bluuebunny/crossref_metadata_2025 huggingface dataset:
Dissociation of lipopolysaccharide‐mediated induction of nitric oxide synthase and inhibition of DNA synthesis in RAW 264.7 macrophages and rat aortic smooth muscle cells
Authors: Paul Andrew , Bryant Clare , Lawson Mark F. , Chilvers Edwin R. , Plevin Robin
Published: August 2006

The active component of endotoxin, lipopolysaccharide (LPS), inhibited basal DNA synthesis in both RAW 264.7 macrophages (IC50 0.05±0.03 μg ml−1) and rat aortic smooth muscle cells (RASMC) (IC50 9.7±0.4 μg ml−1).

In both cell types, serum differentially affected LPS‐stimulated inhibition of DNA synthesis. In RAW 264.7 macrophages the presence of serum reduced the IC50 for LPS‐stimulated inhibition of DNA synthesis (1.4±0.85 ng ml−1). However, in RASMC serum stimulated DNA synthesis and further increased the IC50 value for LPS‐stimulated inhibition of thymidine incorporation (57.3±7.8 μg ml−1).

LPS also stimulated the induction of nitric oxide synthase (NOS) in RAW 264.7 macrophages with maximal expression at concentrations of 13 μg ml−1. This was wholly dependent upon the presence of serum. In RASMC LPS alone, up to concentrations of 100 μg ml−1, did not induce nitric oxide synthase and required co‐incubation with the direct activator of adenylyl cyclase, forskolin. Under these conditions stimulated expression of NOS was inhibited by the presence of serum.

Incubation with the nitric oxide synthase inhibitors Nω‐nitro‐l‐arginine methyl ester (l‐NAME) and l‐canavanine did not reverse the inhibition of [3H]‐thymidine incorporation in response to LPS but prevented the formation of nitrite in both cell types.

These results indicate that the effects of LPS upon cell growth are independent of the induction of the 130 kDa isoform of nitric oxide synthase and nitric oxide formation in both RAW 264.7 macrophages and RASMC.

British Journal of Pharmacology (1997) 120, 1439–1444; doi:10.1038/sj.bjp.0701070
Differential effects of ω‐conotoxin GVIA on cholinergic and non‐cholinergic secretomotor neurones in the guinea‐pig small intestine
Authors: Vremec Melinda A , Bornstein Joel C , Wright Christine E , Humphrey Andrea
Published: August 2006

Ussing chambers were used to study the effects of the specific N‐type Ca2+ channel antagonist, ω‐conotoxin GVIA, on neurally evoked secretion across isolated submucosa/mucosa preparations from the small intestine of the guinea‐pig.

Cholinergic and non‐cholinergic neurones were stimulated with 10 μM dimethylphenylpiperazinium (DMPP). Non‐cholinergic secretomotor neurones were preferentially stimulated with 100 nM 5‐hydroxytryptamine (5‐HT), while cholinergic secretomotor neurones were preferentially stimulated with 3 μM 5‐HT in the presence of the 5‐HT2 receptor antagonist ketanserin (30 nM).

ω‐Conotoxin GVIA (1 nM–1 μM) depressed the secretion evoked by DMPP in a concentration‐dependent manner, but a substantial residual response was observed. Hyoscine (100 nM) significantly depressed secretion evoked by DMPP, but did not prevent further depression of secretion by ω‐conotoxin GVIA.

The toxin was substantially more effective when the non‐cholinergic secretomotor neurones were preferentially activated with 100 nM 5‐HT, with a decrease in the response of more than 75% of the control value in the presence of 1 μM ω‐conotoxin GVIA.

ω‐Conotoxin GVIA (1 μM) was relatively ineffective against secretion evoked by preferential activation of cholinergic secretomotor neurones with 3 μM 5‐HT in the presence of 30 nM ketanserin, inhibiting the response by less than 33%. However, this inhibition was significant. Both 100 nM hyoscine and 300 nM tetrodotoxin abolished this effect of ω‐conotoxin GVIA.

It is concluded that N‐type Ca2+ channels play a major role in transmitter release from non‐cholinergic secretomotor neurones, but are not important for release from cholinergic secretomotor neurones in the guinea‐pig small intestine.

British Journal of Pharmacology (1997) 121, 232–236; doi:10.1038/sj.bjp.0701071
Effects of KRN4884, a novel pyridinecarboxamidine type KATP channel opener, on serum triglyceride levels in rats
Authors: Yokoyama Takashi , Izumi Hideakira , Endoh Megumi , Izawa Toshio , Ogawa Nobuyuki , Okada Yuji
Published: August 2006

The effects of KRN4884, a novel pyridinecarboxamidine type KATP channel opener, on serum triglyceride levels were investigated in Sprague‐Dawley rats.

Oral administration of KRN4884 (3 mg kg−1) for 10 days caused a significant reduction in serum triglyceride levels, which was comparable to that of clofibrate (160 mg kg−1). Reduction in serum triglyceride levels by KRN4884 and clofibrate were accompanied by a reduction in triglyceride levels both in chylomicron and in very low density lipoprotein. KRN4884 treatment did not affect serum concentrations of total cholesterol and phospholipid, but did increase free fatty acid levels. Clofibrate reduced total cholesterol, phospholipid and free fatty acid levels.

Administration of clofibrate significantly decreased triglyceride secretion rate as measured by the Triton WR‐1339 injection procedure, while KRN4884 did not.

Rats receiving KRN4884 exhibited an increase in lipoprotein lipase (LPL) activity both in adipose tissue and in skeletal muscle. There was an inverse correlation between serum triglyceride levels and tissue LPL activities. KRN4884 did not change hepatic triglyceride lipase (HTGL) activity. Clofibrate affected neither LPL nor HTGL activities.

It is concluded that administration of KRN4884 results in reduced serum triglyceride levels which may be due to the enhancement of LPL activity in peripheral tissues.

