bluuebunny/crossref_metadata_2025 huggingface dataset:
KMUP‐1 relaxes rabbit corpus cavernosum smooth muscle in vitro and in vivo: involvement of cyclic GMP and K+ channels
Authors: Lin Rong‐Jyh , Wu Bin‐Nan , Lo Yi‐Ching , Shen Kuo‐Pyng , Lin Young‐Tso , Huang Chun‐Hsiung , Chen Ing‐Jun
Published: January 2005

In isolated endothelium‐intact or denuded rabbit corpus cavernosum preconstricted with phenylephrine, KMUP‐1 (0.001 – 10 μM) caused a concentration‐dependent relaxation.

This relaxation of KMUP‐1 was attenuated by endothelium removed, high K+ and pretreatments with a soluble guanylyl cyclase (sGC) inhibitor ODQ (1 μM), a NOS inhibitor L‐NAME (100 μM), a K+ channel blocker TEA (10 mM), a KATP channel blocker glibenclamide (1 μM), a voltage‐dependent K+ channel blocker 4‐AP (100 μM) and Ca2+‐dependent K+ channel blockers apamin (1 μM) and charybdotoxin (ChTX, 0.1 μM).

The relaxant responses of KMUP‐1 (0.01, 0.05, 0.1 μM) together with a PDE inhibitor IBMX (0.5 μM) had additive actions on rabbit corpus cavernosum smooth muscle (CCSM).

KMUP‐1 (0.01 – 10 μM) induced increase of intracellular cyclic GMP level in the primary cell culture of rabbit CCSM. This increase in cyclic GMP content was abolished in the presence of ODQ (10 μM).

Both KMUP‐1 and sildenafil at 0.2, 0.4, 0.6 mg kg−1 caused increases of intracavernous pressure (ICP) and duration of tumescene (DT) in a dose‐dependent manner. These in vivo activities of ICP for sildenafil and KMUP‐1 are consistent with those of in vitro effects of cyclic GMP.

KMUP‐1 has the following merits: (1) inhibition of PDE or cyclic GMP breakdown, (2) stimulation of NO/sGC/cyclic GMP pathway, and (3) subsequent stimulation of K+ channels, in rabbit CCSM. We suggest that these merits play prominent roles in KMUP‐1‐induced CCSM relaxation‐associated increases of ICP and penile erection.

British Journal of Pharmacology (2002) 135, 1159–1166; doi:10.1038/sj.bjp.0704554
Permeability of porcine blood brain barrier to somatostatin analogues
Authors: Fricker Gert , Nobmann Stephanie , Miller David S
Published: January 2005

Transport of a fluorescent somatostatin analogue (NBD‐octreotide) across freshly isolated functionally intact capillaries from porcine brain was visualized by confocal microscopy and quantitated by image analysis.

Luminal accumulation of NBD‐octreotide showed all characteristics of specific and energy‐dependent transport. Steady‐state luminal fluorescence averaged 2 – 3 times cellular fluorescence and was reduced to cellular levels when metabolism was inhibited by NaCN.

The accumulation of NBD‐octreotide in capillary lumens was inhibited in a concentration‐dependent manner by unlabelled octreotide, by verapamil, PSC‐833 and cyclosporin A, potent inhibitors of p‐glycoprotein, and by leucotriene C4, a strong modulator of Mrp2. Conversely, unlabelled octreotide reduced luminal accumulation of fluorescent BODIPY‐verapamil on p‐glycoprotein and of fluorescein‐methotrexate, on Mrp2. None of the inhibitors used significantly reduced cellular accumulation of the fluorescent substrates.

Together, the data are consistent with octreotide being transported across the luminal membrane of porcine brain capillaries by both P‐gp and Mrp2, providing further evidence that both transporters contribute substantially to the active barrier function of this endothelium.

British Journal of Pharmacology (2002) 135, 1308–1314; doi:10.1038/sj.bjp.0704557
The flavonol quercetin activates basolateral K+ channels in rat distal colon epithelium
Authors: Cermak Rainer , Kuhn Gisela , Wolffram Siegfried
Published: January 2005

The flavonol quercetin has been shown to activate a Cl− secretion in rat colon. Unlike the secretory activity of the related isoflavone genistein, quercetin's secretory activity does not depend on cyclic AMP; instead, it depends on Ca2+. We investigated the possible involvement of Ca2+ dependent basolateral K+ channels using apically permeabilized rat distal colon epithelium mounted in Ussing chambers.

In intact epithelium, quercetin induced an increase in short‐circuit current (Isc), which was diminished by the Cl− channel blockers NPPB and DPC, but not by glibenclamide, DIDS or anthracene‐9‐carboxylic acid. The effect of the flavonol was also inhibited by several serosally applied K+ channel blockers (Ba2+, quinine, clotrimazole, tetrapentylammonium, 293B), whereas other K+ channel blockers failed to influence the quercetin‐induced increase in Isc (tetraethylammonium, charybdotoxin).

The apical membrane was permeabilized by mucosal addition of nystatin and a serosally directed K+ gradient was applied. The successful permeabilization was confirmed by experiments demonstrating the failure of bumetanide to inhibit the carbachol‐induced current.

In apically permeabilized epithelium, quercetin induced a K+ current (IK), which was neither influenced by ouabain nor by bumetanide. Whereas DPC, NPPB, charybdotoxin and 293B failed to inhibit this IK, quinine, Ba2+, clotrimazole and tetrapentylammonium were effective blockers of this current.

We conclude from these results that at least part of the quercetin‐induced Cl− secretion can be explained by an activation of basolateral K+ channels.

British Journal of Pharmacology (2002) 135, 1183–1190; doi:10.1038/sj.bjp.0704564
Modulation of contraction by α2A/D‐adrenoceptors in mouse aorta: evidence employing knockout technology
Authors: Vandeputte Catherine , Docherty James R
Published: January 2005

We have investigated noradrenaline‐evoked contractions in endothelium‐denuded aorta from wild‐type and α2A/D‐adrenoceptor knockout mice. The maximum contraction to noradrenaline was significantly larger (1.36±0.24 mN, n=5) in aorta from knockout than from wild‐type animals (0.78±0.14 mN, n=12, P<0.05), but there was no difference in potency of noradrenaline. There was no difference between groups in the contraction to KCl (80 mM) or PGF2α (10 μM).

