bluuebunny/crossref_metadata_2025_split huggingface dataset:
Clonidine‐induced nitric oxide‐dependent vasorelaxation mediated by endothelial α2‐adrenoceptor activation
Authors: Figueroa Xavier F , Poblete M Inés , Boric Mauricio P , Mendizábal Victoria E , Adler‐Graschinsky Edda , Huidobro‐Toro J Pablo 
Published: January 2005

To assess the involvement of endothelial α2‐adrenoceptors in the clonidine‐induced vasodilatation, the mesenteric artery of Sprague Dawley rats was cannulated and perfused with Tyrode solution (2 ml min−1). We measured perfusion pressure, nitric oxide (NO) in the perfusate using chemiluminescence, and tissue cyclic GMP by RIA.
In phenylephrine‐precontracted mesenteries, clonidine elicited concentration‐dependent vasodilatations associated to a rise in luminal NO. One hundred nM rauwolscine or 100 μM Lω‐nitro‐L‐arginine antagonized the clonidine‐induced vasodilatation. Guanabenz, guanfacine, and oxymetazoline mimicked the clonidine‐induced vasorelaxation.
In non‐contracted mesenteries, 100 nM clonidine elicited a maximal rise of NO (123±13 pmol); associated to a peak in tissue cyclic GMP. Endothelium removal, Lω‐nitro‐L‐arginine, or rauwolscine ablated the rise in NO. One hundred nM aminoclonidine, guanfacine, guanabenz, UK14,304 and oxymetazoline mimicked the clonidine‐induced surge of NO. Ten μM ODQ obliterated the clonidine‐induced vasorelaxation and the associated tissue cyclic GMP accumulation; 10 – 100 nM sildenafil increased tissue cyclic GMP accumulation without altering the clonidine‐induced NO release.
α2‐Adrenergic blockers antagonized the clonidine‐induced rise in NO. Consistent with a preferential α2D‐adrenoceptor activation, the KBs for yohimbine, rauwolscine, phentolamine, WB‐4101, and prazosin were: 6.8, 24, 19, 165, and 1489 nM, respectively.
Rat pretreatment with 100 mg kg−1 6‐hydroxydopamine reduced 95% tissue noradrenaline and 60% neuropeptide Y. In these preparations, 100 nM clonidine elicited a rise of 91.9±15.5 pmol NO. Perfusion with 1 μM guanethidine or 1 μM guanethidine plus 1 μM atropine did not modify the NO surge evoked by 100 nM clonidine.
Clonidine and congeners activate endothelial α2D‐adrenoceptors coupled to the L‐arginine pathway, suggesting that the antihypertensive action of clonidine involves an endothelial vasorelaxation mediated by NO release, in addition to presynaptic mechanisms.

British Journal of Pharmacology (2001) 134, 957–968; doi:10.1038/sj.bjp.0704320
Opposing influences of glucocorticoids and interleukin‐1β on the secretion of growth hormone and ACTH in the rat in vivo: role of hypothalamic annexin 1
Authors: Philip J G , John C D , Cover P O , Morris J F , Christian H C , Flower R J , Buckingham J C 
Published: January 2005

This study exploited established immunoneutralization protocols and an N‐terminal annexin 1 peptide (annexin 1Ac2 – 26) to advance our knowledge of the role of annexin 1 as a mediator of acute glucocorticoid action in the rat neuroendocrine system in vivo.
Rats were treated with corticosterone (500 μg kg−1, i.p.) or annexin 1Ac2 – 26 (0.1 – 10 ng rat−1, i.c.v.) and 75 min later with interleukin 1β (IL‐1β, 10 ng rat−1, i.c.v. or 500 μg kg−1, i.p). Blood was collected 1 h later for hormone immunoassay. Where appropriate, anti‐annexin 1 polyclonal antiserum (pAb) was administered subcutaneously or centrally prior to the steroid challenge.
Corticosterone did not affect the resting plasma corticotrophin (ACTH) concentration but suppressed the hypersecretion of ACTH induced by IL‐1β (i.p. or i.c.v.). Its actions were quenched by anti‐annexin 1 pAb (s.c. or i.c.v) and mimicked by annexin 1Ac2 – 26.
By contrast, corticosterone provoked an increase in serum growth hormone (GH) which was ablated by central but not peripheral administration of anti‐annexin 1 pAb. IL‐1β (i.c.v. or i.p.) did not affect basal GH but, when given centrally but not peripherally, it abolished the corticosterone‐induced hypersecretion of GH. Annexin 1Ac2 – 26 (i.c.v.) also produced an increase in serum GH which was prevented by central injection of IL‐1β.
The results support the hypothesis that the acute regulatory actions of glucocorticoids on hypothalamo‐pituitary‐adrenocortical function require annexin 1. They also provide novel evidence that the positive influence of the steroids on GH secretion evident within this timeframe is effected centrally via an annexin 1‐dependent mechanism which is antagonized by IL‐1β.