British Journal of Pharmacology (1997) 120, 1471–1476; doi:10.1038/sj.bjp.0701077
The isoquinoline derivative KN‐62 a potent antagonist of the P2Z‐receptor of human lymphocytes
Authors: Gargett Caroline E. , Wiley James S.
Published: August 2006

Extracellular adenosine 5′‐triphosphate (ATP) is an agonist for a P2Z receptor on human lymphocytes which mediates opening of a cation‐selective ion channel, activation of phospholipase D and shedding of the adhesion molecule, L‐selectin, from the cell surface. The isoquinolinesulphonamides, KN‐62, (1‐[N, O‐bis(5‐isoquinolinesulphonyl)‐N‐methyl‐L‐tyrosyl]‐ 4‐phenylpiperazine), a selective antagonist of Ca2+/calmodulin‐dependent protein kinase II (CaMKII), and KN‐04, (N‐[1‐[N‐methyl‐p‐(5 isoquinoline sulphonyl)benzyl]‐2‐(4 phenylpiperazine)ethyl]‐5‐isoquinolinesulphonamide) an inactive analogue, were used to investigate the possible role of CaMKII in these diverse effects of extracellular ATP.

KN‐62 potently antagonized ATP‐stimulated Ba2+ influx into fura‐2 loaded human lymphocytes with an IC50 of 12.7±1.5 nm (n=3) and complete inhibition of the flux at a concentration of 500 nm. Similarly, KN‐62 inhibited ATP‐stimulated ethidium+ uptake, measured by time resolved flow cytometry, with an IC50 of 13.1±2.6 nm (n=4) and complete inhibition of the flux at 500 nm.

KN‐04 antagonized ATP‐stimulated Ba2+ influx with an IC50 of 17.3±2.7 nm (n=3). Similarly, KN‐04 inhibited ATP‐stimulated ethidium+ uptake with an IC50 of 37.2±8.9 nm (n=4). Both fluxes were completely inhibited at 500 nm KN‐04.

ATP‐stimulated phospholipase D activity, measured in [3H]‐oleic acid‐labelled lymphocytes by the transphosphatidylation reaction, was antagonized by KN‐62 and KN‐04, with 50% inhibition at 5.9±1.2 and 9.7±2.8 nm (n=3), respectively. Both KN‐62 and KN‐04 inhibited ATP‐stimulated shedding of L‐selectin, measured by flow cytometric analysis of cell surface L‐selectin, with IC50 values of 31.5±4.5 and 78.7±10.8 nm (n=3), respectively. Neither of the isoquinolinesulphonamides (500 nm) inhibited phorbol ester‐ or ionomycin‐stimulated phospholipase D activity or phorbol ester‐induced shedding of L‐selectin.

The inhibitory effect of KN‐62 or KN‐04 on P2Z‐mediated responses was slow in onset (5 min) and only partially reversed by washing the cells.

Both KN‐62 and KN‐04 (at 500 nm) had no effect on uridine 5′‐triphosphate (UTP)‐stimulated Ca2+ transients in fura‐2 loaded human neutrophils, a response which is mediated by the P2Y2 receptor.

Thus, KN‐62 and KN‐04 are potent antagonists of the P2Z receptor and at nanomolar concentrations inhibit all known responses mediated by the P2Z receptor of human lymphocytes. In contrast, KN‐62 and KN‐04 had no effect on responses mediated by the P2Y2 receptor of neutrophils. Moreover, since KN‐62 and KN‐04 are almost equipotent, the P2Z‐mediated responses do not involve CaMKII, but indicate that the isoquinolinesulphonamides are potent and direct inhibitors of the P2Z‐receptor.

British Journal of Pharmacology (1997) 120, 1483–1490; doi:10.1038/sj.bjp.0701081
Paradoxical action of the cannabinoid WIN 55,212‐2 in stimulated and basal cyclic AMP accumulation in rat globus pallidus slices
Authors: Maneuf Yannick P. , Brotchie Jonathan M.
Published: August 2006

The effects of the synthetic cannabinoid WIN 55,212‐2 on forskolin‐stimulated and basal adenosine 3′ : 5′‐cyclic monophosphate (cyclic AMP) accumulation in globus pallidus slices were investigated. WIN 55,212‐2 caused a concentration‐dependent decrease in forskolin‐stimulated cyclic AMP accumulation in globus pallidus slices (maximum inhibition 36% for 30 μm). This effect was blocked by the cannabinoid receptor antagonist SR 141716A (100 μm). WIN 55,212‐2 alone caused a concentration‐dependent increase in cyclic AMP levels in unstimulated slices (maximum increase 52.6% for 100 μm). This effect was also blocked by SR 141716A (100 μm). In either forskolin‐stimulated or unstimulated conditions SR 1417161A (100 μm) did not affect cyclic AMP levels.

British Journal of Pharmacology (1997) 120, 1397–1398; doi:10.1038/sj.bjp.0701101
The effect of okadaic acid on non‐adrenergic non‐cholinergic contraction in guinea‐pig isolated bronchus
Authors: Harrison S , Spina D , Page C P
Published: August 2006

We have investigated the role of phosphatases in modulating contractile responses to electrical field stimulation (EFS), methacholine, substance P and capsaicin in guinea‐pig isolated main bronchus by use of the phosphatase 1 and 2A inhibitor okadaic acid.

Non‐adrenergic non‐cholinergic (eNANC) contractile responses were elicited by EFS (3 Hz, 20 s, 0.5 ms max. voltage) in the guinea‐pig isolated main bronchus in the presence of the non‐selective muscarinic antagonist, atropine (1 μM), the non‐selective β‐adrenoceptor antagonist, propranolol (1 μM), the neutral endopeptidase inhibitor thiorphan (10 μM) and the cyclo‐oxygenase inhibitor, indomethacin (5 μM). Okadaic acid significantly attenuated eNANC contractile responses (% inhibition) elicited by EFS (0.01 μM, 15.2±26.9%; 0.03 μM, 30.4±13.9%; 0.01 μM, 39.8±5.1%; 0.3 μM, 59.5±8.7%; 1 μM 77.8±7.8%; P<0.05, n=4). In contrast, the inactive analogue 1‐Nor okadaone (0.3 μM) failed to attenuate significantly eNANC contractile responses (% inhibition elicited by 1‐Nor okadaone, −1.25±8.5% vs dimethylsulphoxide (DMSO), −13.5±21.5%; P>0.05, n=4).

