary artery.

British Journal of Pharmacology (2000) 130, 181–188; doi:10.1038/sj.bjp.0703146
The effect of long‐term streptozotocin‐induced diabetes on contractile and relaxation responses of coronary arteries: selective attenuation of CGRP‐induced relaxations
Authors: Sheykhzade Majid , Dalsgaard Grethe T , Johansen Tue , Nyborg Niels C Berg 
Published: January 2005

This study investigates the effect of partially metabolic controlled long‐term (34 weeks) streptozotocin (STZ)‐induced diabetes on relaxation and contractile responses of isolated coronary arteries to seven different vasoactive agents.
The average fasting and non‐fasting blood glucose concentrations (mM) were significantly elevated in STZ‐induced diabetic rats (P<0.0001; 10.4±0.4 and 16.6±1.1, n=15) compared to those (4.3±0.03 and 4.7±0.18, n=11) in age‐matched controls. The level of glycated haemoglobin (HbA1) was also significantly (P<0.0001) increased in STZ‐induced diabetic rats. In STZ‐induced diabetic rats, the HbA1 levels were significantly correlated with the non‐fasting blood glucose concentrations (r=0.76; P=0.003; n=13). In both groups, there was no significant correlation between the HbA1 levels and maximal responses or sensitivities to the vasoactive agents.
The maximal relaxation induced by rat‐αcalcitonin gene‐related peptide (rat‐αCGRP) was significantly attenuated in the coronary arteries of STZ‐induced diabetic rats (P<0.05; 40±7%, n=15) compared to that in age‐matched controls (63±3%, n=11). However, there was no significant difference in the sensitivity to rat‐αCGRP between the two groups.
There was no significant difference in either maximal response or sensitivity to any of the six other vasoactive agents between STZ‐ induced diabetic rats (n=15) and age‐matched controls (n=11).
Our results show that partially metabolic controlled long‐term (34 weeks) STZ‐induced diabetes causes a selective depression of rat‐αCGRP‐induced relaxation in the intramural coronary arteries of Wistar rats.

British Journal of Pharmacology (2000) 129, 1212–1218; doi:10.1038/sj.bjp.0703159
BIIE0246, a potent and highly selective non‐peptide neuropeptide Y Y2 receptor antagonist
Authors: Dumont Yvan , Cadieux Alain , Doods Henri , Pheng Leng Hong , Abounader Roger , Hamel Edith , Jacques Danielle , Regoli Domenico , Quirion Rémi 
Published: January 2005

BIIE0246, a newly synthesized non‐peptide neuropeptide Y (NPY) Y2 receptor antagonist, was able to compete with high affinity (8 to 15 nM) for specific [125I]PYY3–36 binding sites in HEK293 cells transfected with the rat Y2 receptor cDNA, and in rat brain and human frontal cortex membrane homogenates.
Interestingly, in rat brain homogenates while NPY, C2‐NPY and PYY3–36 inhibited all specific [125I]PYY3–36 labelling, BIIE0246 failed to compete for all specific binding suggesting that [125I]PYY3–36 recognized, in addition to the Y2 subtype, another population of specific NPY binding sites, most likely the Y5 receptor.
Quantitative receptor autoradiographic data confirmed the presence of [125I]PYY3–36/BIIE0246‐sensitive (Y2) and‐insensitive (Y5) binding sites in the rat brain as well as in the marmoset monkey and human hippocampal formation.
In the rat vas deferens and dog saphenous vein (two prototypical Y2 bioassays), BIIE0246 induced parallel shifts to the right of NPY concentration‐response curves with pA2 values of 8.1 and 8.6, respectively. In the rat colon (a Y2/Y4 bioassay), BIIE0246 (1 μM) completely blocked the contraction induced by PYY3–36, but not that of [Leu31,Pro34]NPY (a Y1, Y4 and Y5 agonist) and hPP (a Y4 and Y5 agonist). Additionally, BIIE0246 failed to alter the contractile effects of NPY in prototypical Y1 in vitro bioassays.
Taken together, these results demonstrate that BIIE0246 is a highly potent, high affinity antagonist selective for the Y2 receptor subtype. It should prove most useful to establish further the functional role of the Y2 receptor in the organism.

British Journal of Pharmacology (2000) 129, 1075–1088; doi:10.1038/sj.bjp.0703162
Differential effects of 17β‐estradiol and testosterone on the contractile responses of porcine coronary arteries
Authors: Teoh Hwee , Quan Adrian , Leung Susan W S , Man Ricky Y K 
Published: January 2005

