bluuebunny/crossref_metadata_2025 huggingface dataset:
Suppression of human inflammatory cell function by subtype‐selective PDE4 inhibitors correlates with inhibition of PDE4A and PDE4B
Authors: Manning Carol D , Burman Miriam , Christensen Siegfried B , Cieslinski Lenora B , Essayan David M , Grous Marilyn , Torphy Theodore J , Barnette Mary S
Published: January 2005

Of the four major phosphodiesterase 4 (PDE4) subtypes, PDE4A, PDE4B and PDE4D are widely expressed in human inflammatory cells, including monocytes and T lymphocytes. We explored the functional role of these subtypes using ten subtype‐selective PDE4 inhibitors, each belonging to one of two classes: (i) dual PDE4A/PDE4B inhibitors or (ii) PDE4D inhibitors.

These compounds were evaluated for their ability to inhibit antigen‐stimulated T‐cell proliferation and bacterial lipopolysaccharide (LPS)‐stimulated tumour necrosis factor α (TNFα) release from peripheral blood monocytes.

All compounds inhibited T‐cell proliferation in a concentration‐dependent manner; with IC50 values distributed over an approximately 50 fold range. These compounds also inhibited TNFα release concentration‐dependently, with a wider (∼1000 fold) range of IC50 values.

In both sets of experiments, mean IC50 values were significantly correlated with compound potency against the catalytic activity of recombinant human PDE4A or PDE4B when analysed by either linear regression of log IC50 values or by Spearman's rank‐order correlation. The correlation between inhibition of inflammatory cell function and inhibition of recombinant PDE4D catalytic activity was not significant in either analysis.

These results suggest that PDE4A and/or PDE4B may play the major role in regulating these two inflammatory cell functions but do not rule out PDE4D as an important mediator of other activities in mononuclear leukocytes and other immune and inflammatory cells. Much more work is needed to establish the functional roles of the PDE4 subtypes across a broader range of cellular functions and cell types.

British Journal of Pharmacology (1999) 128, 1393–1398; doi:10.1038/sj.bjp.0702911
Leukotrienes are involved in leukocyte recruitment induced by live Histoplasma capsulatum or by the β‐glucan present in their cell wall
Authors: Medeiros Alexandra I , Silva Célio L , Malheiro Adriana , Maffei Cláudia M L , Faccioli Lúcia H
Published: January 2005

The inflammatory cell influx towards the peritoneal cavity in mice inoculated i.p. with live or dead Histoplasma capsulatum or with its subcellular preparations was studied. We also evaluated the effects of dexamethasone (Dexa) or MK886, an inhibitor of leukotriene (LT) biosynthesis, on the recruitment of leukocytes.

Live yeast form of fungus (LYH) induced an increase in neutrophils (NE) which was highest 4 to 24 h after inoculation. Mononuclear cell (MN) migration beginning at 24 h with a gradual increase over 48 and 168 h, and an eosinophil (EO) recruitment occurs between 24 and 48 h.

NE and EO recruitment induced by dead mycelial form of fungus (DMH) was greater than that observed for dead yeast form of fungus (DYH). A similar leukocyte migration pattern was seen after i.p. injection of the alkali‐insoluble fraction (F1) from DYH (F1Y) and F1 from DMH (F1M) this being more active than former. The difference in concentration of β‐glucan in DYH and DMH could explain the different inflammatory capacity exhibited by the two forms of H. capsulatum.

LT seems to be the principal mediator of leukocyte migration in response to LYH, DYH or DMH or to β‐glucan. However, other mediators appear to contribute to NE and EO migration since the treatment with Dexa was more effective in inhibiting cell migration than MK886. Complement dependent leukocyte migration may participate in this recruitment. Treatment with MK886 completely abolished MN cell migration, indicating its dependence on the presence of LT.

British Journal of Pharmacology (1999) 128, 1529–1537; doi:10.1038/sj.bjp.0702912
S 15535, a benzodioxopiperazine acting as presynaptic agonist and postsynaptic 5‐HT1A receptor antagonist, prevents the impairment of spatial learning caused by intrahippocampal scopolamine
Authors: Carli Mirjana , Balducci Claudia , Millan Mark J , Bonalumi Pierenrico , Samanin Rosario
Published: January 2005

The effect of S 15535 (4‐benzodioxan‐5‐yl)1‐(indan‐2‐yl)piperazine), an agonist at presynaptic and antagonist at postsynaptic 5‐HT1A receptors, on the impairment of spatial learning caused by intrahippocampal scopolamine in a two‐platform spatial discrimination task was studied.

Scopolamine (4.0 μg μl−1), injected bilaterally into the CA1 region of the dorsal hippocampus 10 min before each training session, impaired choice accuracy with no effect on choice latency and errors of omission.

Administered subcutaneously 30 min before each training session, S 15535 1.0 (but not 0.3) mg kg−1 did not modify choice accuracy but prevented its impairment by intrahippocampal scopolamine.

WAY 100635, a 5‐HT1A receptor antagonist, injected into the dorsal raphe at 1.0 μg 0.5 μl−1 5 min before scopolamine, had no effect on choice accuracy and latency or errors of omission and did not modify the effect of scopolamine but completely antagonized the effect of S 15535 (1.0 mg kg−1) on scopolamine‐induced impairment of choice accuracy.

The results confirm a previous report (Carli et al., 1998) that stimulation of presynaptic 5‐HT1A receptors in the dorsal raphe counteracts the deficit caused by intrahippocampal scopolamine, probably by facilitating the transfer of facilitatory information from the entorhinal cortex to the hippocampus.

Drugs that stimulate action on presynaptic 5‐HT1A receptors, such as S 15535 and other partial 5‐HT1A receptors agonists, may be useful in the symptomatic treatment of human memory disturbances associated with loss of cholinergic innervation to the hippocampus.

British Journal of Pharmacology (1999) 128, 1207–1214; doi:10.1038/sj.bjp.0702915
Non‐adrenergic binding of [3H]atipamezole in rat kidney–regional distribution and comparison to α2‐adrenoceptors
Authors: Sjöholm Birgitta , Lähdesmäki Janne , Pyykkö Kaija , Hillilä Maarit , Scheinin Mika
Published: January 2005

Atipamezole (4‐(2‐ethyl‐2,3‐dihydro‐1H‐inden‐2‐yl)‐1H‐imidazole) was first introduced as a potent and specific α2‐adrenoceptor antagonist, but in some tissues [3H]atipamezole identifies an additional population of binding sites, distinct from both classical α2‐adrenoceptors and I1‐ and I2‐imidazoline receptors identified with [3H]para‐aminoclonidine or [3H]idazoxan.