British Journal of Pharmacology (2001) 134, 887–895; doi:10.1038/sj.bjp.0704324
Mechanisms of anandamide‐induced vasorelaxation in rat isolated coronary arteries
Authors: White Richard , Vanessa Ho W ‐S , Bottrill Fiona E , Ford William R , Hiley C Robin 
Published: January 2005

The cannabinoid arachidonyl ethanolamide (anandamide) caused concentration‐dependent relaxation of 5‐HT‐precontracted, myograph‐mounted, segments of rat left anterior descending coronary artery.
This relaxation was endothelium‐independent, unaffected by the fatty acid amide hydrolase inhibitor, arachidonyl trifluoromethyl ketone (10 μM), and mimicked by the non‐hydrolysable anandamide derivative, methanandamide.
Relaxations to anandamide were attenuated by the cannabinoid receptor antagonist, SR 141716A (3 μM), but unaffected by AM 251 (1 μM) and AM 630 (1 μM), more selective antagonists of cannabinoid CB1 and CB2 receptors respectively. Palmitoylethanolamide, a selective CB2 receptor agonist, did not relax precontracted coronary arteries.
Anandamide relaxations were not affected by inhibition of sensory nerve transmission with capsaicin (10 μM) or blockade of vanilloid VR1 receptors with capsazepine (5 μM). Nevertheless capsaicin relaxed coronary arteries in a concentration‐dependent and capsazepine‐sensitive manner, confirming functional sensory nerves were present. In contrast, capsazepine and capsaicin did inhibit anandamide relaxations in methoxamine‐precontracted rat small mesenteric arteries.
Relaxations to anandamide were inhibited by TEA (1 mM) or iberiotoxin (50 nM), blockers of large conductance, Ca2+‐activated K+ channels (BKCa). Gap junction inhibition with 18α‐glycyrrhetinic acid (100 μM) did not affect anandamide relaxations.
This study shows anandamide relaxes the rat coronary artery by a novel mechanism. Anandamide‐induced relaxations do not involve the endothelium, degradation into active metabolites, or activation of cannabinoid CB1 or CB2 receptors, but may involve activation of BKCa. Vanilloid receptor activation also has no role in the effects of anandamide in coronary arteries, even though functional sensory nerves are present.

British Journal of Pharmacology (2001) 134, 921–929; doi:10.1038/sj.bjp.0704333
PKC‐ and ERK‐dependent activation of IκB kinase by lipopolysaccharide in macrophages: enhancement by P2Y receptor‐mediated CaMK activation
Authors: Chen Bing‐C , Lin Wan‐W 
Published: January 2005

Although accumulating studies have identified IκB kinase (IKK) to be essential for controlling NF‐κB activity in response to several cytokines, the upstream kinases that control IKK activity are still not completely known. We have previously reported that G protein‐coupled P2Y6 receptor activation by UTP potentiates lipopolysaccharide (LPS)‐induced IκB phosphorylation and degradation, and NF‐κB activation in J774 macrophages. In this study, we investigated the upstream kinases for IKK activation by UTP and LPS.
In murine J774 macrophages, LPS‐induced NF‐κB activation was inhibited by the presence of PDTC, D609, Ro 31‐8220, PD 098059 and SB 203580.
Accompanying NF‐κB activation, LPS induced IκB degradation and IKK activation were reduced by PDTC, D609, Ro 31‐8220 and PD 098059, but not by SB 203580.
Although UTP itself slightly induced IKK activation, this response was synergistic with LPS. BAPTA/AM and KN‐93 (a calcium/calmodulin‐dependent protein kinase (CaMK) inhibitor) attenuated UTP‐ but not LPS‐stimulated IKK activity. Synergistic IKK activation between LPS and thapsigargin was further demonstrated in peritoneal macrophages.
LPS and UTP co‐stimulation additively increased p65 NF‐κB phosphorylation. In vitro kinase assays revealed that LPS and UTP induced extracellular signal‐regulated protein kinase (ERK) and p38 mitogen‐activated protein kinase activation were respectively inhibited by PD098059 and SB 203580.
Taken together, we demonstration that Gq protein‐coupled P2Y6 receptor activation can potentiate LPS‐stimulated IKK activity. While PKC and ERK participate in IKK activation by LPS and UTP, the phosphatidylinositide‐phospholipase C‐dependent activation of CaMK plays a major role in UTP potentiation of the LPS response.