We investigated the effects of short‐term exposure to physiological levels of 17β‐estradiol and testosterone on vasocontractile responses in porcine coronary artery rings.
Concentration‐response curves to endothelin‐1, 5‐hydroxytryptamine, the thromboxane analogue U46619 and KCl were constructed in endothelium‐intact and endothelium‐disrupted artery rings.
Thirty minutes exposure to 17β‐estradiol (1 and 30 nM) significantly attenuated vasoconstriction to endothelin‐1, 5‐hydroxytryptamine and U46619. Conversely, the same concentrations of testosterone significantly potentiated responses elicited by these contractile agents. These inhibitory effects of 17β‐estradiol and enhancing actions of testosterone on contractions were endothelium‐independent. KCl‐mediated contractions were unaffected by the presence of either sex hormones.
The oestrogen receptor antagonists, tamoxifen (10 μM) and ICI 182,780 (10 μM), were unable to reverse the inhibitory influence 1 nM 17β‐estradiol had on the agonist‐mediated contractile responses. Similarly, the androgen receptor antagonists, flutamide (10 μM) and cyproterone acetate (10 μM), failed to affect the potentiating activities of 1 nM testosterone.
The alteration in vasoconstrictive responses observed following acute exposure to either 1 nM 17β‐estradiol and 1 nM testosterone were apparent even in the presence of the protein synthesis inhibitor cycloheximide (10 μM) and the transcription inhibitor actinomycin D (10 μM).
In conclusion, we report a unique type of sex hormone action on the coronary vasculature. These events occur at low nanomolar concentrations of 17β‐estradiol and testosterone, are insensitive to conventional sex hormone receptor antagonists, are not blocked by de novo protein synthesis inhibitors and have rapid time‐courses that are uncharacteristic of classical genomic activities.

British Journal of Pharmacology (2000) 129, 1301–1308; doi:10.1038/sj.bjp.0703164
The role of lipopolysaccharide injected systemically in the reactivation of collagen‐induced arthritis in mice
Authors: Yoshino Shin , Ohsawa Motoyasu 
Published: January 2005

We investigated the role of bacterial lipopolysaccharide (LPS) in the reactivation of autoimmune disease by using collagen‐induced arthritis (CIA) in mice in which autoimmunity to the joint cartilage component type II collagen (CII) was involved.
CIA was induced by immunization with CII emulsified with complete Freund's adjuvant at the base of the tail (day 0) followed by a booster injection on day 21. Varying doses of LPS from E. coli were i.p. injected on day 50.
Arthritis began to develop on day 25 after immunization with CII and reached a peak on day 35. Thereafter, arthritis subsided gradually but moderate joint inflammation was still observed on day 50. An i.p. injection of LPS on day 50 markedly reactivated arthritis on a dose‐related fashion. Histologically, on day 55, there were marked oedema of synovium which had proliferated by the day of LPS injection, new formation of fibrin, and intense infiltration of neutrophils accompanied with a large number of mononuclear cells. The reactivation of CIA by LPS was associated with increases in anti‐CII IgG and IgG2a antibodies as well as various cytokines including IL‐12, IFN‐γ, IL‐1β, and TNF‐α. LPS from S. enteritidis, S. typhimurium, and K. neumoniae and its component, lipid A from E. coli also reactivated the disease. Polymyxin B sulphate suppressed LPS‐ or lipid A‐induced reactivation of CIA.
These results suggest that LPS may play an important role in the reactivation of autoimmune joint inflammatory diseases such as rheumatoid arthritis in humans.

British Journal of Pharmacology (2000) 129, 1309–1314; doi:10.1038/sj.bjp.0703166
Enhancement of noradrenaline release by angiotensin II and bradykinin in mouse atria: evidence for cross‐talk between Gq/11 protein‐ and Gi/o protein‐coupled receptors
Authors: Cox S L , Schelb V , Trendelenburg A U , Starke K 
Published: January 2005

The interaction between α2‐autoreceptors and receptors for angiotensin (AT1) and bradykinin (B2) was studied in mouse isolated atria. The preparations were labelled with [3H]‐noradrenaline and then superfused with desipramine‐containing medium and stimulated electrically.
Angiotensin II (10−11–10−7 M), angiotensin III (10−10–10−6 M) and bradykinin (10−11–10−7 M) enhanced the evoked overflow of tritium when preparations were stimulated with conditions that led to marked α2‐autoinhibition (120 pulses at 3 Hz), but not when stimulated with conditions that led to little α2‐autoinhibition (20 pulses at 50 Hz).
Blockade of α‐adrenoceptors by phentolamine (1 or 10 μM) reduced or abolished the effect of angiotensin II and bradykinin on the overflow response to 120 pulses at 3 Hz.
Addition of the δ‐opioid agonist [D‐Ser2]‐leucine enkephalin‐Thr (DSLET, 0.1 μM), or of neuropeptide Y (0.1 μM), together with phentolamine, restored the effect of angiotensin II and bradykinin.
The β‐adrenoceptor agonist terbutaline (10−9–10−4 M) enhanced the evoked overflow of tritium irrespective of the degree of autoinhibition.
The experiments show that (i) a marked prejunctional facilitatory effect of angiotensin and bradykinin in mouse isolated atria requires prejunctional α2‐autoinhibition; (ii) in the absence of α2‐autoinhibition, activation of other prejunctional Gi/o protein‐coupled reeptors, namely opioid and neuropeptide Y receptors, restores a marked effect of angiotensin II and bradykinin; and (iii) the facilitatory effect of terbutaline is not dependent upon the degree of α2‐autoinhibition. The findings indicate that the major part of the release‐enhancing effect elicited through prejunctional Gq/11 protein‐coupled receptors is due to disruption of an ongoing, α2‐autoreceptor‐triggered Gi/o protein mediated inhibition.

British Journal of Pharmacology (2000) 129, 1095–1102; doi:10.1038/sj.bjp.0703167