In the present study we have characterized [3H]atipamezole binding sites in rat kidney by receptor autoradiography and membrane binding assays and determined whether they are pharmacologically identical with the previously described binding sites for [3H]para‐aminoclonidine and [3H]idazoxan. [3H]RX821002 and [3H]rauwolscine were used to compare the regional distribution of α2‐adrenoceptors to that of non‐adrenergic binding sites of [3H]atipamezole.

Comparative autoradiographic experiments demonstrated the differential localisation of [3H]atipamezole, [3H]RX821002 and [3H]rauwolscine binding sites in rat kidney. The pattern of distribution of non‐adrenergic [3H]atipamezole binding sites is clearly distinct from that of α2‐adrenoceptors.

The non‐adrenergic binding of [3H]atipamezole in rat kidney does not fall into any of the previously identified three classes of imidazoline receptors studied with [3H]para‐aminoclonidine, [3H]idazoxan and [3H]RX821002.

Atipamezole had no inhibitory effect on MAO‐A or MAO‐B activity in renal membranes, which speaks against the involvement of MAOs in the observed radioligand binding.

British Journal of Pharmacology (1999) 128, 1215–1222; doi:10.1038/sj.bjp.0702917
Desensitization and resensitization of β1‐ and putative β4‐adrenoceptor mediated responses occur in parallel in a rat model of cardiac failure
Authors: Kompa Andrew R , Summers Roger J
Published: January 2005

Cardiostimulant effects of the non‐conventional partial agonist, CGP 12177A, are mediated by a receptor distinct from the β3‐adrenoceptor and termed the putative β4‐adrenoceptor. Using a rat model of cardiac failure, induced by myocardial infarction (MI), we compared the desensitization and resensitization of responses to CGP 12177A with those to isoprenaline and RO 363 in left (LA) and right atria (RA). We also examined the ability of β‐adrenoceptor antagonists to block responses to CGP 12177A.

MI reduced the maximum inotropic response to isoprenaline by 48% (sham 4.1±0.6 mN, n=10; MI 2.1±0.4 mN, n=8, P<0.02), RO 363 by 61% (sham 4.2±0.5 mN, n=10; MI 1.8±0.3 mN, n=8, P<0.005) and CGP 12177A by 49% (sham 1.4±0.1 mN, n=5; MI 0.7±0.2 mN, n=7, P<0.05) in electrically stimulated LA. MI also reduced the sensitivity to isoprenaline (pEC50: sham 8.79±0.08, n=10; MI 8.30±0.10, n=8; P=0.001) and RO 363 (pEC50: sham 8.69±0.07, n=10; MI 8.33±0.10, n=8; P<0.01). The maximum chronotropic responses to isoprenaline, RO 363 and CGP 12177A in RA were unaffected.

Pertussis toxin treatment (10 μg kg−1, i.p.) restored the maximum inotropic response and sensitivity to isoprenaline (sham 3.5±0.5 mN, n=9; MI 3.2±0.6 mN, n=11, P=0.702) and CGP 12177A (sham 1.6±0.3 mN, n=6; MI 1.9±0.4 mN, n=7, P=0.537) in MI animals to levels similar to those in the sham group.

CGP 20712A (pKB: LA 6.7±0.2, n=6; RA 7.1±0.1, n=4), ICI 118,551 (pKB: LA 6.4±0.1, n=5; RA 6.3±0.1, n=6), propranolol (pKB: LA 6.6±0.1, n=5; RA 6.8±0.1, n=6) and bupranolol (pKB: LA 7.2±0.1, n=6; RA 7.7±0.1, n=8), showed moderate affinity for the putative β4‐adrenoceptor.

Desensitization after MI and resensitization (after pertussis toxin treatment) to isoprenaline and CGP 12177A therefore occur in parallel, suggesting that the β1‐ and putative β4‐adrenoceptor use the same signalling pathway. Antagonist affinity studies confirmed that drugs acting at β1‐adrenoceptors also interact with putative β4‐adrenoceptors with approximately 100 times lower affinity. We suggest that CGP 12177A produces its cardiac effects by interacting with a low affinity state of the β1‐adrenoceptor.

British Journal of Pharmacology (1999) 128, 1399–1406; doi:10.1038/sj.bjp.0702920
Release of nitric oxide from endothelial cells stimulated by YC‐1, an activator of soluble guanylyl cyclase
Authors: Wohlfart Paulus , Malinski Tadeusz , Ruetten Hartmut , Schindler Ursula , Linz Wolfgang , Schoenafinger Karl , Strobel Hartmut , Wiemer Gabriele
Published: January 2005

In this study we examined the endothelium‐dependent effect of YC‐1–a benzyl indazole derivative which directly activates soluble guanylyl cyclase (sGC)–on vascular relaxation and nitric oxide (NO) and guanosine‐3′,5′‐cyclic monophosphate (cyclic GMP) in endothelial cells.

In preconstricted rat aortic rings with intact endothelium, YC‐1 produced a concentration‐dependent relaxation. However, the concentration response curve was shifted rightward to higher concentrations of YC‐1, when (i) the aortas were pre‐treated with L‐NG‐nitroarginine methylester (L‐NAME) or (ii) the endothelium was removed.

Incubation of bovine aortic endothelial cells (BAEC) with YC‐1 produced a concentration‐dependent NO synthesis and release as assessed using a porphyrinic microsensor. Pre‐incubating cells with L‐NAME or with 8‐bromo‐cyclic GMP decreased this effect indicating that the YC‐1 stimulation of NO synthesis is due to an activation of nitric oxide synthase, but not to an elevation of cyclic GMP. No direct effect of YC‐1 on recombinant endothelial constitutive NO synthase activity was observed.

The YC‐1 stimulated NO release was reduced by 90%, when extracellular free calcium was diminished.

In human umbilical vein endothelial cells (HUVEC), YC‐1 stimulated intracellular cyclic GMP production in a concentration‐ and time‐dependent manner. Stimulation of cyclic GMP was greater with a maximum concentration of YC‐1 compared to calcium ionophore A23187. Similar effects were observed in BAEC and rat microvascular coronary endothelial cells (RMCEC).