The contraction to noradrenaline (10 μM) was significantly larger in aorta from knockout animals, but yohimbine (1 μM) significantly increased this contraction (to 136±10% of control, n=6) in aorta from wild‐type but not from knockout (97±10%, n=6, P<0.05).

In tissues precontracted with PGF2α (10 μM), xylazine (1 μM) produced relaxations only in tissues from wild‐type mice.

The K+ channel blocker glibenclamide (1 μM) had no significant effects on contractions to noradrenaline in either group.

It is concluded that an α2A/D‐adrenoceptor exerts an inhibitory modulation of contraction in mouse aorta.

British Journal of Pharmacology (2002) 135, 1209–1212; doi:10.1038/sj.bjp.0704567
Proteinase‐activated receptor‐1 agonists attenuate nociception in response to noxious stimuli
Authors: Asfaha Samuel , Brussee Valentine , Chapman Kevin , Zochodne Douglas W , Vergnolle Nathalie
Published: January 2005

Proteinase‐activated receptor‐1 (PAR‐1) is activated by thrombin and can be selectively activated by synthetic peptides (PAR‐1‐activating peptide: PAR‐1‐AP) corresponding to the receptor's tethered ligand. PAR‐1 being expressed by afferent neurons, we investigated the effects of PAR‐1 agonists on nociceptive responses to mechanical and thermal noxious stimuli. Intraplantar injection of selective PAR‐1‐AP increased nociceptive threshold and withdrawal latency, leading to mechanical and thermal analgesia, while control peptide had no effect. Intraplantar injection of thrombin also showed analgesic properties in response to mechanical, but not to thermal stimulus. Co‐injection of PAR‐1‐AP with carrageenan significantly reduced carrageenan‐induced mechanical and thermal hyperalgesia, while thrombin reduced carrageenan‐induced mechanical but not thermal hyperalgesia. The fact that thrombin is not a selective agonist for PAR‐1 may explain the different effects of thrombin and PAR‐1‐AP. These results identified analgesic properties for selective PAR‐1 agonists that can modulate nociceptive response to noxious stimuli in normal and inflammatory conditions.

British Journal of Pharmacology (2002) 135, 1101–1106; doi:10.1038/sj.bjp.0704568
E‐p‐Methoxycinnamic acid protects cultured neuronal cells against neurotoxicity induced by glutamate
Authors: Kim So Ra , Sung Sang Hyun , Jang Young Pyo , Markelonis George J , Oh Tae H , Kim Young Choong
Published: January 2005

We previously reported that four new phenylpropanoid glycosides and six known cinnamate derivatives isolated from roots of Scrophularia buergeriana Miquel (Scrophulariaceae) protected cultured cortical neurons from neurotoxicity induced by glutamate. Here, we have investigated the structure‐activity relationships in the phenylpropanoids using our primary culture system.

The α,β‐unsaturated ester moiety and the para‐methoxy group in the phenylpropanoids appeared to play a vital role in neuroprotective activity. This suggested that E‐p‐methoxycinnamic acid (E‐p‐MCA) might be a crucial component for their neuroprotective activity within the phenylpropanoid compounds. E‐p‐MCA significantly attenuated glutamate‐induced neurotoxicity when added prior to an excitotoxic glutamate challenge.

The neuroprotective activity of E‐p‐MCA appeared to be more effective in protecting neurons against neurotoxicity induced by NMDA than from that induced by kainic acid. E‐p‐MCA inhibited the binding of [propyl‐2,3‐3H]‐CGP39653 and [2‐3H]‐glycine to their respective binding sites on rat cortical membranes. However, even high concentrations of E‐p‐MCA failed to inhibit completely [propyl‐2,3‐3H]‐CGP39653 and [2‐3H]‐glycine binding.

Indeed, E‐p‐MCA diminished the calcium influx that routinely accompanies glutamate‐induced neurotoxicity, and inhibited the subsequent overproduction of nitric oxide and cellular peroxide in glutamate‐injured neurons.

Thus, our results suggest that E‐p‐MCA exerts significant protective effects against neurodegeneration induced by glutamate in primary cultures of cortical neurons by an action suggestive of partial glutamatergic antagonism.

British Journal of Pharmacology (2002) 135, 1281–1291; doi:10.1038/sj.bjp.0704576
Algogen‐specific pain processing in mouse spinal cord: differential involvement of voltage‐dependent Ca2+ channels in synaptic transmission
Authors: Kato Akemi , Ohkubo Tsuyako , Kitamura Kenji
Published: January 2005

The effects of intrathecal (i.t.) administration of N‐, P/Q‐ or L‐type voltage‐dependent Ca2+‐channel blockers were tested in two pain models involving bradykinin (BK)‐ and α,β‐methylene ATP (α,βmeATP)‐induced activation of primary afferent neurons in mice.

The nociceptive response (amount of time spent licking and biting the hindpaw) induced by intraplantar injection of BK (500 pmol mouse−1) was significantly attenuated by both ω‐conotoxin GVIA (N‐type blocker) and calciseptine (L‐type) but not by ω‐agatoxin IVA (P/Q‐type).

The nociceptive response induced in a similar way by α,βmeATP (100 nmol) was significantly inhibited by both the above N‐ and P/Q‐type Ca2+‐channel blockers but not by the L‐type blocker.

The nociceptive responses elicited by BK and α,βmeATP were dose‐dependently inhibited by a tachykinin‐NK1‐receptor antagonist (L‐703,606) and an N‐methyl‐D‐aspartate (NMDA)‐receptor antagonist (D‐AP5), respectively.

Intrathecal administration of substance P (SP) (1.8 nmol) or NMDA (350 pmol) elicited algesic responses, such as licking, biting and scratching of the hindquarters. The SP‐induced algesic behaviour was significantly inhibited by the L‐type blocker but not by the N‐type. The NMDA‐induced response was not affected by either the N‐ or the P/Q‐type blocker.