Cholinergic contractile responses were elicited by EFS (1–30 Hz, 10 s, 0.5 ms max. voltage) in guinea‐pig isolated bronchus in the presence of the nitric oxide synthase inhibitor, Nω‐nitro‐L‐arginine methyl ester (L‐NAME, 30 μM). Okadaic acid failed to attenuate significantly the contractile (% methacholine Emax) response elicited by EFS at all frequencies tested compared with the control (1 Hz, control, 22±7.9% vs okadaic acid, 18±7.7%; 3 Hz, control, 26±6.9% vs okadaic acid, 27±9.1%; 10 Hz, control, 36±7.6% vs okadaic acid, 33±8.9%; 30 Hz, control, 50±7.6% vs okadaic acid, 42±14%; P>0.05, n=4).

Okadaic acid (0.3 μM) failed to alter significantly the contractile potency (pD2) to capsaicin (okadaic acid, 9.0±0.5, vs DMSO, 9.2±0.4; P>0.05 n=6), substance P (okadaic acid, 7.6±0.3 vs DMSO, 8.2±0.2; P>0.05 n=7) or methacholine (okadaic acid, 6.4±0.2 vs DMSO, 6.4±0.3; P>0.05 n=4).

Okadaic acid (0.01–1 μM) did not appear to reverse substance P‐induced tone. The maximal relaxant response (% reversal of substance P‐induced tone) mediated by okadaic acid (1 μM) was 33±11.7% (n=4), this was not significantly different from the DMSO (0.8%) or a time‐dependent fall in tone of 34.3±23.1% (n=4) and 33±15.8% (n=4), respectively. Okadaic acid (0.3 μM) failed to augment isoprenaline‐induced relaxation repsonses in substance P contracted bronchus (okadaic acid, 6.5±0.4 vs DMSO, 5.9±0.3; P>0.05, n=9).

These results indicate that protein phosphatases appear to regulate the release of sensory neuropeptides from airway sensory nerves in response to electrical field stimulation.

British Journal of Pharmacology (1997) 121, 181–186; doi:10.1038/sj.bjp.0701114
KATP‐channel on the somata of spiny neurones in rat caudate nucleus: regulation by drugs and nucleotides
Authors: Schwanstecher Christina , Bassen Dagmar
Published: August 2006

The aim of the present study was to characterize the pharmacological properties of the adenosine 5′‐triphosphate(ATP)‐sensitive K+ channel (KATP‐channel) on the somata of spiny neurones in rat caudate nucleus and to compare them with those of β‐cells. For that purpose we tested the effects of several KATP‐channel‐inhibiting and ‐activating drugs on the opening activity of the KATP‐channel in caudate nucleus by use of the patch‐clamp technique. In addition, the modulation of drug responses by cytosolic nucleotides was examined.

When KATP‐channels in caudate nucleus were activated in cell‐attached patches by inhibition of mitochondrial energy production, meglitinide (a benzoic acid derivative), Hoe36320 (a sulphonylurea of low lipophilicity) and glipizide reduced KATP‐channel activity half‐maximally at 0.4 μM, 0.4 μM and about 0.5 nM, respectively.

In inside‐out patches (presence of 0.7 mM free Mg2+ at the cytoplasmic membrane side), tolbutamide (0.1 mM) caused only partial inhibition of KATP‐channels in the absence of cytosolic nucleotides but complete inhibition in the simultaneous presence of the channel‐activating nucleotide guanosine 5′‐diphosphate (GDP; 1 mM) and the channel‐inhibiting nucleotide adenylyl‐imidodiphosphate (AMP‐PNP; 0.2 mM).

Diazoxide (0.3 mM) strongly increased channel activity in the presence of ATP (0.1 mM) or GDP (0.03 mM), but was ineffective in the presence of AMP‐PNP (0.1 mM). In the absence of cytosolic nucleotides diazoxide even decreased channel activity.

In the presence of 0.1 mM ATP, diazoxide activated KATP‐channels half‐maximally at 38 μM.

When KATP‐channel activity was inhibited by 0.1 mM ATP, (−)‐pinacidil (0.5 mM) elicited a slight activation of KATP‐channels in caudate nucleus, whereas (+)‐pinacidil (0.5 mM) and lemakalim (0.3 mM) were ineffective.

Since our data indicate similar control by drugs and nucleotides of KATP‐channels in the somata of spiny neurones and pancreatic β‐cells, we conclude that the high affinity sulphonylurea receptors of these tissues are probably closely related.

British Journal of Pharmacology (1997) 121, 193–198; doi:10.1038/sj.bjp.0701120
Antinociceptive and immunosuppressive effects of opiate drugs: a structure‐related activity study
Authors: Sacerdote Paola , Manfredi Barbara , Mantegazza Paolo , Panerai Alberto E.
Published: August 2006

Although it is well known that morphine induces significant immunosuppression, the potential immunosuppressive activity of morphine derived drugs commonly used in the treatment of pain (codeine, hydromorphone, oxycodone) has never been evaluated.

We evaluated in the mouse the effect of the natural opiates (morphine and codeine) and synthetic derivatives (hydromorphone, oxycodone, nalorphine, naloxone and naltrexone) on antinociceptive thresholds and immune parameters (splenocyte proliferation, Natural Killer (NK) cell activity and interleukin‐2 (IL‐2) production).

Morphine displayed a potent immunosuppressive effect that was not dose‐related to the antinociceptive effect, codeine possessed a weak antinociceptive effect and limited immunosuppressive activity; nalorphine, a μ‐antagonist and κ‐agonist, exerted a potent immunosuppressive effect, but had very weak antinociceptive activity. The pure κ‐antagonist nor‐BNI antagonized the antinociceptive, but not the immunosuppresive effect of nalorphine.

Hydromorphone and oxycodone, potent antinociceptive drugs, were devoid of immunosuppressive effects.

The pure antagonists naloxone and naltrexone potentiated immune responses.

Our data indicate that the C6 carbonyl substitution, together with the presence of a C7‐8 single bond potentiates the antinociceptive effect, but abolishes immunosuppression (hydromorphone and oxycodone).

The single substitution of an allyl on the piperidinic ring resulted in a molecule that antagonized the antinociceptive effect but maintained the immunosuppressive effect.

Molecules that carry modifications of C6, the C7‐8 bond and C14, together with an allyl or caboxymethyl group on the piperidinic ring antagonized both the antinociceptive and the immunosuppressive effect of opiates and were themselves immunostimulants.