When HUVEC and RMCEC were pre‐treated with L‐NG‐nitroarginine (L‐NOARG), the maximum YC‐1 stimulated cyclic GMP increase was reduced by 50%.

These results indicate, that beside being a direct activator of sGC, YC‐1 stimulates a NO‐synthesis and release in endothelial cells which is independent of elevation of cyclic GMP but strictly dependent on extracellular calcium. The underlying mechanism needs to be determined further.

British Journal of Pharmacology (1999) 128, 1316–1322; doi:10.1038/sj.bjp.0702921
Continued morphine modulation of calcium channel currents in acutely isolated locus coeruleus neurons from morphine‐dependent rats
Authors: Connor Mark , Borgland Stephanie L , Christie Macdonald J
Published: January 2005

The actions of the opioid agonists morphine and methionine‐enkephalin (met‐enkephalin) on the calcium channel currents (IBa) of acutely isolated locus coeruleus (LC) neurons from morphine‐dependent and vehicle‐treated rats were examined using whole cell patch clamp techniques.

In LC neurons maintained in 5 μM morphine, co‐superfusion of naloxone (1 μM) or the μ‐opioid receptor antagonist CTAP (D‐Phe‐Cys‐Tyr‐D‐Trp‐Arg‐Thr‐Pen‐Thr‐NH2 1 μM) with morphine resulted in a significant increase in the amplitude of IBa. The increases in IBa were not different in neurons from morphine‐dependent or vehicle rats. The increase in IBa was mimicked by washing off morphine, but not by co‐superfusion of the κ‐receptor antagonist norbinaltorphimine (300 nM) or the δ‐receptor antagonist ICI‐174864 (1 μM).

In spontaneously withdrawn LC neurons from morphine‐dependent rats, met‐enkephalin (pD2 7.1, maximum inhibition 49%) and morphine (pD2 6.5, maximum inhibition 33%), inhibited IBa in all cells. In cells from vehicle rats the pD2 for met‐enkephalin was 7.3, maximum inhibition 52%, while the pD2 for morphine was 6.6 and the maximum inhibition 43% (P<0.05 versus cells from morphine‐dependent rats).

IBa in LC neurons was mostly comprised of ω‐conotoxin GVIA‐ (N‐type) and ω‐agatoxin IVA‐ (P/Q‐type) sensitive components, with lesser amounts of nimodipine‐sensitive current and current resistant to all three blockers. Neither the density of IBa nor the proportion of any of the components of IBa differed between neurons from morphine‐dependent or vehicle‐treated rats.

This study demonstrates that in morphine‐dependent rats, morphine and met‐enkephalin modulation of somatic IBa in LC neurons displays modest tolerance compared with untreated rats. Further, chronic morphine treatment does not alter the type or density of IBa in LC neurons. These results provide more evidence that functional μ‐opioid receptor coupling is not dramatically altered in the LC in morphine‐dependent rats.

British Journal of Pharmacology (1999) 128, 1561–1569; doi:10.1038/sj.bjp.0702922
Vasodilator effects of sodium nitroprusside, levcromakalim and their combination in isolated rat aorta
Authors: Pérez‐Vizcaíno Francisco , Cogolludo Angel L , Zaragozá‐Arnáez Francisco , Fajardo Susana , Ibarra Manuel , López‐López J G , Tamargo Juan
Published: January 2005

The endothelial modulation of the relaxant responses to the nitric oxide (NO) donor sodium nitroprusside (SNP) and the KATP channel opener levcromakalim (LEM) and the interactions between these agents were analysed in isolated rat aorta.

LEM‐induced relaxation was unchanged by endothelium removal or by the presence of L‐NAME (10−4 M) or ODQ (10−6 M). In contrast, in KCl‐ (25 mM), but not in noradrenaline‐ (NA, 10−6 M) contracted arteries, SNP‐induced relaxation was augmented by endothelium removal but not by L‐NAME, indomethacin, glibenclamide nor charybdotoxin plus apamin.

The isobolographic analysis of the interactions between exogenously activated KATP channels and cyclic GMP using mixtures of SNP and LEM revealed that there were no interactions between both drugs at the proportions at which both drugs were active. However, the points for the SNP : LEM mixtures in proportions 10 : 1 and 1 : 10,000 (i.e. at concentrations at which LEM and SNP were inactive, respectively) fell significantly above the line of additivity indicating that there were negative interactions between both drugs at these selected proportions (about 5‐ and 2 fold inhibition, respectively). The former interaction was sensitive to glibenclamide, whereas the latter was insensitive ODQ. The magnitude of the 10 : 1 SNP : LEM interaction was smaller in endothelium‐intact arteries and was absent in arteries stimulated by NA.

In conclusion, the relaxations induced by LEM and SNP were additive. However, the presence of endothelium and low concentrations of LEM inhibited SNP‐induced relaxation. Both inhibitory effects were not additive and were only observed in KCl‐ and not in NA‐contracted aortae.

British Journal of Pharmacology (1999) 128, 1419–1426; doi:10.1038/sj.bjp.0702924
Effects of inhibitors of the activity of poly (ADP‐ribose) synthetase on the organ injury and dysfunction caused by haemorrhagic shock
Authors: McDonald Michelle C , Filipe Helder Mota , Thiemermann Christoph
Published: January 2005

Poly (ADP‐ribose) synthetase (PARS) is a nuclear enzyme activated by strand breaks in DNA, which are caused by reactive oxygen species (ROS). Here we investigate the effects of the PARS inhibitors 3‐aminobenzamide (3‐AB), nicotinamide and 1,5‐dihydroxyisoquinoline (ISO) on the circulatory failure and the organ injury/dysfunction caused by haemorrhage and resuscitation in the anaesthetized rat.

Haemorrhage (sufficient to lower mean arterial blood pressure to 50 mmHg for 90 min) and subsequent resuscitation with shed blood resulted (within 4 h after resuscitation) in a delayed fall in blood pressure to 66±4 mmHg (control, n=13). This circulatory failure was not affected by administration (5 min prior to resuscitation) of 3‐AB (10 mg kg−1 i.v., n=7), nicotinamide (10 mg kg−1 i.v., n=6) or ISO (3 mg kg−1 i.v., n=6).