These findings suggest that BK and ATP most likely excite different types of sensory neurons in the periphery and that within the spinal cord the former stimulates peptidergic transmission regulated by presynaptic N‐ and postsynaptic L‐type Ca2+ channels, while the latter stimulates glutamatergic transmission regulated by presynaptic N‐ and P/Q‐type channels.

British Journal of Pharmacology (2002) 135, 1336–1342; doi:10.1038/sj.bjp.0704578
Allergenic sensitization prevents upregulation of haemopoiesis by cyclo‐oxygenase inhibitors in mice
Authors: Lintomen Letícia , Gaspar Elsas Maria Ignez C , Maximiano Elisabeth Santos , Affonso de Paula Neto Heitor , Joseph Danielle , Vargaftig B Boris , Xavier Elsas P
Published: January 2005

We evaluated whether immunization affects bone‐marrow responses to indomethacin, because allergenic sensitization and challenge upregulate responses to haemopoietic cytokines (including IL‐5‐driven eosinopoiesis) in murine bone‐marrow, while indomethacin upregulates haemopoiesis and protects bone‐marrow from radiation damage.

Progenitor (semi‐solid) and/or precursor (liquid) cultures were established from bone‐marrow of: (a) normal mice; (b) ovalbumin‐sensitized mice, with or without intranasal challenge. Cultures were established with GM‐CSF (2 ng ml−1) or IL‐5 (1 ng ml−1), respectively, alone or associated with indomethacin (10−7 – 10−11 M) or aspirin (10−7 – 10−8 M). Total myeloid colony numbers and numbers of eosinophil‐peroxidase‐positive cells were determined at day 7.

In naïve BALB/c mice, indomethacin (10−7 – 10−9 M) increased GM‐CSF‐stimulated myeloid colony formation (P=0.003 and P=0.009, respectively). In contrast, it had no effect on bone‐marrow of ovalbumin‐sensitized and challenged mice. Indomethacin (10−7 – 10−9 M) also increased eosinophil precursor responses to IL‐5 in bone‐marrow of naïve (P<0.001 and P=0.002 respectively), but not sensitized‐challenged mice. Aspirin (10−7 M) had similar effects, equally abolished by sensitization. Enhancement of haemopoiesis by indomethacin required adherent cells from naïve bone‐marrow. Nonadherent cells responded to IL‐5 but not to indomethacin. Indomethacin was effective on bone‐marrow from sham‐sensitized, ovalbumin‐challenged, but not from sensitized, saline‐challenged mice. Plasma transfer from immune mice abolished eosinophil precursor responses to indomethacin in bone‐marrow of naïve recipients. This was not prevented by previous removal of antibody from immune plasma.

COX inhibitors enhance haemopoiesis in naïve but not allergic mice. Responsiveness to indomethacin can be abolished either by active sensitization or by immune plasma transfer. Specific antibody is not involved.

British Journal of Pharmacology (2002) 135, 1315–1323; doi:10.1038/sj.bjp.0704580
Characterization of pre‐ and postsynaptic muscarinic receptors in circular muscle of pig gastric fundus
Authors: Leclere Pascal G , Lefebvre Romain A
Published: January 2005

This study investigated the subtype of muscarinic receptors on the cholinergic neurones and smooth muscle in the circular muscle of the pig gastric fundus.

Muscarinic antagonists, except MT‐3, concentration‐dependently inhibited the contractions induced by a given concentration of acetylcholine. Concentration‐response curves by acetylcholine were shifted rightwards in a parallel manner without depression of the maximum by the muscarinic antagonists, except by MT‐3 that induced a leftward shift. Correlation of the pIC50 and pA2 values with published pKi values for the five muscarinic receptor subtypes suggests that the muscarinic receptors on pig gastric fundus circular muscle belong to the M3 subtype.

Electrically‐evoked contractions (40 V, 4 Hz, 0.25 ms, 2 min) were concentration‐dependently inhibited by the muscarinic antagonists except for methoctramine and AF‐DX 116, that increased the amplitude of the electrically‐induced contractions in lower concentrations. MT‐3 tended to increase the electrically‐induced contractions.

The antagonists, except MT‐3, concentration‐dependently increased the electrically‐induced tritium outflow (40 V, 4 Hz, 0.25 ms, 2 min) after incubation of the tissues with [3H]‐choline. MT‐3 (3×10−8 and 10−7 M) decreased the electrically‐induced tritium release. Correlation of the pIC50 values with published pKi values for the different muscarinic receptor subtypes yielded a significant and comparable correlation for M1, M3, M4 and M5 receptors.

These results suggest that the postsynaptic receptors in circular muscle of the pig gastric fundus belong to the M3 subtype. However, the presynaptic receptor could not be clearly defined, although it does certainly not belong to the M2 subtype.

British Journal of Pharmacology (2002) 135, 1245–1254; doi:10.1038/sj.bjp.0704582
Inhibition of cyclo‐oxygenase‐2 exacerbates ischaemia‐induced acute myocardial dysfunction in the rabbit
Authors: Rossoni Giuseppe , Muscara Marcelo N , Cirino Giuseppe , Wallace John L
Published: January 2005

The effects of treatment with a number of cyclo‐oxygenase inhibitors, (celecoxib, meloxicam, DuP‐697 and aspirin) on ischaemia‐reperfusion‐induced myocardial dysfunction were examined using an in vitro perfused rabbit heart model.

Ischaemia resulted in myocardial dysfunction, as indicated by a significant increase in left ventricular end diastolic pressure and marked changes in coronary perfusion pressure and left ventricular developed pressure. In the post‐ischaemic state, coronary perfusion pressure increased dramatically, left ventricular developed pressure recovered to a small degree and there were significant increases in creatinine kinase release (indicative of myocardial damage) and prostacyclin release.

Pretreatment with aspirin, or with drugs that selectively inhibit cyclo‐oxygenase‐2 (celecoxib, meloxicam and DuP‐697), resulted in a concentration‐dependent exacerbation of the myocardial dysfunction and damage. Exacerbation of myocardial dysfunction and damage was evident with 10 μM concentrations of the cyclo‐oxygenase‐2 inhibitors, which inhibited prostacyclin release but did not affect cyclo‐oxygenase‐1 activity (as measured by whole blood thromboxane synthesis).