British Journal of Pharmacology (2001) 134, 1055–1065; doi:10.1038/sj.bjp.0704334
Release of non‐neuronal acetylcholine from the isolated human placenta is mediated by organic cation transporters
Authors: Wessler Ignaz , Roth Elisabeth , Deutsch Carola , Brockerhoff Peter , Bittinger Fernando , Kirkpatrick Charles James , Kilbinger Heinz 
Published: January 2005

The release of acetylcholine was investigated in the human placenta villus, a useful model for the characterization of the non‐neuronal cholinergic system.
Quinine, an inhibitor of organic cation transporters (OCT), reduced acetylcholine release in a reversible and concentration‐dependent manner with an IC50 value of 5 μM. The maximal effect, inhibition by 99%, occurred at a concentration of 300 μM.
Procaine (100 μM), a sodium channel blocker, and vesamicol (10 μM), an inhibitor of the vesicular acetylcholine transporter, were ineffective.
Corticosterone, an inhibitor of OCT subtype 1, 2 and 3 reduced acetylcholine in a concentration‐dependent manner with an IC50 value of 2 μM.
Substrates of OCT subtype 1, 2 and 3 (amiloride, cimetidine, guanidine, noradrenaline, verapamil) inhibited acetylcholine release, whereas carnitine, a substrate of subtype OCTN2, exerted no effect.
Long term exposure (48 and 72 h) of villus strips to anti‐sense oligonucleotides (5 μM) directed against transcription of OCT1 and OCT3 reduced the release of acetylcholine, whereas OCT2 anti‐sense oliogonucleotides were ineffective.
It is concluded that the release of non‐neuronal acetylcholine from the human placenta is mediated via organic cation transporters of the OCT1 and OCT3 subtype.

British Journal of Pharmacology (2001) 134, 951–956; doi:10.1038/sj.bjp.0704335
Reciprocal regulation of cyclic GMP content by cyclic GMP‐phosphodiesterase and guanylate cyclase in SHR with CsA‐induced nephrotoxicity
Authors: Hosogai Naomi , Seki Jiro , Goto Toshio 
Published: January 2005

The effect of the immunosuppressant drug, cyclosporin A (CsA), on the nitric oxide (NO)‐cyclic GMP pathway was examined in spontaneous hypertensive rats (SHR).
CsA (50 mg kg−1) treatment for 14 days induced typical CsA nephrotoxicity, which was characterized by morphological changes in the glomerulus and proximal tubule as well as an abnormality of creatinine clearance, FENa and BUN.
CsA significantly decreased both NOS activity in the kidney and NOx contents in urine, but significantly increased cyclic GMP content in the kidney.
A marked change in two kinds of enzyme, which contribute towards the increase in cyclic GMP in tissue, namely, a decrease in cyclic GMP‐phosphodiesterase activity and increase in guanylate cyclase activity, was observed in the kidney treated with CsA.
In the isolated perfused kidney, a decreased in perfusion pressure induced by SNP in the kidney isolated from CsA group was significantly greater than that of control.
There seem to exist a reciprocal mechanism to maintain cyclic GMP content via both a decrease in cyclic GMP degradation and an increase in synthesis of cyclic GMP in the kidney treated with CsA. This mechanism is likely to be playing an important role to regulate the homeostasis in the kidney with CsA nephrotoxicity.