Haemorrhage and resuscitation also resulted in rises in the serum levels of urea and creatinine. This renal dysfunction was attenuated by 3‐AB and nicotinamide, but not by nicotinic acid (n=7), an inactive analogue of nicotinamide. Although ISO (n=6) also attenuated the renal dysfunction caused by haemorrhage and resuscitation, its vehicle (10% DMSO, n=4) had the same effect.

Haemorrhagic shock resulted in enhanced serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and lipase, indicating the development of hepatocellular and pancreatic injury, respectively. Similarly, haemorrhagic shock also resulted in an increase in the serum levels of creatine kinase (CK) indicating the development of neuromuscular injury. This was attenuated by 3‐AB and nicotinamide, but not by nicotinic acid. Although ISO also attenuated the liver, pancreatic and neuromuscular injury caused by haemorrhagic shock, its vehicle had the same effect.

Thus, activation of PARS contributes to the organ injury and dysfunction caused by haemorrhage and resuscitation in the rat.

British Journal of Pharmacology (1999) 128, 1339–1345; doi:10.1038/sj.bjp.0702928
Endothelin alters the reactivity of vasa vasorum: mechanisms and implications for conduit vessel physiology and pathophysiology
Authors: Scotland Ramona , Vallance Patrick , Ahluwalia Amrita
Published: January 2005

The walls of certain large blood vessels are nourished by the vasa vasorum, a network of microvessels that penetrate the adventitia and media of the vessel wall. The purpose of this study was to characterize endothelin‐1 (ET‐1)‐mediated contraction of vasa and to investigate whether threshold concentrations of ET‐1 alters the sensitivity to constrictors. Arterial vasa were dissected from the walls of porcine thoracic aorta and mounted in a tension myograph.

ET‐1 and ETB‐selective agonist, sarafotoxin 6c (S6c), produced concentration‐dependent contraction. ETA receptor antagonist, BQ123 (10 μM), caused a biphasic rightward shift of ET‐1 response curves. ETB receptor antagonist, BQ788 (1 μM), produced a rightward shift of response curves to ET‐1 and S6c of 5‐ and 80 fold respectively.

ET‐1 responses were abolished in Ca2+‐free PSS but unaffected by selective depletion of intracellular Ca2+ stores. Nifedipine (10 μM), an L‐type Ca2+ channel blocker, attenuated ET‐1 responses by 44%. Inhibition of receptor‐operated Ca2+ channels or non‐selective cation entry using SKF 96365 (30 μM) and Ni2+ (1 mM) respectively, attenuated ET‐1 contractions by 60%.

ET‐1 (1–3 nM) enhanced responses to noradrenaline (NA) (4 fold) but not to thromboxane A2‐mimetic, whilst K+ (10–20 mM) sensitized vasa to both types of constrictor.

Therefore, ET‐1‐induced contraction of isolated vasa is mediated by ETA and ETB receptors and involves Ca2+ influx through L‐type and non‐L‐type Ca2+ channels. Furthermore elevation of basal tone of vasa vasorum alters the profile of contractile reactivity. These results suggest that ET‐1 may be an important regulator of vasa vasorum reactivity.

British Journal of Pharmacology (1999) 128, 1229–1234; doi:10.1038/sj.bjp.0702930
Effects of antisense oligonucleotides on brain delta‐opioid receptor density and on SNC80‐induced locomotor stimulation and colonic transit inhibition in rats
Authors: Negri Lucia , Broccardo Maria , Lattanzi Roberta , Melchiorri Pietro
Published: January 2005

To reduce the density of δ‐opioid receptor protein, five antisense phosphorothioate oligodeoxynucleotides (aODN), targeting the three exons of rat δ‐opioid receptor mRNA (DOR), were injected twice daily for 4 days or continuously infused for 7 days into brain lateral ventricles (i.c.v.) of Sprague‐Dawley rats. Rats acting as controls were infused or injected with a mismatch sequence (mODN) of each aODN. The density of opioid receptors in rat brain membranes was measured by saturation binding experiments using selective ligands for δ, μ and κ opioid receptors.

aODNs injected twice a day for 4 days left rat brain δ‐opioid receptor density unchanged. The ODN targeting the DOR nucleotide sequence 280–299 (aODN280–299, exon 2), decreased brain δ‐opioid receptor density significantly more than aODNs targeting exon 1 (aODN239–258), exon 2 (aODN361–380), or exon 3 (aODN741–760) (to 52% vs 79, 72, and 68%). None of the aODNs to the DOR changed the brain density of μ‐ or k‐opioid receptors.

When in a novel environment (but not when kept in their home cages), the locomotor activity of aODN280–299 treated rats was significantly lower than that of saline or mODN treated rats. The δ‐opioid agonist SNC80 (5 mg kg−1, s.c.) significantly and potently stimulated locomotion and delayed colonic propulsion in saline‐ and mODN‐infused rats, but left motor behaviour and colonic transit of δ‐knockdown rats unchanged.

The baseline nociceptive threshold and the antinociceptive response to morphine were unchanged in δ‐knockdown rats.

British Journal of Pharmacology (1999) 128, 1554–1560; doi:10.1038/sj.bjp.0702931
Pharmacological characterization of antagonists of the C5a receptor
Authors: Paczkowski Natalii J , Finch Angela M , Whitmore Jacqueline B , Short Anna J , Wong Allan K , Monk Peter N , Cain Stuart A , Fairlie David P , Taylor Stephen M
Published: January 2005

Potent and highly selective small molecule antagonists have recently been developed by us for C5a receptors (C5aR) on human polymorphonuclear leukocytes (PMN). In this study we compared a new cyclic antagonist, F‐[OPdChaWR], with an acyclic derivative, MeFKPdChaWr, for their capacities to bind to C5aR on human PMN and human umbilical artery membranes. We also compared their inhibition of myeloperoxidase (MPO) secretion from human PMNs and their inhibition of human umbilical artery contraction induced by human recombinant C5a.

In both PMNs and umbilical artery, the cyclic and acyclic C5a antagonists displayed insurmountable antagonism against C5a. There were differences in selectivities for the C5aR with F‐[OPdChaWR] (pKb 8.64±0.21) being 30 times more potent than MeFKPdChaWr (pKb 7.16±0.11, P<0.05) in PMNs, but of similar potency (pKb 8.19±0.38 vs pKb 8.28±0.29, respectively) in umbilical artery. This trend was also reflected in their relative binding affinities, both antagonists having similar affinities (−logIC50 values) for C5aR in umbilical artery membranes (F‐[OPdChaWR], 7.00±0.46; MeFKPdChaWr, 7.23±0.17), whereas in PMN membranes the C5aR affinity of the cycle F‐[OPdChaWR] (7.05±0.06) was four times higher than that of acyclic MeFKPdChaWr (6.43±0.24, P<0.05).