NCX‐4016, a nitric oxide‐releasing aspirin derivative, significantly reduced the myocardial dysfunction and damage caused by ischaemia and reperfusion. Beneficial effects were observed even at a concentration (100 μM) that significantly inhibited prostacyclin synthesis by the heart.

The results suggest that prostacyclin released by cardiac tissue in response to ischaemia and reperfusion is derived, at least in part, from cyclo‐oxygenase‐2. Cyclo‐oxygenase‐2 plays an important protective role in a setting of ischaemia‐reperfusion of the heart.

British Journal of Pharmacology (2002) 135, 1540–1546.; doi:10.1038/sj.bjp.0704585
Tonic activity of the rat adipocyte A1‐adenosine receptor
Authors: Liang Hui‐Xiu , Belardinelli Luiz , Ozeck Mark J , Shryock John C
Published: January 2005

Adipocyte A1‐adenosine receptors (A1 AdoR) tonically inhibit adenylyl cyclase and lipolysis. Three potential explanations for tonic activity of A1AdoR of rat epididymal adipocytes were investigated: high affinity of adenosine for the receptor, efficient coupling of receptor activation to response, and spontaneous activity of the receptor in the absence of agonist.

The affinity of adenosine for the adipocyte A1AdoR was determined as 4.6 μM by analysis of effects of an irreversible receptor antagonist on agonist concentration‐response relationships. In contrast, the potency of adenosine to decrease cyclic AMP in isolated adipocytes was 1.4 nM.

Occupancy by agonist of the A1AdoR was efficiently coupled to functional response (decrease of adipocyte cyclic AMP content). Activation by adenosine of less than 1% of A1AdoRs caused a near‐maximal decrease of cyclic AMP in adipocytes. Thus the receptor reserve for adenosine to decrease cyclic AMP content of adipocytes was greater than 99%.

Affinities and receptor reserves for other A1AdoR agonists were determined. Agonists appeared to differ more in their affinity for the receptor than in their intrinsic efficacy to activate it.

A1AdoRs were inactive in the absence of agonist.

It is concluded that adipocyte A1AdoR are tonically activated by endogenous adenosine at nanomolar concentrations. The expression of a high density of A1AdoR that are efficiently coupled to a functional response enables the adipocyte to respond with high sensitivity to the low‐affinity agonist, adenosine. Adipocytes may be a model for cells whose functions are tonically modulated by adenosine present in the interstitium of well‐oxygenated tissues.

British Journal of Pharmacology (2002) 135, 1457–1466; doi:10.1038/sj.bjp.0704586
The human 5‐HT7 serotonin receptor splice variants: constitutive activity and inverse agonist effects
Authors: Krobert Kurt A , Levy Finn Olav
Published: January 2005

Using membranes from stably or transiently transfected HEK293 cells cultured in 5‐HT‐free medium and expressing the recombinant human 5‐HT7 receptor splice variants (h5‐HT7(a), h5‐HT7(b) and h5‐HT7(d)), we compared their abilities to constitutively activate adenylyl cyclase (AC).

All h5‐HT7 splice variants elevated basal and forskolin‐stimulated AC. The basal AC activity was reduced by the 5‐HT7 antagonist methiothepin and this effect was blocked by mesulergine (neutral 5‐HT7 antagonist) indicating that the inhibitory effect of methiothepin is inverse agonism at the 5‐HT7 receptor.

Receptor density correlated poorly with constitutive AC activity in stable clonal cell lines and transiently transfected cells. Mean constitutive AC activity as a percentage of forskolin‐stimulated AC was significantly higher for the h5‐HT7(b) splice variant compared to the h5‐HT7(a) and h5‐HT7(d) splice variants but only in stable cell lines.

All eight 5‐HT antagonists tested inhibited constitutive AC activity of all splice variants in a concentration‐dependent manner. No differences in inverse agonist potencies (pIC50) were observed between the splice variants. The rank order of potencies was in agreement and highly correlated with antagonist potencies (pKb) determined by antagonism of 5‐HT‐stimulated AC activity (methiothepin>metergoline>mesulergineclozapinespiperoneritanserin>methysergide>ketanserin).

The efficacy of inverse agonism was not receptor level dependent and varied for several 5‐HT antagonists between membrane preparations of transiently and stably transfected cells.

It is concluded that the h5‐HT7 splice variants display similar constitutive activity and inverse agonist properties.

British Journal of Pharmacology (2002) 135, 1563–1571; doi:10.1038/sj.bjp.0704588
NCX‐701 (nitroparacetamol) is an effective antinociceptive agent in rat withdrawal reflexes and wind‐up
Authors: Romero‐Sandoval E Alfonso , Mazario Javier , Howat David , Herrero Juan F
Published: January 2005

Non‐steroidal anti‐inflammatory drugs (NSAIDs) are effective anti‐inflammatory and analgesic drugs although they also induce unwanted side effects due to the inhibition of the physiological effects regulated by prostaglandins. This has led to the search for new compounds with fewer side effects, such as the nitro‐NSAIDs (NO‐NSAIDs). Paracetamol is an analgesic drug devoid of some of the side effect of the NSAIDs but without anti‐inflammatory activity. NCX‐701 is a nitric oxide releasing version of paracetamol with anti‐inflammatory and analgesic properties.

We have tested, in the single motor unit technique, the antinociceptive actions of intravenous cumulative doses of NCX‐701 vs paracetamol, studying their antinociceptive effects in responses to noxious mechanical and electrical stimulation (wind‐up).

Paracetamol did not induce any significant effect at the doses tested (maximum of 480 μmol kg−1, 72.5 mg kg−1). NCX‐701 however was very effective in reducing responses to noxious mechanical stimulation (32±10% of control response) and wind‐up (ED50 of 147±1 μmol kg−1, 41.5±0.3 mg kg−1). The inhibition was not reversed by 1 mg kg−1 of the opioid antagonist naloxone. In control experiments performed with either the vehicle or the NO donor NOC‐18, no significant changes were observed in the nociceptive responses studied.