British Journal of Pharmacology (2001) 134, 995–1002; doi:10.1038/sj.bjp.0704337
Quantitative aspects of the inhibition by NG‐monomethyl‐L‐arginine of responses to endothelium‐dependent vasodilators in human forearm vasculature
Authors: Dawes M , Chowienczyk P J , Ritter J M 
Published: January 2005

NG‐monomethyl‐L‐arginine (L‐NMMA) constricts human forearm resistance vasculature and selectively attenuates vasodilator responses to endothelium‐dependent vasodilators. Incomplete inhibition of such responses could be due to an inadequate dose of L‐NMMA or to NO‐independent vasodilator mechanisms.
This study sought to determine doses of L‐NMMA that are maximally effective in reducing basal and stimulated forearm blood flow. Drugs were infused via the brachial artery in 32 healthy men. Acetylcholine (11 – 330 nmol min−1) was compared with albuterol (0.33 – 10 nmol min−1), and nitroprusside (1.7 – 20 nmol min−1).
The effect of L‐NMMA on basal flow approached maximum (53±2% reduction) at a dose of 16 μmol min−1. L‐NMMA (16 μmol min−1) did not significantly influence responses to nitroprusside, but antagonized acetylcholine and albuterol (each P<0.001, by repeated measures analysis of variance).
Inhibition of acetylcholine by L‐NMMA (16 μmol min−1) was strongly influenced by acetylcholine dose (73±7% inhibition at 11 nmol min−1, P<0.01; 4±11% inhibition at 330 nmol min−1, P=NS, Student's paired t‐test). Significant inhibition of albuterol was observed at all doses.
A higher dose of L‐NMMA (64 μmol min−1) did not significantly inhibit the response to acetylcholine (330 nmol min−1). Responses to this dose of acetylcholine were unaffected by a cyclo‐oxygenase (COX) inhibitor (indometacin) alone but combined COX and NO inhibition attenuated acetylcholine responses by 42±19%, implying that there is a compensatory increase in the contribution of prostaglandins or NO to acetylcholine‐induced dilatation when one or other pathway is inhibited.

British Journal of Pharmacology (2001) 134, 939–944; doi:10.1038/sj.bjp.0704338
Inhibitory effect of palmitoylethanolamide on gastrointestinal motility in mice
Authors: Capasso Raffaele , Izzo Angelo A , Fezza Filomena , Pinto Aldo , Capasso Francesco , Mascolo Nicola , Di Marzo Vincenzo 
Published: January 2005

We have studied the effect of palmitoylethanolamide (PEA, 2.5 – 30 mg kg−1, i.p.) on upper gastrointestinal transit in control mice and in mice with chronic intestinal inflammation induced by croton oil.
PEA significantly and dose‐dependently decreased intestinal transit. The inhibitory effect of PEA (10 mg kg−1) was not modified by the cannabinoid CB1 receptor antagonist SR141716A (0.3 mg kg−1, i.p.), the cannabinoid CB2 receptor antagonist SR144528 (1 mg kg−1, i.p.), NG‐nitro‐L‐arginine methyl ester (L‐NAME, 25 mg kg−1, i.p.), yohimbine (1 mg kg−1, i.p.), naloxone (2 mg kg−1, i.p.) or hexamethonium (1 mg kg−1, i.p.).
PEA levels were significantly decreased in the small intestine of croton oil‐treated mice. In these animals, PEA also inhibited motility and this effect was not counteracted by SR141716A (0.3 mg kg−1), or SR144528 (1 mg kg−1).
Pre‐treatment of mice with the amidase inhibitor phenylmethyl sulphonil fluoride (PMSF, 30 mg kg−1, i.p.) did not modify the inhibitory effect of PEA, either in control or in mice with inflammation.
It is concluded that PEA inhibits intestinal motility with a peripheral mechanism independent from cannabinoid receptor activation. The decreased levels of PEA in croton oil‐treated might contribute, at least in part, to the exaggerated transit observed during chronic intestinal inflammation.