British Journal of Pharmacology (1997) 121, 834–840; doi:10.1038/sj.bjp.0701138
A neuromodulatory role for neuronal nitric oxide in the rabbit renal artery
Authors: Vials Amanda J , Crowe Rahima , Burnstock Geoffrey
Published: August 2006

The effects of the nitric oxide synthase inhibitor NG‐nitro‐L‐arginine methyl ester (L‐NAME) on vasoconstrictor responses to transmural electrical nerve stimulation and noradrenaline were examined in the rabbit isolated renal artery with and without an intact endothelium. In addition, the effect of removing the endothelium from the renal artery on vasoconstrictor responses to transmural electrical nerve stimulation and noradrenaline was also investigated. Immunohistofluorescence techniques were carried out to determine if there were any nitrergic nerves supplying the renal artery.

The vasoconstriction produced in response to transmural electrical nerve stimulation (2–64 Hz) was significantly enhanced in the presence of L‐NAME (3×10−6, 10−5, 3×10−5 and 10−4 M).

L‐NAME (3×10−6, 10−5, 3×10−5 and 10−4 M) did not significantly affect the maximum vasoconstriction produced in response to noradrenaline. However, the noradrenaline dose‐response curve was significantly shifted to the left by the addition of L‐NAME (3×10−6, 10−5, 3×10−5 and 10−4 M).

The increase in the amplitude of the vasoconstriction, produced in response to transmural electrical nerve stimulation (16 Hz) and noradrenaline (10−5 M) in the presence of L‐NAME (10−5 M) was not observed when L‐arginine (10−3 M) was added in addition to L‐NAME (10−5 M).

Removing the endothelium did not significantly affect the response to transmural electrical nerve stimulation (1–64 Hz). The maximum vasoconstriction in response to noradrenaline was also unaffected by the removal of the endothelium. The pD2 value for noradrenaline obtained from vessels with no endothelium was significantly greater than the pD2 value obtained from vessels with an intact endothelium (5.90±0.11 and 5.16±0.03, respectively).

On renal artery segments with no endothelium L‐NAME (3×10−5 M) significantly enhanced the response to transmural electrical nerve stimulation (2–64 Hz). L‐NAME did not affect the maximum response to noradrenaline. However, there was a significant shift to the right of the noradrenaline dose‐response curve in the presence of L‐NAME (3×10−5 M).

Both nitric oxide synthase‐containing and NADPH‐diaphorase stained nerves were located on the adventitial‐medial border of the rabbit renal artery.

The present study has suggested a presynaptic inhibitory action for nitric oxide (probably derived from identified perivascular nitrergic nerves), on perivascular sympathetic vasoconstrictor nerve mediated responses of the rabbit renal artery. In contrast, the enhancement of the response to noradrenaline by L‐NAME can be attributed to inhibition of the synthesis of endothelium‐derived nitric oxide.

British Journal of Pharmacology (1997) 121, 213–220; doi:10.1038/sj.bjp.0701141
Interactions between imidazoline compounds and sulphonylureas in the regulation of insulin secretion
Authors: Mourtada Mirna , Brown Colin A. , Smith Stephen A. , Piercy Valerie , Chan Susan L. F. , Morgan Noel G.
Published: August 2006

Imidazoline α2‐antagonist drugs such as efaroxan have been shown to increase the insulin secretory response to sulphonylureas from rat pancreatic B‐cells. We have investigated whether this reflects binding to an islet imidazoline receptor or whether α2‐adrenoceptor antagonism is involved.

Administration of (±)‐efaroxan or glibenclamide to Wistar rats was associated with a transient increase in plasma insulin. When both drugs were administered together, the resultant increase in insulin levels was much greater than that obtained with either drug alone.

Use of the resolved enantiomers of efaroxan revealed that the ability of the compound to enhance the insulin secretory response to glibenclamide resided only in the α2‐selective‐(+)‐enantiomer; the imidazoline receptor‐selective‐(−)‐enantiomer was ineffective.

In vitro, (+)‐efaroxan increased the insulin secretory response to glibenclamide in rat freshly isolated and cultured islets of Langerhans, whereas (−)‐efaroxan was inactive. By contrast, (+)‐efaroxan did not potentiate glucose‐induced insulin secretion but (−)‐efaroxan induced a marked increase in insulin secretion from islets incubated in the presence of 6 mM glucose.

Incubation of rat islets under conditions designed to minimize the extent of α2‐adrenoceptor signalling (by receptor blockade with phenoxybenzamine; receptor down‐regulation or treatment with pertussis toxin) abolished the capacity of (+)‐and (±)‐efaroxan to enhance the insulin secretory response to glibenclamide. However, these manoeuvres did not alter the ability of (±)‐efaroxan to potentiate glucose‐induced insulin secretion.

The results indicate that the enantiomers of efaroxan exert differential effects on insulin secretion which may result from binding to effector sites having opposite stereoselectivity. Binding of (−)‐efaroxan (presumably to imidazoline receptors) results in potentiation of glucose‐induced insulin secretion, whereas interaction of (+)‐efaroxan with a second site leads to selective enhancement of sulphonylurea‐induced insulin release.

British Journal of Pharmacology (1997) 121, 799–805; doi:10.1038/sj.bjp.0701172
Effect of calpain inhibitor I, an inhibitor of the proteolysis of IκB, on the circulatory failure and multiple organ dysfunction caused by endotoxin in the rat
Authors: Ruetten Hartmut , Thiemermann Christoph
Published: August 2006

We compared the effects of calpain inhibitor I (inhibitor of the proteolysis of IκB and, hence, of the activation of nuclear factor κB (NFκB)) and dexamethasone on (i) the circulatory failure, (ii) multiple organ dysfunction and (iii) induction of the inducible isoforms of nitric oxide (NO) synthase (iNOS) and cyclo‐oxygenase (COX‐2) in anaesthetized rats with endotoxic shock.

Injection of lipopolysaccharide (LPS, E. coli, 10 mg kg−1, i.v.) resulted in hypotension and a reduction of the pressor responses elicited by noradrenaline. This circulatory dysfunction was attenuated by pretreatment of LPS‐rats with calpain inhibitor I (10 mg kg−1, i.v., 2 h before LPS) or dexamethasone (1 mg kg−1, i.v.).