We conclude that NCX‐701 is a very effective non‐opioid antinociceptive agent in normal animals and its action is located mainly at central areas. The antinociceptive effect was not due solely to the release of NO.

British Journal of Pharmacology (2002) 135, 1556–1562; doi:10.1038/sj.bjp.0704589
The atypical 5‐HT2 receptor mediating tachycardia in pithed rats: pharmacological correlation with the 5‐HT2A receptor subtype
Authors: Centurión David , Ortiz Mario I , Saxena Pramod R , Villalón Carlos M
Published: January 2005

In pithed rats, 5‐HT mediates tachycardia both directly (by 5‐HT2 receptors) and indirectly (by a tyramine‐like effect). The receptor mediating tachycardia directly has been classified as an ‘atypical’ 5‐HT2 receptor since it was ‘weakly’ blocked by ketanserin. Moreover, 1‐(2,5‐dimethoxy‐4‐iodophenyl)‐2‐aminopropane (DOI), a 5‐HT2 agonist, failed to mimic 5‐HT‐induced tachycardia. Since 5‐HT2 receptors consist of 5‐HT2A, 5‐HT2B and 5‐HT2C subtypes, this study investigated if these subtypes mediate the above response.

In pithed rats, intraperitoneally (i.p.) pre‐treated with reserpine (5 mg kg−1), intravenous (i.v.) administration of 5‐HT, 5‐methoxytryptamine (5‐MeO‐T), 1‐(3‐chlorophenyl) piperazine (mCPP) and 5‐carboxamidotryptamine (5‐CT) (10, 30, 100 and 300 μg kg−1 each), produced dose‐dependent tachycardic responses. Interestingly, DOI (10 – 1000 μg kg−1, i.v.) induced only slight, dose‐unrelated, tachycardic responses, whilst the 5‐HT2C agonist, Ro 60‐0175 (10 – 1000 μg kg−1, i.v.), produced a slight tachycardia only at 300 and 1000 μg kg−1. In contrast, sumatriptan and 1‐(m‐trifluoromethylphenyl)‐ piperazine (TFMPP) were inactive. The rank order of potency was: 5‐HT5‐MeO‐T> mCPP5‐CTDOI>Ro 60‐0175.

The tachycardic responses to 5‐HT, which remained unaffected after i.v. saline (0.3 and 1 ml kg−1) or propranolol (3 mg kg−1), were selectively blocked by the 5‐HT2A antagonists ketanserin (30 and 100 μg kg−1) or spiperone (10 and 30 μg kg−1) as well as by the non‐selective 5‐HT2 antagonists, ritanserin (10 and 30 μg kg−1) or mesulergine (100 μg kg−1). Remarkably, these responses were unaffected by the antagonists rauwolscine (5‐HT2B), SB204741 (5‐HT2B/2C) or Ro 04‐6790 (5‐ht6) (300 and 1000 μg kg−1 each).

These results suggest that the ‘atypical’ 5‐HT2 receptors mediating tachycardia in reserpinized pithed rats are pharmacologically similar to the 5‐HT2A receptor subtype.

British Journal of Pharmacology (2002) 135, 1531–1539; doi:10.1038/sj.bjp.0704593
Store depletion‐induced calcium influx in rat cerebellar astrocytes
Authors: Lo Kuo‐Jung , Luk Hsiang‐Ning , Chin Ting‐Yu , Chueh Sheau‐Huei
Published: January 2005

In rat cerebellar astrocytes, intracellular Ca2+ store depletion by receptor agonists or sarco(endo)plasmic reticulum Ca2+ ATPase inhibitors induced a transient increase in the intracellular Ca2+ concentration ([Ca2+]i) in the absence of extracellular Ca2+ and a sustained increase in its presence.

After 10 min treatment with thapsigargin, the [Ca2+]i was unaffected by removal of thapsigargin, but fell rapidly to the basal level when extracellular Ca2+ was removed, suggesting the involvement of capacitative Ca2+ entry (CCE); this effect was not seen until cells had been exposed to thapsigargin for at least 2 min.

Using the whole cell voltage clamp technique, a 60 – 100 pA inward current was activated by store depletion, the reversal potential ranging from −5 to 0 mV.

When extracellular Na+ was isotonically replaced by Tris, the thapsigargin‐induced [Ca2+]i increase was enhanced, while the inward current was reduced, indicating that store‐operated Ca2+ channels were permeable to Na+; however, they were not permeable to Sr2+ or Ba2+.

Thapsigargin‐induced CCE remained the same in the presence of nifedipine, La3+ or Cd2+, while it was inhibited in the presence of SK&F96365.

In cerebellar astrocytes, inhibition of protein serine/threonine phosphorylation promoted CCE.

In conclusion, in rat cerebellar astrocytes, store depletion activated a CCE via channels which were permeable to Ca2+ and Na+ and regulated by phosphorylation.

British Journal of Pharmacology (2002) 135, 1383–1392; doi:10.1038/sj.bjp.0704594
Sensitizing effects of lafutidine on CGRP‐containing afferent nerves in the rat stomach
Authors: Nishihara Katsushi , Nozawa Yoshihisa , Nakano Motoko , Ajioka Hirofusa , Matsuura Naosuke
Published: January 2005

Capsaicin sensitive afferent nerves play an important role in gastric mucosal defensive mechanisms. Capsaicin stimulates afferent nerves and enhances the release of calcitonin gene‐related peptide (CGRP), which seems to be the predominant neurotransmitter of spinal afferents in the rat stomach, exerting many pharmacological effects by a direct mechanism or indirectly through second messengers such as nitric oxide (NO).

Lafutidine is a new type of anti‐ulcer drug, possessing both an antisecretory effect, exerted via histamine H2 receptor blockade, and gastroprotective activities. Studies with certain antagonists or chemical deafferentation techniques suggest the gastroprotective actions of lafutidine to be mediated by capsaicin sensitive afferent nerves, but this is an assumption based on indirect techniques. In order to explain the direct relation of lafutidine to afferent nerves, we conducted the following studies.