British Journal of Pharmacology (2001) 134, 945–950; doi:10.1038/sj.bjp.0704339
Anandamide‐induced relaxation of sheep coronary arteries: the role of the vascular endothelium, arachidonic acid metabolites and potassium channels
Authors: Grainger J , Boachie‐Ansah G 
Published: January 2005

The effects of the endocannabinoid, anandamide, and its metabolically stable analogue, methanandamide, on induced tone were examined in sheep coronary artery rings in vitro.
In endothelium‐intact rings precontracted to the thromboxane A2 mimetic, U46619, anandamide (0.01 – 30 μM) induced slowly developing concentration‐dependent relaxations (pEC50 [negative log of EC50]=6.1±0.1; Rmax [maximum response]=81±4%). Endothelium denudation caused a 10 fold rightward shift of the anandamide concentration‐relaxation curve without modifying Rmax. Methanandamide was without effect on U46619‐induced tone.
The anandamide‐induced relaxation was unaffected by the cannabinoid receptor antagonist, SR 141716A (3 μM), the vanilloid receptor antagonist, capsazepine (3 and 10 μM) or the nitric oxide synthase inhibitor, L‐NAME (100 μM).
The cyclo‐oxygenase inhibitor, indomethacin (3 and 10 μM) and the anandamide amidohydrolase inhibitor, PMSF (70 and 200 μM), markedly attenuated the anandamide response. The anandamide transport inhibitor, AM 404 (10 and 30 μM), shifted the anandamide concentration‐response curve to the right.
Precontraction of endothelium‐intact rings with 25 mM KCl attenuated the anandamide‐induced relaxations (Rmax=7±7%), as did K+ channel blockade with tetraethylammonium (TEA; 3 μM) or iberiotoxin (100 nM). Blockade of small conductance, Ca2+‐activated K+ channels, delayed rectifier K+ channels, KATP channels or inward rectifier K+ channels was without effect.
These data suggest that the relaxant effects of anandamide in sheep coronary arteries are mediated in part via the endothelium and result from the cellular uptake and conversion of anandamide to a vasodilatory prostanoid. This, in turn, causes vasorelaxation, in part, by opening potassium channels.

British Journal of Pharmacology (2001) 134, 1003–1012; doi:10.1038/sj.bjp.0704340
Structure‐activity relationships of diadenosine polyphosphates (ApnAs), adenosine polyphospho guanosines (ApnGs) and guanosine polyphospho guanosines (GpnGs) at P2 receptors in the rat mesenteric arterial bed
Authors: Ralevic Vera , Jankowski Joachim , Schlüter Hartmut 
Published: January 2005

Vascular effects of diadenosine polyphosphates (ApnAs), adenosine polyphospho guanosines (ApnGs) and guanosine polyphospho guanosines (GpnGs), novel families of naturally‐occurring signalling molecules, were investigated in methoxamine preconstricted rat isolated perfused mesenteric arterial beds.
Three different types of response were elicited by ApnAs and ApnGs. Those with a short polyphosphate chain (n=2 – 3) elicited vasorelaxation. Ap3A was more potent than Ap2A, and both were more potent than the corresponding ApnG. Relaxations to Ap3A and Ap3G, but not to Ap2A and Ap2G, were blocked by endothelium removal and pyridoxalphosphate‐6‐azophenyl‐2′,4′‐disulphonic acid (PPADS), a P2 receptor antagonist.
Longer polyphosphate chain ApnAs and ApnGs (n=4 – 6) elicited dose‐dependent vasoconstriction followed by prolonged vasorelaxation, with a potency order for both types of response of Ap5AAp6A>Ap4A. A similar order and potency was observed for ApnGs. Contractions and prolonged relaxations were blocked by PPADS and P2X1 receptor desensitization with α,β‐methylene ATP (α,β‐meATP), and were largely endothelium‐independent.
In the presence of α,β‐meATP rapid relaxations to contractile ApnAs and ApnGs (n=4 – 6) were revealed.
GpnGs were virtually inactive, except for Gp2G which elicited vasoconstriction via PPADS‐ and α,β‐meATP‐sensitive smooth muscle P2X1‐like receptors.
These data show that, as with ApnAs, the length of the polyphosphate chain (n) is an important determinant of the activity of ApnGs at P2 receptors in the rat mesenteric arterial bed. When the chain is short (n=2 – 3) the purines elicit rapid vasorelaxation, which for Ap3A and Ap3G is mediated via endothelial P2Y1‐like receptors. When the chain is long (n=4 – 6) ApnAs and ApnGs elicit vasoconstriction via P2X1‐like receptors, followed by prolonged endothelium‐independent vasorelaxation. Rapid relaxation to contractile dinucleotides (n=4 – 6) is revealed by block of vasoconstriction. Regarding the purine moiety, one adenine is crucial and sufficient for vasoactivity as GpnGs were largely inactive, and ApnAs and ApnGs approximately equipotent.