Endotoxaemia also caused rises in the serum levels of (i) urea and creatinine (renal dysfunction), (ii) alanine aminotransferase (ALT), aspartate aminotransferase (AST) (hepatocellular injury), bilirubin and γ‐glutamyl transferase (γGT) (liver dysfunction), (iii) lipase (pancreatic injury) and (iv) lactate. Calpain inhibitor I and dexamethasone attenuated the liver injury, the pancreatic injury, the lactic acidosis as well as the hypoglycaemia caused by LPS. Dexamethasone, but not calpain inhibitor I, reduced the renal dysfunction caused by LPS.

Endotoxaemia for 6 h resulted in a substantial increase in iNOS and COX‐2 protein and activity in lung and liver, which was attenuated in LPS‐rats pretreated with calpain inhibitor I or dexamethasone.

Thus, calpain inhibitor I and dexamethasone attenuate (i) the circulatory failure, (ii) the multiple organ dysfunction (liver and pancreatic dysfunction/injury, lactic acidosis, hypoglycaemia), as well as (iii) the induction of iNOS and COX‐2 protein and activity in rats with endotoxic shock. We propose that prevention of the activation of NF‐κB in vivo may be useful in the therapy of circulatory shock or of disorders associated with local or systemic inflammation.

British Journal of Pharmacology (1997) 121, 695–704; doi:10.1038/sj.bjp.0701180
Interaction of a new bis‐indol derivative, KAR‐2 with tubulin and its antimitotic activity
Authors: Orosz Ferenc , Kovács János , Löw Péter , Vértessy Beáta G , Urbányi Zoltán , Ács Tibor , Keve Tibor , Ovádi Judit
Published: August 2006

KAR‐2 (3″‐(β‐chloroethyl)‐2″,4″‐dioxo‐3,5″‐spiro‐oxazolidino‐4‐deacetoxy‐vinblastine), is a bis‐indol derivative; catharantine is coupled with the vindoline moiety which contains a substituted oxazolidino group. Our binding studies showed that KAR‐2 exhibited high affinity for bovine purified brain tubulin (Kd=3 μM) and it inhibited microtubule assembly at a concentration of 10 nM.

Anti‐microtubular activity of KAR‐2 was highly dependent on the ultrastructure of microtubules: while the single tubules were sensitive, the tubules cross‐linked by phosphofructokinase (ATP: D‐fructose‐6‐phosphate‐1‐phosphotransferase, EC 2.7.1.11) exhibited significant resistance against KAR‐2.

The cytoplasmic microtubules of Chinese hamster ovary mammalian and Sf9 insect cells were damaged by 1 μg ml−1 KAR‐2, as observed by indirect immunofluorescence and transmission electron microscopy. Scanning electron microscopy revealed intensive surface blebbing on both types of cells in the presence of KAR‐2.

KAR‐2 was effective in the mouse leukaemia P338 test in vivo without significant toxicity. Studies on a primary cerebro‐cortical culture of rat brain and differentiated PC12 cells indicated that the toxicity of KAR‐2 was significantly lower than that of vinblastine. The additional property of KAR‐2 that distinguishes it from bis‐indol derivatives is the lack of anti‐calmodulin activity.
Evidence that antipsychotic drugs are inverse agonists at D2 dopamine receptors
Authors: Hall David A. , Strange Philip G.
Published: August 2006

The effects of a number of D2‐like dopamine receptor antagonists have been determined on forskolin‐stimulated cyclic AMP accumulation in Chinese hamster ovary (CHO) cells expressing the human D2short dopamine receptor (CHO‐D2S cells).

Dopamine inhibited the effect of forskolin (as expected for a D2 receptor). However, all of the antagonists tested, apart from UH232 and (−)‐butaclamol, were able to increase cyclic AMP accumulation above the forskolin control level. (+)‐Butaclamol elicited a similar stimulation of forskolin‐stimulated cyclic AMP accumulation in a CHO cell line expressing human D2long dopamine receptors whereas it exhibited no stimulating effect on forskolin‐stimulated cyclic AMP accumulation in untransfected CHO‐K1 cells.

There was a strong correlation between the EC50 values of these compounds for potentiation of cyclic AMP accumulation and their Ki values from radioligand binding experiments in CHO‐D2S cells.

The effects of both (+)‐butaclamol and dopamine in CHO‐D2S cells were inhibited by pre‐treatment with pertussis toxin indicating a role for Gi/Go proteins.

UH232 did not significantly affect forskolin‐stimulated cyclic AMP accumulation but this substance was able to inhibit the effects of both dopamine and (+)‐butaclamol in a concentration‐dependent manner. Thus the effects of (+)‐butaclamol on forskolin‐stimulated cyclic AMP accumulation are mediated directly via the D2 receptor rather than by reversal of the effects of an endogenous agonist.

These data suggest that the D2 dopamine receptor antagonists tested here, many of which are used clinically as antipsychotic drugs, are in fact inverse agonists at human D2 dopamine receptors.

British Journal of Pharmacology (1997) 121, 731–736; doi:10.1038/sj.bjp.0701196
Pharmacological characterization of the vanilloid receptor in the rat dorsal spinal cord
Authors: Wardle Kay A , Ranson Jennie , Sanger Gareth J
Published: August 2006

In the present study a novel 96‐well plate assay system was used to characterize pharmacologically the vanilloid receptor in the dorsal spinal cord of the rat. When activated, this receptor stimulates release of calcitonin gene‐related peptide (CGRP) from the central terminals of the afferent nerves.

Capsaicin, resiniferatoxin (RTX) and olvanil each evoked a concentration‐dependent increase in CGRP release with pEC50 values of 6.55±0.07, 7.90±0.24 and 6.19±0.15 respectively. RTX and olvanil were partial agonists with respect to capsaicin. All concentration‐effect curves were bell‐shaped.

The vanilloid receptor antagonist, capsazepine (10 μM) had no effect on basal peptide release but inhibited the CGRP release evoked by all 3 agonists to a similar extent. These results suggest that the antagonistic effects of capsazepine were agonist‐independent.

The capsaicin‐sensitive cation channel blocker, ruthenium red (10 μM) had no effect on basal CGRP release, but antagonized the peptide release evoked by capsaicin, olvanil and RTX.