We determined CGRP and NO release from rat stomach and specific [3H]‐resiniferatoxin (RTX) binding to gastric vanilloid receptor subtype 1 (VR1), which binds capsaicin, using EIA, a microdialysis system and a radioreceptor assay, respectively.

Lafutidine enhanced both CGRP and NO release from the rat stomach induced by a submaximal dose of capsaicin, but had no effect on specific [3H]‐RTX and capsaicin binding to VR1.

In conclusion, our findings demonstrate that lafutidine modulates the activity of capsaicin sensitive afferent nerves in the rat stomach, which may be a key mechanism involved in its gastroprotective action.

British Journal of Pharmacology (2002) 135, 1487–1494; doi:10.1038/sj.bjp.0704596
The effects of neuroleptics on the GABA‐induced Cl−current in rat dorsal root ganglion neurons: differences between some neuroleptics
Authors: Yokota Kenjiro , Tatebayashi Hideharu , Matsuo Tadashi , Shoge Takashi , Motomura Haruhiko , Matsuno Toshiyuki , Fukuda Akira , Tashiro Nobutada
Published: January 2005

Several neuroleptics inhibited the 3 μMγ‐aminobutyric acid induced‐chloride current (GABA‐current) on dissociated rat dorsal root ganglion neurons in whole‐cell patch‐clamp investigations.

The IC50for clozapine, zotepine, olanzapine, risperidone and chlorpromazine were 6.95, 18.26, 20.30, 106.01 and 114.56 μM, respectively. The values for the inhibitory effects of neuroleptics on the GABA (3 μM)‐current, which were calculated by the fitting Hill's equations where the concentrations represent the mean therapeutic blood concentrations, were ranked clozapine>zotepine>chlorpromazine>olanzapine>risperidone. These inhibitory effects, weighted with the therapeutic concentrations of neuroleptics, were correlated with the clinical incidences of seizure during treatment with neuroleptics.

Clozapine reduced the picrotoxin‐inhibiton, and may compete with a ligand of the t‐butylbicyclophosphorothionate (TBPS) binding site.

Haloperidol and quetiapine did not affect the peak amplitude of the GABA (3 μM)‐current. However, haloperidol reduced the clozapine‐inhibition, and may antagonize ligand binding to TBPS binding site.

Neuroleptics including haloperidol and quetiapine enhanced the desensitization of the GABA (3 μM)‐current. However, haloperidol and quetiapine at 100 μMinhibited the desensitization at the beginning of application.

Blonanserin (AD‐5423) at 30 and 50 μMpotentiated the GABA (3 μM)‐current to 170.1±6.9 and 192.0±10.6% of the control current, respectively. Blonanserin shifted GABA concentration‐response curve leftward. Blonanserin only partly negatively interacted with diazepam. The blonanserin‐potentiation was not reversed by flumazenil. Blonanserin is not a benzodiazepine receptor agonist.

The various effects of neuroleptics on the GABA‐current may be related to the clinical effects including modifying the seizure threshold.

British Journal of Pharmacology(2002)135, 1547–1555; doi:10.1038/sj.bjp.0704608
An electrophysiological study of muscarinic and nicotinic receptors of rat paratracheal ganglion neurons and their inhibition by Z‐338
Authors: Kanemoto Yumiko , Ishibashi Hitoshi , Doi Atsushi , Akaike Norio , Ito Yushi
Published: January 2005

To study the mechanisms involved in the action of Z‐338, a newly synthesized gastroprokinetic agent, experiments were performed with the paratracheal ganglion cells acutely dissociated from 2‐week‐old Wistar rats. The effects of Z‐338 on both nicotinic and muscarinic responses of the ganglion cells were studied by nystatin perforated patch recording configuration under the current‐ and voltage‐clamp conditions.

Acetylcholine (ACh) or nicotine, and muscarine or oxotremorine‐M (OX‐M) induced membrane depolarization with rapid and slow time courses respectively, followed by repetitive generation of action potentials in the ganglion cell. Corresponding to the membrane depolarization induced by cholinergic agents, ACh induced biphasic inward currents with rapid and slow time courses under the voltage‐clamp condition. Nicotine and muscarine or OX‐M evoked inward currents with rapid and slow time courses, respectively. The rapid and slow inward currents were accompanied by increase and decrease in the membrane conductance, respectively. In addition, OX‐M dose‐dependently suppressed the M‐type K+ current evoked in response to hyperpolarizing voltage‐steps from VH of −25 mV to −50 mV, indicating that the activation of muscarinic acetylcholine receptors inhibits M‐type K+ current, thus inducing inward current in the ganglion cell.

Z‐338 competitively suppressed the inward currents induced by OX‐M through M1 ACh receptor, and uncompetitively suppressed the currents induced by nicotine.

The inhibitory actions of Z‐338 on the membrane depolarization and corresponding inward currents mediated by M1‐muscarinic and neuronal nicotinic ACh receptors in the isolated ganglion cells were discussed in relation to the inhibitory actions on autoreceptors in the parasympathetic nerve terminals, which would explain the gastroprokinetic actions of Z‐338.

British Journal of Pharmacology (2002) 135, 1403–1414; doi:10.1038/sj.bjp.0704610
Pharmacological profile of PKF242‐484 and PKF241‐466, novel dual inhibitors of TNF‐α converting enzyme and matrix metalloproteinases, in models of airway inflammation
Authors: Trifilieff Alexandre , Walker Christoph , Keller Thomas , Kottirsch Georg , Neumann Ulf
Published: January 2005

TNF‐α converting enzyme (TACE) and matrix metalloproteinases (MMPs) are believed to play a role in various airway inflammatory disorders. Therefore we have tested the effect of two new inhibitors of TACE/MMPs (PKF242‐484, PKF241‐466) in models of airway inflammation.

PKF242‐484 and PKF241‐466 inhibited purified MMP‐1, −2, −3, −9, −13 and rat collagenase at low nanomolar range. Both compounds inhibited the TNF‐α release from activated human peripheral blood mononuclear cells with IC50 values of 56±28 and 141±100 nM, respectively and had no significant effect on the activation of other human leukocytes, as neither neutrophils and eosinophils oxidative burst nor proliferation or cytokines production by T cells were inhibited in vitro.