In summary, the results reveal that these antagonists are insurmountable in nature against C5a for C5aR on at least two human cell types, and the differences in relative receptor binding affinities and antagonistic potencies against C5a are consistent with differences in receptors within these cell types. The nature of these differences is yet to be elucidated.

British Journal of Pharmacology (1999) 128, 1461–1466; doi:10.1038/sj.bjp.0702938
The adrenergic receptor agonist, clonidine, potentiates the anti‐parkinsonian action of the selective κ‐opioid receptor agonist, enadoline, in the monoamine‐depleted rat
Authors: Hill M P , Brotchie J M
Published: January 2005

The treatment of Parkinson's disease relies predominantly upon dopamine replacement therapy, usually with l‐dihydroxyphenylalanine (L‐DOPA). However, side‐effects of long‐term treatment, such as L‐DOPA‐induced dyskinesias can be more debilitating than the disease itself. Non‐dopaminergic treatment strategies might therefore be advantageous.

The aim of this study was to investigate the potential anti‐parkinsonian efficacy of the κ‐opioid receptor agonist, enadoline, and the α‐adrenoreceptor agonist, clonidine, both alone or in combination, in the reserpine‐treated rat model of Parkinson's disease.

Rats were treated with reserpine (3 mg kg−1), and experiments carried out 18 h later, at which time they exhibited profound akinesia (normal animals 1251±228 mobile counts h−1, reserpine‐treated animals 9±2 mobile counts h−1). Both enadoline and clonidine increased locomotion in reserpine‐treated rats in a dose‐dependent manner. The maximum locomotor‐stimulating effect of enadoline alone was seen at a dose of 0.2 mg kg−1 (208±63 mobile counts h−1). The maximum effect of clonidine was seen at a dose of 2 mg kg−1 (536±184 mobile counts h−1).

Co‐administration of enadoline (0.1 mg kg−1) and clonidine (0.01–0.1 mg kg−1) at sub‐threshold doses, synergistically increased locomotion.

The synergistic stimulation of locomotion in the reserpine‐treated rat involved activation of κ‐opioid receptors and a combination of both α1 and α2‐adrenoreceptors.

The results presented suggest a need for further studies on the potential of stimulating κ‐opioid and/or α‐adrenoreceptors as a therapy for Parkinson's disease. Furthermore, the studies may offer potential mechanistic explanations of the ability of α2‐adrenergic receptor antagonist to reduce L‐DOPA‐induced dyskinesia in Parkinson's disease.

British Journal of Pharmacology (1999) 128, 1577–1585; doi:10.1038/sj.bjp.0702943
Sustained improvement in glucose homeostasis in lean and obese mice following chronic administration of the β3 agonist SR 58611A
Authors: Williams Celia A , Shih Mei‐Fen , Taberner Peter V
Published: January 2005

Acute SR 58611A (0.25 mg kg−1), was effective in reducing the blood glucose response to a glucose tolerance test (GTT) in normal lean (control) and spontaneously obese/diabetic CBA/Ca mice and to be equipotent to 1.25 mg kg−1 glibenclamide in lean mice.

Neither brown (BAT) nor white (WAT) adipose tissue lipogenesis was altered by acute SR 58611A (2–8 mg kg−1) in lean mice, but both increased significantly at the higher doses in the obese mice.

Acute SR 58611A produced a hypoglycaemia 40 min after dosing in lean and obese animals, the duration and potency of which was less than that of glibenclamide. Plasma insulin levels increased 20 min after acute SR 58611A and glibenclamide in lean and obese mice.

Chronic treatment (0.25 mg kg−1, 15 days) with SR 58611A increased its effectiveness in improving glucose tolerance, but did not affect the body weight (BW) or food intake of either lean or obese mice.

Acute and chronic SR 58611A prolonged the hypoglycaemic effect of exogenous insulin in lean but not obese mice.

In fed and fasted lean mice and in fasted obese mice chronic SR 58611A produced an acute hypoglycaemia 30 min post administration which was greater than after a single dose.

SR 58611A maintained its effectiveness in improving glucose tolerance in lean and obese mice over a dosing period of 15 days. The improvement in glucose tolerance was achieved at a dose less than that required to stimulate adipose tissue lipogenesis and which did not affect food intake or body weight.

British Journal of Pharmacology (1999) 128, 1586–1592; doi:10.1038/sj.bjp.0702946
Adverse effects of an active fragment of parathyroid hormone on rat hippocampal organotypic cultures
Authors: Hirasawa Takae , Nakamura Takeshi , Mizushima Akiko , Morita Mitsuhiro , Ezawa Ikuko , Miyakawa Hiroyoshi , Kudo Yoshihisa
Published: January 2005

Adverse effects of an active fragment of parathyroid hormone (PTH1–34), a blood Ca2+ level‐regulating hormone, were examined using rat hippocampal slices in organotypic culture.

Exposure of cultured slice preparations to 0.1 μM PTH1–34 for 60 min resulted in a gradual increase in the intracellular Ca2+ concentration ([Ca2+]i); this effect was most obvious in the apical dendritic region of CA1 subfield.

When PTH1–34 at a lower concentration (1 nM) was added to the culture medium and its toxic effects examined using a propidium iodide intercalation method, significant toxicity was seen 3 days after exposure and increased with time. Cells in the CA1 region seemed more vulnerable to the hormone than cells in other regions. At 1 week of exposure, the toxic effects were dose‐dependent over the range of 0.1 pM to 0.1 μM, the minimum effective dose being 10 pM.

The adverse effects were not induced either by the inactive fragment, PTH39–84, or by an active fragment of PTH‐related peptide (PTHrP1–34), an intrinsic ligand of the brain PTH receptor.

The PTH1–34‐induced adverse effects were significantly inhibited by co‐administration of 10 μM nifedipine, an L‐type Ca2+ channel blocker, but not by co‐administration of blockers of the other types of Ca2+ channel.

The present study demonstrates that sustained high levels of PTH in the brain might cause degeneration of specific brain regions due to Ca2+ overloading via activation of dihydropyridine‐sensitive Ca2+ channels, and suggests that PTH may be a risk factor for senile dementia.