The pharmacology of the vanilloid receptor in the rat dorsal spinal cord is not identical to that previously found in other systems. The reason for these differences is unclear, but the possibility of multiple classes of receptor cannot at this stage be ruled out.
Modulation of synovial blood flow by the calcitonin gene‐related peptide (CGRP) receptor antagonist, CGRP(8–37)
Authors: McMurdo Lorraine , Lockhart J C , Ferrell W R
Published: August 2006

The effect of the calcitonin gene‐related peptide (CGRP) receptor antagonist, CGRP(8–37) on blood flow in the knee joint of the anaesthetized rat was investigated.

Synovial blood flow in both exposed and intact, skin‐covered knees was measured by laser Doppler perfusion imaging.

Topical application of CGRP(8–37) caused a dose‐dependent fall in synovial blood flow in the exposed knee joint of the rat. At low (1.5nmol) doses of CGRP(8–37) there was no significant effect on synovial blood flow. In rats treated with 7.5nmol CGRP(8–37) there was a fall in synovial blood flow (maximum effect at 10min: −28.8±4.6%; n=7), which returned to resting levels within 30min. The highest dose (15nmol) of antagonist used in this study caused a marked (maximum at 10min: −35.6±9.3%; n=8), and prolonged (up to 30min) fall in blood flow.

Ten days after surgical denervation, CGRP(8–37) (15nmol, topical) had no significant effect on blood flow in the rat exposed knee joint (change in flux at 10min: −5.1±3.6%; n=4). This suggests that CGRP(8–37) acts selectively to antagonize the actions of a neurally derived product, probably CGRP, on the rat synovial vasculature.

In skin‐covered knee joints, intra‐articular injection of CGRP(8–37) (15nmol; bolus) elicited a significant fall in synovial blood flow (maximum effect at 10min: −15.5±5.8%; n=6).

CGRP (0.01, 0.1 or 1.0nmol; topical) caused a dose‐dependent increase in exposed knee joint blood flow, which was attenuated by co‐administration of 1.5nmol CGRP(8–37). For example, 1nmol CGRP elicited a peak increase in flux at 10min of 94.7±31.8% (n=8) and 28.8±8.9% (n=7) in the absence and presence of CGRP(8–37), respectively. The vasodilator responses induced by acetylcholine (ACh) (10nmol, topical; n=4–5) or sodium nitroprusside (SNP) (10nmol, topical; n=4–5) were unaltered in the presence of CGRP(8–37) (1.5nmol, topical).

Thus, the CGRP receptor antagonist CGRP(8–37) elicits vasoconstriction in the rat synovium. This suggests that the endogenous, basal release of CGRP may play a physiological role in the regulation of blood flow in the rat knee joint.
Inhibition of muscarinic K+ current in guinea‐pig atrial myocytes by PD 81,723, an allosteric enhancer of adenosine binding to A1 receptors
Authors: Brandts B , Bünemann M , Hluchy J , Sabin G V , Pott L
Published: August 2006

PD 81,723 has been shown to enhance binding of adenosine to A1 receptors by stabilizing G protein‐receptor coupling (‘allosteric enhancement’). Evidence has been provided that in the perfused hearts and isolated atria PD 81,723 causes a sensitization to adenosine via this mechanism.

We have studied the effect of PD 81,723 in guinea‐pig isolated atrial myocytes by use of whole‐cell measurement of the muscarinic K+ current (IK(ACh)) activated by different Gi‐coupled receptors (A1, M2, sphingolipid). PD 81,273 caused inhibition of IK(ACh) (IC50≃5μm) activated by either of the three receptors. Receptor‐independent IK(ACh) in cells loaded with GTP‐γ‐S and background IK(ACh), which contributes to the resting conductance of atrial myocytes, were equally sensitive to PD 81,723. At no combination of concentrations of adenosine and PD 81,723 could an enhancing effect be detected.

The compound was active from the outside only. Loading of the cells with PD 81,723 (50μm) via the patch pipette did not affect either IK(ACh) or its sensitivity to adenosine. We suggest that PD 81,723 acts as an inhibitor of inward rectifying K+ channels; this is supported by the finding that ventricular IK1, which shares a large degree of homology with the proteins (GIRK1/GIRK4) forming IK(ACh) but is not G protein‐gated, was also blocked by this compound.

It is concluded that the functional effects of PD 81,723 described in the literature are not mediated by the A1 adenosine receptor‐Gi‐IK(ACh) pathway.
Regulation of bradykinin B2‐receptor expression by oestrogen
Authors: Madeddu Paolo , Emanueli Costanza , Varoni Maria Vittoria , Demontis Maria Piera , Anania Vittorio , Gorioso Nicola , Chao Julie
Published: August 2006

Tissue kallikrein is overexpressed in the kidney of female rats, this sexual dimorphism being associated with a greater effect of early blockade of bradykinin B2‐receptors on female blood pressure phenotype. We evaluated the effect of ovariectomy and oestradiol benzoate (50 μg kg−1 every two days for two weeks) on the vasodepressor response to intra‐arterial injection of bradykinin (150–900 ng kg−1) and on the expression of bradykinin B2‐receptors.

Ovariectomy reduced the magnitude of the vasodepressor response to bradykinin and unmasked a secondary vasopressor effect. Oestrogen replacement restored the vasodepressor response to bradykinin in ovariectomized rats.

The vasodepressor responses to sodium nitroprusside (3–18 μg kg−1), acetylcholine (30–600 ng kg−1), desArg9‐bradykinin (150–900 ng kg−1) or prostaglandin E2 (30–600 ng kg−1) were significantly reduced by ovariectomy. Oestrogen restored to normal the responses to desArg9‐bradykinin, acetylcholine and prostaglandin E2, but not that to sodium nitroprusside.

B2‐receptor mRNA levels were decreased by ovariectomy in the aorta and kidney and they were restored to normal levels by oestrogen. Neither ovariectomy nor oestradiol affected receptor expression in the heart and uterus.

These results indicate that oestrogen regulates B2‐receptor gene expression and function. Since kinins exert a cardiovascular protective action, reduction in their vasodilator activity after menopause might contribute to the increased risk of pathological cardiovascular events. Conversely, the cardioprotective effects of oestrogen replacement might be, at least in part, mediated by activation of the kallikrein‐kinin system.