PKF242‐484 and PKF241‐466 had beneficial effects in two different murine models of acute lung inflammation in vivo. The influx of neutrophils and lymphocytes into the airways was reduced 3 and 24 h after intranasal LPS challenge. This was accompanied by reduced levels of myeloperoxidase and elastase activities in the bronchoalveolar lavage. Furthermore, a complete inhibition of TNF‐α release into the airways was observed. In addition, PKF242‐484 effectively reduced the influx of neutrophils, eosinophils and lymphocytes in a model of acute allergic lung inflammation.

PKF242‐484 and PKF241‐466 are two novel and potent dual inhibitors of TACE and MMPs, which show activity in in vivo models of lung inflammation. Such compounds could have beneficial effects in airway inflammatory conditions such as asthma and chronic obstructive pulmonary disease.

British Journal of Pharmacology (2002) 135, 1655–1664; doi:10.1038/sj.bjp.0704616
Dexrazoxane pre‐treatment protects skinned rat cardiac trabeculae against delayed doxorubicin‐induced impairment of crossbridge kinetics
Authors: Beer Evert L de , Bottone Antonio E , Rijk Maartje C van , Velden Jolanda van der , Voest Emile E
Published: January 2005

Dexrazoxane (DXR, ICRF‐187) has been shown both in animal studies and clinical trials to provide a substantial cardioprotection when co‐administered with anthracycline drugs like Doxorubicin (DOX). In a previous study, we showed that chronic DOX treatment in rats is associated with a clear impairment of the crossbridge kinetics and shift in myosin iso‐enzymes.

The present study was adopted to investigate whether the cardioprotective action of DXR involves preservation of the normal actin‐myosin interaction. Rats were treated for 4 weeks with either DOX at a weekly dose of 2 mg kg−1 (i.v.), or were pre‐injected with DXR (40 mg kg−1, i.v.) at a 20 : 1 dose ratio 30 min prior to the DOX infusion. Rats receiving saline or DXR alone were included in the experiments. Cardiac trabeculae were isolated 4 weeks after the last infusion and were skinned with detergent.

Crossbridge turnover kinetics were studied after application of rapid length perturbations of varying amplitudes in Ca2+‐activated preparations. DXR treatment offered a significant protection against the DOX‐induced impairment of the crossbridge kinetics in isolated cardiac trabeculae. Time constants describing transitions between different crossbridge states were restored to normal in both the quick release protocol and the slack‐test. DXR prevented the shift from the ‘high ATPase’ α‐myosin heavy chain (MHC) isoform towards the ‘low‐ATPase’ β‐MHC isoform in the ventricles.

We conclude that pre‐administration of DXR in rats greatly reduces the deleterious effects of chronic DOX treatment on the trabecular actin – myosin crossbridge cycle. Preventing direct deleterious effects on the actin – myosin crossbridge system may provide a new target for preventing or reducing DOX‐related cardiotoxicity and may enable patients to continue the treatment beyond currently imposed limits.

British Journal of Pharmacology (2002) 135, 1707–1714; doi:10.1038/sj.bjp.0704621
Mutations inducing divergent shifts of constitutive activity reveal different modes of binding among catecholamine analogues to the β2‐adrenergic receptor
Authors: Carmine Renata Del , Ambrosio Caterina , Sbraccia Maria , Cotecchia Susanna , Ijzerman Adriaan P , Costa Tommaso
Published: January 2005

We compared the changes in binding energy generated by two mutations that shift in divergent directions the constitutive activity of the human β2 adrenergic receptor (β2AR).

A constitutively activating mutant (CAM) and the double alanine replacement (AA mutant) of catechol‐binding serines (S204A, S207A) in helix 5 were stably expressed in CHO cell lines, and used to measure the binding affinities of more than 40 adrenergic ligands. Moreover, the efficacy of the same group of compounds was determined as intrinsic activity for maximal adenylyl cyclase stimulation in wild‐type β2AR.

Although the two mutations had opposite effects on ligand affinity, the extents of change were in both cases largely correlated with the degree of ligand efficacy. This was particularly evident if the extra loss of binding energy due to hydrogen bond deletion in the AA mutant was taken into account. Thus the data demonstrate that there is an overall linkage between the configuration of the binding pocket and the intrinsic equilibrium between active and inactive receptor forms.

We also found that AA mutation‐induced affinity changes for catecholamine congeners gradually lacking ethanolamine substituents were linearly correlated to the loss of affinity that such modifications of the ligand cause for wild‐type receptor. This indicates that the strength of bonds between catechol ring and helix 5 is critically dependent on the rest of interactions of the β‐ethanolamine tail with other residues of the β2‐AR binding pocket.

British Journal of Pharmacology (2002) 135, 1715–1722; doi:10.1038/sj.bjp.0704622
Angiotensin‐(1‐7) is involved in the endothelium‐dependent modulation of phenylephrine‐induced contraction in the aorta of mRen‐2 transgenic rats
Authors: Lemos Virgínia S , Côrtes Steyner F , Silva Denise M R , Campagnole‐Santos Maria J , Santos Robson A S
Published: January 2005

The contribution of the local vascular production of angiotensin‐(1‐7) [Ang‐(1‐7)] to the control of α‐adrenergic‐induced contractions in the aorta of Sprague‐Dawley (SD) and TGR(mRen‐2)27 [mRen‐2] rats was studied.

In mRen‐2 rats, contractile responses to phenylephrine were diminished as compared to control SD rats in endothelium containing but not in endothelium‐denuded vessels. L‐NAME increased contractile responses to phenylephrine in mRen‐2 rats and, after nitric oxide synthase blockade, responses to phenylephrine became comparable in both strains.

Inhibition of angiotensin‐converting enzyme (ACE) by captopril potentiated contractile responses in mRen‐2 rats and diminished contractile responses in SD rats, both effects being dependent on the presence of a functional endothelium. The effect of captopril in mRen‐2 rats was abolished in vessels pre‐incubated with Ang‐(1‐7).