British Journal of Pharmacology (2000) 129, 21–28; doi:10.1038/sj.bjp.0702949
Significant role of neuronal non‐N‐type calcium channels in the sympathetic neurogenic contraction of rat mesenteric artery
Authors: Tanaka Yoshio , Mochizuki Yumi , Tanaka Hikaru , Shigenobu Koki
Published: January 2005

The possible involvement of pre‐junctional non‐N‐type Ca2+ channels in noradrenaline (NA)‐mediated neurogenic contraction by electrical field stimulation (EFS) was examined pharmacomechanically in the isolated rat mesenteric artery.

EFS‐generated contraction of endothelium‐denuded mesenteric artery was frequency‐dependent (2–32 Hz) and was abolished by tetrodotoxin (TTX, 1 μM), guanethidine (5 μM) or prazosin (100 nM), indicating that NA released from sympathetic nerve endings mediates the contractile response.

NA‐mediated neurogenic contractions to lower frequency stimulations (2–8 Hz) were almost abolished by an N‐type Ca2+ channel blocker, ω‐conotoxin‐GVIA (1 μM) whereas the responses to higher frequency stimulations (12–32 Hz) were less sensitive to ω‐conotoxin‐GVIA. The ω‐conotoxin‐GVIA‐resistant component of the contractile response to 32 Hz stimulation was inhibited partly (10–20%) by ω‐agatoxin‐IVA (10–100 nM; concentrations which are relatively selective for P‐type channels) and to a greater extent by ω‐agatoxin‐IVA (1 μM) and ω‐conotoxin‐MVIIC (3 μM), both of which block Q‐type channels at the concentrations used.

ω‐Agatoxin‐IVA (10–100 nM) alone inhibited 32 Hz EFS‐induced contraction by 10∼20% whereas ω‐conotoxin‐MVIIC (3 μM) alone inhibited the response by ∼60%.

These ω‐toxin treatments did not affect the contractions evoked by exogenously applied NA.

These findings show that P‐ and Q‐type as well as N‐type Ca2+ channels are involved in the sympathetic neurogenic vascular contraction, and suggest the significant role of non‐N‐type Ca2+ channels in NA release from adrenergic nerve endings when higher frequency stimulations are applied to the nerve.

British Journal of Pharmacology (1999) 128, 1602–1608; doi:10.1038/sj.bjp.0702954
Levcromakalim causes indirect endothelial hyperpolarization via a myo‐endothelial pathway
Authors: Murai Takeshi , Muraki Katsuhiko , Imaizumi Yuji , Watanabe Minoru
Published: January 2005

Effects of K+ channel opener, levcromakalim, on vascular endothelial cells were examined. Under voltage‐ and current‐clamp conditions, application of acetylcholine to dispersed endothelial cells isolated from rabbit superior mesenteric artery (dispersed RMAECs) produced hyperpolarization and outward currents. On the other hand, dispersed RMAECs did not respond to levcromakalim.

When membrane potential was recorded from endothelium in a mesenteric arterial segment, exposure to levcromakalim in a concentration range of 0.1 to 3 μM caused concentration‐dependent hyperpolarization. The hyperpolarization was observed in the absence of external Ca2+ and was inhibited by 10 μM glibenclamide.

The presence of 1 mM heptanol did not affect the levcromakalin‐induced hyperpolarization, whereas treatment of the mesenteric arterial segment with 20 μM 18 β‐glycyrrhetinic acid significantly reduced the hyperpolarization. The response to acetylcholine of RMAECs in an arterial segment with 18 β‐glycyrrhetinic acid was, however, similar to that without 18 β‐glycyrrhetinic acid.

These suggest that although RMAECs themselves are functionally insensitive to levcromakalim, those in an arterial segment are hyperpolarized by levcromakalim via myo‐endothelial electrical communication.

British Journal of Pharmacology (1999) 128, 1491–1496; doi:10.1038/sj.bjp.0702956
Modulation of mPer1 gene expression by anxiolytic drugs in mouse cerebellum
Authors: Akiyama Masashi , Kirihara Tomoko , Takahashi Satomi , Minami Yoichi , Yoshinobu Yuko , Moriya Takahiro , Shibata Shigenobu
Published: January 2005

The mPer1 and mPer2 genes are putative mouse clock genes that regulate circadian oscillator present in the suprachiasmatic nucleus (SCN) neuron. While they are also expressed in the granular cell layer in the cerebellum, their function is unknown. In a first step to verify the physiological roles of mPer1 and mPer2 genes in the cerebellum, we examined the effects of benzodiazepines on the expression of the mPer1 and mPer2 genes.

mPer2 mRNA expression was higher at ZT16 than ZT4 in the mouse cerebellum.

High‐dose administration of diazepam (10 mg kg−1) or triazolam (1 mg kg−1) reduced mPer1 mRNA level 1 h after treatment in the cerebellum.

Reduced expression of mPer1 by diazepam treatment was transient. No difference of mPer1 mRNA level between diazepam (10 mg kg−1)‐ and vehicle‐treated group was observed 6 h after treatment.

Administration of high doses of tandospirone (30 mg kg−1), a non‐benzodiazepine anxiolytic also reduced mPer1 mRNA expression 1 h after treatment.

Administration of high doses of clozapine (5 mg kg−1) or haloperidol (1 mg kg−1) impaired the rota‐rod performance without affecting on mPer1 mRNA level.

Diazepam and tandospirone inhibited the expression of mPer1 mRNA in the primary cultured cerebellum granule cells.

Transient reductions of mPer1 mRNA levels by various benzodiazepines and tandospirone is associated with impairment of coordinated movement, such as rota‐rod performance and equilibrium.

British Journal of Pharmacology (1999) 128, 1616–1622; doi:10.1038/sj.bjp.0702957
Vascular kinin B1 and B2 receptor‐mediated effects in the rat isolated perfused kidney–differential regulations
Authors: Bagaté Karim , Develioglu Leyla , Imbs Jean‐Louis , Michel Bruno , Helwig Jean‐Jacques , Barthelmebs Mariette
Published: January 2005

Bradykinin (BK) and analogs acting preferentially at kinin B1 or B2 receptors were tested on the rat isolated perfused kidney. Kidneys were perfused in an open circuit with Tyrode's solution. Kidneys preconstricted with prostaglandin F2α were used for the analysis of vasodilator responses.