British Journal of Pharmacology (1997) 121, 1763–1769; doi:10.1038/sj.bjp.0701255
Effects of captopril, losartan, and nifedipine on cell hypertrophy of cultured vascular smooth muscle from hypertensive Ren‐2 transgenic rats
Authors: Peiró Concepción , Llergo José L , Angulo Javier , López‐Novoa José M , Rodríguez‐López Ana , Rodríguez‐Mañas Leocadio , Sánchez‐Ferrer Carlos F
Published: August 2006

We hypothesized that tissular renin‐angotensin system (RAS) induces vascular hypertrophy in hypertensive Ren‐2 transgenic rats (TGR; strain name TGR(mRen2)L27). This assumption was tested in cell cultures of vascular smooth muscle (VSMC) from both hypertensive TGR and control normotensive Sprague‐Dawley (SD) rats. Planar cell surface area, protein synthesis, and protein content per cell were studied, the role for locally produced angiotensin II (AII) was evaluated and the possible pharmacological interference by different drugs was analysed.

By use of radioimmunoassay techniques, AII could be determined in TGR cultures (10.25±0.12 pg per 107 cells) while it could not be detected in SD ones.

Under serum‐free conditions, VSMC from hypertensive TGR were hypertrophic when compared to SD VSMC, as they presented a higher protein content per cell (335±18 and 288±7 pg per cell respectively; P<0.05) and increased mean planar cell surface area, as determined by image analysis (4,074±238 and 4,764±204 μm2, respectively; P<0.05).

When exogenously added to cultured SD and TGR VSMC, AII (100 pM to 1 μM) promoted protein synthesis and protein content in a concentration‐dependent manner without affecting DNA synthesis. Maximal effects were observed at 100 nM. At this concentration, AII effectively increased planar cell surface area in both SD and TGR cultures by ∼20%.

Treatment of TGR cultures, in the absence of exogenous AII, with the angiotensin‐converting enzyme inhibitor captopril or the angiotensin AT1 receptors antagonist losartan (100 nM to 10 μM) reduced planar cell surface area in a concentration‐dependent manner. In addition, both captopril and losartan (10 μM), decreased protein synthesis by ∼15%.

Treatment of SD VSMC, in the absence of exogenous AII, with both captopril and losartan had no effect either on planar cell surface area or protein synthesis.

Treatment with the Ca2+ antagonist nifedipine (100 nM to 10 μM) reduced cell size in both SD and TGR cultures. Maximal cell reduction reached by nifedipine averaged 906±58 and 1,292±57 μm2, in SD and TGR, respectively (P<0.05). In addition, nifedipine, nitrendipine and nisoldipine (all at 10 μM) decreased protein synthesis in both cell types by 15–25%.

We concluded that cultured VSMC from TGR are hypertrophic in comparison with those from SD. This cell hypertrophy can be the consequence of the expression of the transgene Ren‐2 that activates a tissular RAS and locally produces AII, which acts in a paracrine, autocrine, or intracrine manner. Cell hypertrophy in TGR cultures could be selectively reduced by RAS blockade, while nifedipine decreased cell size and protein synthesis in both hypertrophic and non hypertrophic cells.
Characterization of P2 receptors for purine and pyrimidine nucleotides in human placental cotyledons
Authors: Ralevic Vera , Burrell Stephen , Kingdom John , Burnstock Geoffrey
Published: August 2006

The aim of this study was to characterize P2 receptors in the arterial vascular bed of human perfused placental cotyledons. Vasoconstrictor responses to bolus injections of purine and pyrimidine nucleotides were tested at basal tone, and vasodilator responses in preparations with tone raised by perfusion with prostaglandin F2α (PGF2α; 10–50nm).

At basal tone, bolus injections of the P2X‐selective agonist α,β‐methylene ATP (α,β‐meATP; 0.5–500nmol) elicited dose‐dependent vasoconstriction. ATP (0.005–5μmol) also elicited dose‐dependent vasoconstriction, but was less potent than α,β‐meATP. Vasoconstriction was also elicited by other nucleotides, but only at the highest dose tested (5μmol): UTP >CTP=ITP (n=6). GTP and TTP did not cause vasoconstriction.

Constrictor responses to bolus injections of α,β‐meATP were resistant to desensitization and were not significantly affected when carried out in the presence of 1μm α,β‐meATP added to the perfusate. However, responses to bolus injections of α,β‐meATP were partially blocked by perfusion with 10μm α,β‐meATP. In contrast, responses to ATP and UTP were unaffected by 10μm α,β‐meATP. The P2X receptor antagonist pyridoxalphosphate‐6‐azophenyl‐2′,4′‐disulphonic acid (PPADS; 10 and 100μm) had no significant effect on vasoconstriction mediated by α,β‐meATP and ATP.

Removal of the endothelium had no significant effect on constrictor responses to α,β‐meATP, ATP and UTP. Inhibition of nitric oxide (NO) synthesis with NG‐nitro‐l‐arginine methyl ester (l‐NAME; 100μm) had no significant effect on vasoconstriction to ATP and α,β‐meATP.

In preparations with tone raised with PGF2α (10–50nm) vasodilatation was elicited by nucleotides with the following order of potency: 2MeSATP=ADP >>ATP >UTP >CTP=GTP=ITP=TTP. pD2 values were: 2MeSATP, 10.03±0.26 (n=7); ADP, 9.97±0.40 (n=5); ATP, 8.89±0.18 (n=7); UTP, 7.79±0.35 (n=7). Maximal responses to 2MeSATP and ADP were similar and were approximately 40% greater than maximal responses to ATP and UTP.

Vasodilator responses to nucleotides were abolished by l‐NAME (100μm) and by removal of the endothelium.