Blockade of Ang‐(1‐7) and bradykinin (BK) receptors by A‐779 and HOE 140 respectively, increased phenylephrine‐induced contraction in mRen‐2, but not in SD rats. This effect was seen only in endothelium‐containing vessels.

Angiotensin II AT1 and AT2 receptor blockade by CV 11974 and PD 123319 did not affect the contractile responses to phenylephrine in aortas of transgenic animals but diminished the response in SD rats. This effect was only seen in the presence of a functional endothelium.

It is concluded that the decreased contractile responses to phenylephrine in aortas of mRen‐2 rats was dependent on an intact endothelium, the local release and action of Ang‐(1‐7) and bradykinin.

British Journal of Pharmacology (2002) 135, 1743–1748; doi:10.1038/sj.bjp.0704630
Quercetin as a novel activator of L‐type Ca2+channels in rat tail artery smooth muscle cells
Authors: Saponara Simona , Sgaragli Giampietro , Fusi Fabio
Published: January 2005

The aim of this study was to investigate the effects of quercetin, a natural polyphenolic flavonoid, on voltage‐dependent Ca2+channels of smooth muscle cells freshly isolated from the rat tail artery, using either the conventional or the amphotericin B‐perforated whole‐cell patch‐clamp method.

Quercetin increased L‐type Ca2+current [ICa(L)] in a concentration‐ (pEC50=5.09±0.05) and voltage‐dependent manner and shifted the maximum of the current‐voltage relationship by 10 mV in the hyperpolarizing direction, without, however, modifying the threshold and the equilibrium potential for Ca2+. Quercetin‐induced ICa(L)stimulation was reversible upon wash‐out. T‐type Ca2+current was not affected by quercetin.

Quercetin shifted the voltage dependence of the steady‐state inactivation and activation curves to more negative potentials by about 5.5 and 7.5 mV respectively, in the mid‐potential of the curves as well as increasing the slope of activation. Quercetin slowed both the activation and the deactivation kinetics of the ICa(L). The inactivation time course was also slowed but only at voltages higher than 10 mV. Moreover quercetin slowed the rate of recovery from inactivation.

These results prove quercetin to be a naturally‐occurring L‐type Ca2+channel activator.

British Journal of Pharmacology(2002)135, 1819–1827; doi:10.1038/sj.bjp.0704631
The protective effect of resveratrols on ischaemia‐reperfusion injuries of rat hearts is correlated with antioxidant efficacy
Authors: Hung Li‐Man , Su Ming‐Jai , Chu Wing‐Keung , Chiao Chin‐Wei , Chan Wan‐Fen , Chen Jan‐Kan
Published: January 2005

Dietary antioxidants are thought to be beneficial in reducing the incidence of coronary heart disease. In this study, we compared resveratrol and analogues on their antioxidation and free radical scavenging activities to their protective effects on ischaemia‐reperfusion induced injuries of rat hearts.

Astringinin (3,3′,4′,5‐tetrahydroxystilbene) was shown to be a more potent inhibitor than other analogues against Cu2+‐induced LDL (low‐density lipoprotein) oxidation, as measured by the formation of conjugated diene and TBARS (thiobarbituric acid‐reactive substance) and by the electrophoretic mobility of the oxidized LDL.

Resveratrol (trans‐3,4′,5‐trihydroxystilbene) and astringinin scavenged the stable free radical DPPH (1,1‐diphenyl‐2‐picryl‐hydrazyl) with an IC0.200 of 7.1 and 4.3 μM, respectively.

Astringinin has a superoxide anion scavenging activity about 160 fold more potent than resveratrol.

After a 30 min global ischemia followed by 2 h reperfusion, astringinin (10 μM) significantly reduced infarct size, superoxide anion production and increased functional recovery of the coronary flow in Langendorff‐perfused rat hearts.

The result showed there is a positive correlation between the anti‐oxidation and cardioprotective activities among these phenolic compounds. Our finding together with the fact that astringinin is more water‐soluble than resveratrol suggest that astringinin could potentially be used as an anti‐oxidant and cardioprotective agent in biological systems.

British Journal of Pharmacology (2002) 135, 1627–1633; doi:10.1038/sj.bjp.0704637
Leukocyte rolling is exclusively mediated by P‐selectinin colonic venules
Authors: Wan Ming Xiu , Riaz Amjid Ali , Schramm Rene , Wang Yusheng , Vestweber Dietmar , Menger Michael D , Thorlacius Henrik
Published: January 2005

The objective of the present study was to examine the role of the endothelial selectins (i.e. P‐ and E‐selectin) in leukocyte‐endothelium interactions in colonic venules by use of intravital microscopy.

Balb/c mice were exposed to dextran sodium sulphate (DSS) in the drinking water for 5 days or treated intraperitoneally (i.p.) with tumour necrosis factor‐α (TNF‐α) for 3 h.

In DSS‐treated mice, mRNA of both P‐ and E‐selectin were expressed and leukocyte rolling and adhesion was increased to 27±3 cells min−1 and 36±8 cells mm−1, respectively. An anti‐P‐selectin antibody abolished DSS‐induced leukocyte rolling, whereas an antibody against E‐selectin had no effect. Established leukocyte adhesion was insensitive to inhibition of the selectins.

DSS markedly increased production of TNF‐α in the colon. TNF‐α increased leukocyte rolling to 22±3 cells min−1 and adhesion to 45±4 cells mm−1. Only inhibition of P‐selectin significantly reduced (>94%) leukocyte rolling provoked by TNF‐α. Leukocyte adhesion was not changed by late anti‐P‐selectin antibody treatment. In contrast, pretreatment with the anti‐P‐selectin antibody not only abolished leukocyte rolling but also completely inhibited firm adhesion in response to TNF‐α.

This study demonstrates that P‐selectin plays an important role in leukocyte rolling in colonic venules, both in experimental colitis and when stimulated with TNF‐α. Moreover, P‐selectin‐dependent leukocyte rolling was found to be a precondition for TNF‐α‐induced firm adhesion. Thus, these findings suggest that P‐selectin may be a key target to reduce pathological recruitment of inflammatory cells in the colon.

British Journal of Pharmacology (2002) 135, 1749–1756; doi:10.1038/sj.bjp.0704638