BK induced a concentration‐dependent renal relaxation (pD2=8.9±0.4); this vasodilator response was reproduced by a selective B2 receptor agonist, Tyr(Me)8‐BK (pD2=9.0±0.1) with a higher maximum effect (Emax=78.9±6.6 and 55.8±4.3% of ACh‐induced relaxation respectively, n=6 and 19, P<0.02). Icatibant (10 nM), a selective B2 receptor antagonist, abolished BK‐elicited relaxation. Tachyphylaxis of kinin B2 receptors appeared when repeatedly stimulated at 10 min intervals.

Des‐Arg9‐BK, a selective B1 receptor agonist, induced concentration‐dependent vasoconstriction at micromolar concentration. Maximum response was enhanced in the presence of lisinopril (1 μM) and inhibited by R 715 (8 μM), a selective B1 receptor antagonist. Des‐Arg9‐[Leu8]‐BK behaved as an agonist.

A contractile response to des‐Arg9‐BK occurred after 1 h of perfusion and increased with time by a factor of about three over a 3 h perfusion. This post‐isolation sensitization to des‐Arg9‐BK was abolished by dexamethasone (DEX, 30 mg kg−1 i.p., 3 h before the start of the experiment and 10 μM in perfusate) and actinomycin D (2 μM). Acute exposure to DEX (10 μM) had no effect on sensitized des‐Arg9‐BK response, in contrast to indomethacin (30 μM) that abolished it. DEX pretreatment however had no effect on BK‐induced renal vasodilation.

Present results indicate that the main renal vascular response to BK consists of relaxation linked to the activation of kinin B2 receptors which rapidly desensitize. Renal B1 receptors are also present and are time‐dependently sensitized during the in vitro perfusion of the rat kidneys.

British Journal of Pharmacology (1999) 128, 1643–1650; doi:10.1038/sj.bjp.0702961
Stereoselective central nervous system effects of the R‐ and S‐isomers of the GABA uptake blocker N‐(4,4‐di‐(3‐methylthien‐2‐yl)but‐3‐enyl) nipecotic acid in the rat
Authors: Cleton A , De Greef H J M M , Edelbroek P M , Voskuyl R A , Danhof M
Published: January 2005

The ‘effect compartment’ model was applied to characterize the pharmacodynamics of the R‐ and S‐isomers of tiagabine in conscious rats in vivo using increase in the β activity of the EEG as a pharmacodynamic endpoint.

No pharmacokinetic differences in plasma were observed between R‐ and S‐tiagabine. The values for clearance and volume of distribution at steady‐state were 103±10 versus 90±6 ml min−1 kg−1 and 1.8±0.2 versus 1.6±0.2 l kg−1 for the R‐ and S‐isomer, respectively. In contrast, plasma protein binding showed a statistically significant difference with values of the free fraction of 5.7±0.5 and 11.4±0.6%. In addition the rate constant for transport to the effect compartment was also different with values of 0.027 versus 0.067 min−1.

For both isomers the relationship between concentration and EEG effect was non‐linear and successfully characterized on basis of the Hill equation. A statistically significant difference in the value of EC50 of 328±11 versus 604±18 ng ml−1 was observed for R‐ and S‐tiagabine respectively. The values of the other pharmacodynamic parameters were identical.

It is concluded that the differences in in vivo pharmacodynamics of R‐ and S‐tiagabine can be explained by stereoselective differences in both the affinity to the GABA‐uptake transporter and the degree of non‐specific protein binding in plasma and at the effect site.

British Journal of Pharmacology (1999) 128, 1651–1658; doi:10.1038/sj.bjp.0702962
Selective cyclo‐oxygenase‐2 inhibitors aggravate ischaemia‐reperfusion injury in the rat stomach
Authors: Maricic Nenad , Ehrlich Karlheinz , Gretzer Britta , Schuligoi Rufina , Respondek Michael , Peskar Brigitta M
Published: January 2005

Effects of indomethacin, the selective cyclo‐oxygenase (COX)‐2 inhibitors NS‐398 and DFU, and dexamethasone on gastric damage induced by 30 min ischaemia followed by 60 min reperfusion (I‐R) were investigated in rats. Modulation of gastric levels of COX‐1 and COX‐2 mRNA by I‐R was evaluated using Northern blot and reverse transcription‐polymerase chain reaction.

I‐R‐induced gastric damage was dose‐dependently aggravated by administration of indomethacin (1–10 mg kg−1), NS‐398 (0.4–4 mg kg−1) or DFU (0.02–2 mg kg−1) as assessed macroscopically and histologically.

Likewise, administration of dexamethasone (1 mg kg−1) significantly increased I‐R damage.

Low doses of 16,16‐dimethyl‐prostaglandin(PG)E2, that did not protect against ethanol‐induced mucosal damage, reversed the effects of the selective COX‐2 inhibitors, indomethacin and dexamethasone.

I‐R had no effect on gastric COX‐1 mRNA levels but increased COX‐2 mRNA levels in a time‐dependent manner. Dexamethasone inhibited the I‐R‐induced expression of COX‐2 mRNA.

I‐R was not associated with a measurable increase in gastric mucosal formation of 6‐keto‐PGF1α and PGE2. PG formation was substantially inhibited by indomethacin (10 mg kg−1) but was not significantly reduced by NS‐398 (4 mg kg−1), DFU (2 mg kg−1) or dexamethasone (1 mg kg−1).

The findings indicate that selective COX‐2 inhibitors and dexamethasone markedly enhance gastric damage induced by I‐R. Thus, whereas COX‐2 has no essential role in the maintenance of gastric mucosal integrity under basal conditions, COX‐2 is rapidly induced in a pro‐ulcerogenic setting and contributes to mucosal defence by minimizing injury. This suggests that in certain situations selective COX‐2 inhibitors may have gastrotoxic effects.

British Journal of Pharmacology (1999) 128, 1659–1666; doi:10.1038/sj.bjp.0702966
Early intracellular signalling pathway of ethanol in vascular smooth muscle cells
Authors: Sachinidis Agapios , Gouni‐Berthold Ioanna , Seul Claudia , Seewald Stefan , Ko Yon , Schmitz Udo , Vetter Hans
Published: January 2005

ERKs belong to MAP kinase family and are activated by several growth and stress factors. Although ethanol has been shown to modulate ERK1 and ERK2 (p44mapk and p42mapk) activity, it can also act as an antiproliferative agent in various mammalian cells. Since the nature of the antiproliferative effect of ethanol in VSMCs has not been defined, we examined its effects on growth and on early intracellular events normally induced by growth factors in VSMCs.