In conclusion, contractile responses mediated by α,β‐meATP and ATP in human placental smooth muscle are resistant to desensitization and insensitive to PPADS and, thus, show a dissimilar pharmacological profile to the classic smooth muscle P2X1 receptor. There may be two subtypes of smooth muscle P2 receptor based on differential antagonism of α,β‐meATP and ATP with α,β‐meATP. A smooth muscle P2 receptor mediates vasoconstriction to UTP, and may indicate a further subtype. Endothelium‐dependent, NO‐dependent, vasodilatation to 2MeSATP and ADP may be mediated by P2Y1 receptors, while endothelial P2Y2 receptors are likely to mediate NO‐dependent relaxation to ATP and UTP.
Inhibition by heterologously‐expressed P2Y2 nucleotide receptors of N‐type calcium currents in rat sympathetic neurones
Authors: Filippov A K , Webb T E , Barnard E A , Brown D A
Published: August 2006

The P2Y2 nucleotide receptor has previously been shown to stimulate phosphoinositide breakdown. We now show that, when P2Y2 receptors are heterologously expressed by cRNA injection into dissociated rat sympathetic neurones, activation of these receptors by uridine 5′‐triphosphate (UTP) or adenosine 5′‐triphosphate (ATP) inhibits the N‐type voltage‐gated calcium current by ∼65%, with an IC50 of 0.5 μM. Thus, the same molecular species of nucleotide receptor can link to two different effector pathways.
Effects of β2‐agonist‐ and dexamethasone‐treatment on relaxation and regulation of β‐adrenoceptors in human bronchi and lung tissue
Authors: Hauck R. W. , Harth M , Schulz C , Präuer H , Böhm M , Schömig A
Published: August 2006

Long‐term treatment with β2‐adrenoceptor agonists can lead to a decreased therapeutic efficacy of bronchodilatation in patients with obstructive pulmonary disease. In order to examine whether or not this is due to β‐adrenoceptor desensitization, human bronchial muscle relaxation was studied in isolated bronchial rings after pretreatment with β2‐adrenoceptor agonists. Additionally, the influence of pretreatment with dexamethasone on desensitization was studied.

The effect of β2‐agonist incubation alone and after coincubation with dexamethasone on density and affinity of β‐adrenoceptors was investigated by radioligand binding experiments.

In human isolated bronchi, isoprenaline induces a time‐ and concentration‐dependent β‐adrenoceptor desensitization as judged from maximal reduction in potency by a factor of 7 and reduction of 73±4% in efficacy of isoprenaline to relax human bronchial smooth muscle.

After an incubation period of 60 min with 100 μmol l−1 terbutaline, a significant decline in its relaxing efficacy (81±8%) and potency (by a factor 5.5) occurred.

Incubation with 30 μmol l−1 isoprenaline for 60 min did not impair the maximal effect of a subsequent aminophylline response but led to an increase in potency (factor 4.4).

Coincubation of dexamethasone with isoprenaline (120 min; 30 μmol l−1) preserved the effect of isoprenaline on relaxation (129±15%).

In radioligand binding experiments, pretreatment of lung tissue for 60 min with isoprenaline (30 μmol l−1) resulted in a decrease in β‐adrenoceptor binding sites (Bmax) to 64±1.6% (P<0.05), while the antagonist affinity (KD) for [3H]‐CGP‐12177 remained unchanged.

In contrast, radioligand binding studies on lung tissue pretreated with either dexamethasone (30 μmol l−1) or isoprenaline (30 μmol l−1) plus dexamethasone (30 μmol l−1) for 120 min did not lead to a significant change of Bmax (160±22.1% vs 142.3±28.7%) or KD (5.0 nmol l−1 vs 3.5 nmol l−1) compared to the controls.

In conclusion, pretreatment of human bronchi with β‐adrenoceptor agonists leads to functional desensitization and, in lung tissue, to down‐regulation of β‐adrenoceptors. This effect can be counteracted by additional administration of dexamethasone. Our model of desensitization has proved useful for the identification of mechanisms of β‐adrenoceptor desensitization and could be relevant for the evaluation of therapeutic strategies to counteract undesirable effects of long‐term β‐adrenoceptor stimulation.

British Journal of Pharmacology (1997) 121, 1523–1530; doi:10.1038/sj.bjp.0701289
Nonlinear propagation of ultraintense and ultrashort laser pulses in a plasma channel limited by metallic walls
Authors: Sid A. , Debbache D. , Bendib A.
Published: August 2006

The nonlinear propagation of an ultraintense and ultrashort (UIUS) laser pulse in a metallic capillary is investigated using a classical model which takes into account the inverse bremsstrahlung absorption (IBA) in the formed plasma. The attenuation of the laser pulse due to the IBA in the plasma and to the laser energy dissipation in the metallic walls is shown. The guiding length and the twist of the laser pulse temporal envelope are presented for several values of the parameters of the plasma, the laser pulse and the metal. The numerical treatment shows that the guiding length increases when the pulse duration becomes shorter. This calculus shows also that in the case of moderate electronic densities, ne<1017m−3, the formed plasma has a negligible effect compared to that of the metallic walls.
Evaluation representations of quantum affine algebras at roots of unity
Authors: Abe Yuuki , Nakashima Toshiki
Published: August 2006

The purpose of this paper is to compute the Drinfel’d polynomials for two types of evaluation representations of quantum affine algebras at roots of unity and construct those representations as the submodules of evaluation Schnizer modules. Moreover, we obtain the necessary and sufficient condition for that the two types of evaluation representations are isomorphic to each other.
Frustration and hydrophobicity interplay in protein folding and protein evolution
Authors: Oliveira Leandro C. , Silva Ricardo T. H. , Leite Vitor B. P. , Chahine Jorge
Published: August 2006

A lattice model is used to study mutations and compacting effects on protein folding rates and folding temperature. In the context of protein evolution, we address the question regarding the best scenario for a polypeptide chain to fold: either a fast nonspecific collapse followed by a slow rearrangement to form the native structure or a specific collapse from the unfolded state with the simultaneous formation of the native state. This question is investigated for optimized sequences, whose native state has no frustrated contacts between monomers, and also for mutated sequences, whose native state has some degree of frustration. It is found that the best scenario for folding may depend on the amount of frustration of the native structure. The implication of this result on protein evolution is discussed.
An adiabatic invariant for single-particle motion in static axisymmetric magnetic fields with large wave-number variations
Authors: Keyes Jonathan , Weitzner Harold
Published: August 2006

Single-particle motion is considered in a static, axisymmetric field in which the magnitudes of the toroidal and poloidal fields vary on a distance scale comparable with the Larmor radius. It is assumed, however, that the distance scale defined by the magnetic surfaces is large compared with the Larmor radius. Expressions for the magnetic moment are given for points in the phase plane near the critical points.