British Journal of Pharmacology (2001) 134, 1073–1083; doi:10.1038/sj.bjp.0704341
Protein kinase C involvement in aloe‐emodin‐ and emodin‐induced apoptosis in lung carcinoma cell
Authors: Lee Hong‐Zin 
Published: January 2005

This study demonstrated aloe‐emodin‐ and emodin‐induced apoptosis in lung carcinoma cell lines CH27 (human lung squamous carcinoma cell) and H460 (human lung non‐small cell carcinoma cell). Aloe‐emodin‐ and emodin‐induced apoptosis was characterized by nuclear morphological changes and DNA fragmentation.
During apoptosis, an increase in cytochrome c of cytosolic fraction and activation of caspase‐3, identified by the cleavage of its proform, were observed.
To elucidate whether the expression of protein kinase C (PKC) isozymes are involved in aloe‐emodin‐ and emodin‐induced apoptosis, this study examined the changes of PKC isozymes by Western blotting techniques during aloe‐emodin‐ and emodin‐induced apoptosis.
The expression of PKC isozymes involved in aloe‐emodin‐ and emodin‐induced apoptosis of CH27 and H460 cells. In this study, aloe‐emodin and emodin induced the changes of each of PKC isozymes in CH27 and H460 cells.
The decrease in the expression of PKCδ and ε may play a critical role in aloe‐emodin‐ and emodin‐induced apoptosis in CH27 and H460 cells.
The present study also demonstrated that PKC stimulation occurs at a site downstream of caspase‐3 in the emodin‐mediated apoptotic pathway.

British Journal of Pharmacology (2001) 134, 1093–1103; doi:10.1038/sj.bjp.0704342
Role of von Willebrand factor in tumour cell‐induced platelet aggregation: differential regulation by NO and prostacyclin
Authors: Jurasz Paul , Stewart Michael W , Radomski Anna , Khadour Fadi , Duszyk Marek , Radomski Marek W 
Published: January 2005

We have studied the effects of a novel agonist, solid‐phase von Willebrand Factor (sVWF), on tumour cell‐induced platelet aggregation (TCIPA).
Washed platelet suspensions were obtained from human blood and the effects of HT‐1080 human fibrosarcoma cells and sVWF on platelets were studied using aggregometry, phase‐contrast microscopy, and flow cytometry.
Incubation of platelets with sVWF (1.2 μg ml−1) and HT‐1080 cells (5×103 ml−1) resulted in a two‐phased reaction characterized first by the adhesion of platelets to sVWF, then by aggregation.
TCIPA in the presence of sVWF was inhibited by S‐nitroso‐glutathione (GSNO, 100 μM) and prostacyclin (PGI2, 30 nM).
Platelet activation in the presence of tumour cells and sVWF resulted in the decreased surface expression of platelet glycoprotein (GP)Ib and up‐regulation of GPIIb/IIIa receptors.
Pre‐incubation of platelets with PGI2 (30 nM) resulted in inhibition of sVWF‐tumour cell‐stimulated platelet surface expression of GPIIb/IIIa as measured by flow cytometry using antibodies directed against both non‐activated and activated receptor. In contrast, GSNO (100 μM) did not affect sVWF‐tumour cell‐stimulated platelet surface expression of GPIIb/IIIa.
Flow cytometry performed with PAC‐1 antibodies that bind only to the activated GPIIb/IIIa revealed that GSNO (100 μM) caused inhibition of activation of GPIIb/IIIa.
The inhibitors exerted no significant effects on TCIPA‐mediated changes in GPIb.
Thus, sVWF potentiates the platelet‐aggregatory activity of HT‐1080 cells and these effects appear to be mediated via up‐regulation of platelet GPIIb/IIIa.
Prostacyclin and NO inhibit TCIPA‐sVWF‐mediated platelet aggregation. The mechanisms of inhibition of this aggregation by PGI2 differ from those of NO.

British Journal of Pharmacology (2001) 134, 1104–1112; doi:10.1038/sj.bjp.0704343