Measurement of cytosolic Ca2+ and pH in cell monolayers was performed using fura‐2/AM and BCECF/AM, respectively. The effect of ethanol on VSMCs growth was assessed by [3H]‐thymidine incorporation, by cell counting and by determination of the caspase 3 activity. Stimulation of ERK1 and ERK2 was examined by the chemiluminescence Western blotting method. The expression of c‐fos was quantitated by Northern blotting. Determination of inositolphosphates was performed after labelling of VSMCs with myo‐[2‐3H]‐inositol and separation of inositolphosphates by HPLC.

Ethanol (0.3–1.0% v v−1, 17–170 mM) induced a dose‐dependent maximal stimulation of p44mapk/p42mapk at 30 min and expression of c‐fos mRNA with a maximum at 120 min. Intracellular events upstream to MAP kinase, like an increase in [Ca2+]i, activation of the Na+/H+ exchanger and formation of phosphoinositol metabolites were also markedly activated by ethanol. Treatment of VSMCs with ethanol for 3–5 min induced an increase in DNA synthesis whereas treatment of the cells for more than 30 min was toxic. Caspase 3 activity was not modulated by ethanol treatment of VSMCs.

We may postulate that the activation of these mitogenic signals including the elevation of DNA synthesis reflects a cell effort to protect itself against the toxic effects of ethanol.

British Journal of Pharmacology (1999) 128, 1761–1771; doi:10.1038/sj.bjp.0702969
Intracellular pH alterations induced by tacrine in a rat liver biliary epithelial cell line
Authors: Lagadic‐Gossmann D , Rissel M , Galisteo M , Guillouzo A
Published: January 2005

The effects of tacrine (THA) on intracellular pH (pHi) were examined in a rat liver biliary epithelial cell line (RLEC) in HEPES‐buffered medium. pHi was recorded using the pH‐sensitive fluoroprobe, carboxy‐SNARF‐1 (carboxy‐seminaphtorhodafluor).

In the steady state, short‐term exposures to THA resulted in alkalinization and re‐acidification at 0.1 and 0.25 mM. Following a 24 h‐treatment, no significant difference in pHi could be detected at 0.1 and 0.25 mM THA, whereas at 0.05 mM, pHi was slightly more acid (7.17±0.02, n=16 versus 7.21±0.02, n=24 [control]).

In control and short‐term treated cells, intracellular intrinsic buffering power (βi) increased roughly linearly as pHi decreased. This dependence was not seen following long‐term treatment. In all cases, βi was increased by THA (by 1.6 to 3.5 fold).

Following an acid load (induced by 20 mM NH4Cl removal), pHi recovery in RLEC relied upon Na+/H+ exchange. A short‐term treatment (0.25 mM THA) did not affect total acid extrusion. In contrast, a 24 h‐treatment with 0.05 mM THA reduced it (by ∼36% at a pHi of 6.73) while at 0.25 mM, a large increase was detected (by ∼109% at a pHi of 6.75).

In Na+‐free medium, THA (0.25 mM) still induced an alkalinization in the steady state. Following an acid load, THA stimulated a Na+‐independent acid efflux in a dose‐dependent manner, inhibitable by α‐cyano‐4‐hydroxy cinnamate (CHC, 4 mM) but not by quercetin (0.125 mM).

In conclusion, this work demonstrates that THA affects pHi in RLEC, through a decrease in Na+/H+ exchange and an increase in βi. Stimulation of a CHC‐inhibitable, Na+‐independent acid efflux is also detected.

British Journal of Pharmacology (1999) 128, 1673–1682; doi:10.1038/sj.bjp.0702972
Cardioprotection by the phytoestrogen genistein in experimental myocardial ischaemia‐reperfusion injury
Authors: Deodato Barbara , Altavilla Domenica , Squadrito Giovanni , Campo Giuseppe M , Arlotta Mariarita , Minutoli Letteria , Saitta Antonino , Cucinotta Domenico , Calapai Gioacchino , Caputi Achille P , Miano Maria , Squadrito Francesco
Published: January 2005

Soybean phytoestrogens have no oestrogen agonist effects on the reproductive system and therefore it is reasonable to explore the potential of these naturally occurring plant oestrogens in the cardiovascular pathology. We therefore investigated the effects of genistein in a rat model of myocardial ischaemia‐reperfusion injury.

Anaesthetized rats were subjected to total occlusion (45 min) of the left main coronary artery followed by 5 h reperfusion (MI/R). Sham operated rats were used as controls. Myocardial necrosis, myocardial myeloperoxidase activity (MPO), serum creatinine phosphokinase activity (CPK), serum and macrophage Tumour Necrosis Factor‐α (TNF‐α), cardiac intercellular adhesion molecule‐1 (ICAM‐1) immunostaining, cardiac mRNA for ICAM‐1 evaluated by the means of reverse transcriptase polymerase chain reaction (RT–PCR), ventricular arrhythmias and myocardial contractility (left ventricle dP/dtmax) were evaluated.

Myocardial ischaemia and reperfusion in untreated rats produced marked myocardial necrosis, increased serum CPK activity and MPO activity both in the area‐at‐risk and in the necrotic area, reduced myocardial contractility, caused ventricular arrhythmias and induced a marked increase in serum and macrophage TNF‐α. Furthermore myocardial ischaemia‐reperfusion injury increased ICAM‐1 expression in the myocardium.

Administration of genistein (1 mg kg−1, i.v., 5 min after coronary artery occlusion) lowered myocardial necrosis and MPO activity in the area‐at‐risk and in the necrotic area, decreased serum CPK activity, increased myocardial contractility, decreased the occurrence of ventricular arrhythmias, reduced serum and macrophages levels of TNF‐α and blunted ICAM‐1 expression in the injured myocardium. Finally genistein added in vitro to peritoneal macrophages collected from untreated rats subjected to myocardial ischaemia‐reperfusion injury significantly reduced TNF‐α production.

Our data suggest that genistein limits the inflammatory response and protects against myocardial ischaemia‐reperfusion injury.

British Journal of Pharmacology (1999) 128, 1683–1690; doi:10.1038/sj.bjp.0702973