bluuebunny/crossref_metadata_2025_split huggingface dataset:
The cholecystokinin analogues JMV‐180 and CCK‐8 stimulate phospholipase C through the same binding site of CCKA receptor in rat pancreatic acini
Authors: Sarri Elisabet , Ramos Belén , Salido Ginés M , Claro Enrique 
Published: January 2005

This study was designed to address the controversy related to the involvement of phospholipase C in the signalling pathway linked to CCKA receptor stimulation by the cholecystokinin analogue JMV‐180, a full agonist for amylase release, in rat pancreatic acini.
JMV‐180 was shown to stimulate phospholipase C by measuring the incorporation of [32P]‐orthophosphoric acid ([32P]‐Pi) into phosphatidic acid (PtdOH) and phosphatidylinositol (PtdIns). Both responses elicited by JMV‐180 were time and concentration dependent. Maximal effects elicited by JMV‐180 were 39.08±0.72 and 8.02±0.40% for the labelling of [32P]‐PtdIns and [32P]‐PtdOH, respectively, as compared to the maximal effects of CCK‐8, a full agonist of the CCKA receptor.
[32P]‐Pi incorporation into PtdOH and PtdIns was sensitive to lithium, demonstrating that both responses are a consequence of phospholipase C activation. However, since lithium blocks the phosphoinositide cycle by an uncompetitive mechanism, its effect was only apparent at high concentrations of CCK‐8 (>10 pM), which elicited stimuli above 20 and 60% of the maximal [32P]‐PtdOH and [32P]‐PtdIns labelling, respectively.
JMV‐180 inhibited the incorporation of [32P]‐Pi into PtdOH and PtdIns as stimulated by CCK‐8, down to its own maximal effect. The estimated IC50 values for the inhibition curves were not significantly different from those calculated assuming the same single binding site for both agonists. These results indicated that the well established role of JMV‐180 as a partial agonist for CCKA receptor‐linked signalling responses, also applies for the stimulation of phospholipase C.
The comparison of CCK‐8 and JMV‐180 dose‐response curves of amylase release to those of PtdIns and PtdOH labelling with [32P]‐Pi showed the existence of an amplification mechanism between phospholipase C and amylase release for both agonists.
In conclusion, we show that JMV‐180, as well as CCK‐8, stimulate phospholipase C upon interaction with the same binding site at the CCKA receptor in rat pancreatic acini.

British Journal of Pharmacology (2001) 133, 1227–1234; doi:10.1038/sj.bjp.0704190
Role of nitric oxide and superoxide in allergen‐induced airway hyperreactivity after the late asthmatic reaction in guinea‐pigs
Authors: Boer Jacob de , Meurs Herman , Flendrig Leonard , Koopal Miranda , Zaagsma Johan 
Published: January 2005

In the present study, the roles of nitric oxide (NO) and superoxide anions (O2−) in allergen‐induced airway hyperreactivity (AHR) after the late asthmatic reaction (LAR) were investigated ex vivo, by examining the effects of the NO synthase inhibitor Nω‐nitro‐L‐arginine methyl ester (L‐NAME) and superoxide dismutase (SOD) on the responsiveness to methacholine of isolated perfused guinea‐pig treacheae from unchallenged (control) animals and from animals 24 h after ovalbumin challenge.
At 24 h after allergen challenge, the animals developed AHR in vivo, as indicated by a mean 2.63±0.54 fold (P<0.05) increase in sensitivity to histamine inhalation.
Compared to unchallenged controls, tracheal preparations from the ovalbumin‐challenged guinea‐pigs displayed a significant 1.8 fold (P<0.01) increase in the maximal response (Emax) to methacholine, both after intraluminal (IL) and extraluminal (EL) administration of the agonist. No changes were observed in the sensitivity (pEC50) to the agonist. Consequently, the ΔpEC50 (EL‐IL), as a measure of epithelial integrity, was unchanged.
In the presence of L‐NAME (100 μM, IL), tracheae from control guinea‐pigs showed a 1.6 fold (P<0.05) increase in the Emax of IL methacholine. By contrast, the Emax of IL methacholine was significantly decreased in the presence of 100 u ml−1 EL SOD (54% of control, P<0.01).
Remarkably, the increased responsiveness to IL methacholine at 24 h after allergen challenge was reversed by L‐NAME to control (P<0.01), and a similar effect was observed with SOD (P<0.01).
The results indicate that both NO and O2− are involved in the tracheal hyperreactivity to methacholine after the LAR, possibly by promoting airway smooth muscle contraction through the formation of peroxynitrite.

British Journal of Pharmacology (2001) 133, 1235–1242; doi:10.1038/sj.bjp.0704191
Identification of the dopamine autoreceptor in the guinea‐pig retina as D2 receptor using novel subtype‐selective antagonists
Authors: Weber Bernd , Schlicker Eberhard , Sokoloff Pierre , Stark Holger 
Published: January 2005

Dopamine release in the retina is subject to modulation via autoreceptors, which belong to the D2 receptor family (encompassing the D2, D3 and D4 receptors). The aim of the present study was to determine the receptor subtype (D2 vs D3) involved in the inhibition of dopamine release in guinea‐pig retinal discs, using established (haloperidol, (S)‐nafadotride) and novel dopamine receptor antagonists (ST‐148, ST‐198).
hD2L and hD3 receptors were expressed in CHO cells and the pKi values determined in binding studies with [125I]‐iodosulpride were: haloperidol 9.22 vs 8.54; ST‐148 7.85 vs 6.60; (S)‐nafadotride 8.52 vs 9.51; ST‐198 6.14 vs 7.92.
The electrically evoked tritium overflow from retinal discs preincubated with [3H]‐noradrenaline (which represents quasi‐physiological dopamine release) was inhibited by the dopamine receptor agonists B‐HT 920 (talipexole) and quinpirole (maximally by 82 and 71%; pEC50 5.80 and 5.83). The concentration‐response curves of these agonists were shifted to the right by haloperidol (apparent pA2 8.69 and 8.23) and ST‐148 (7.52 and 7.66). (S)‐Nafadotride 0.01 μM and ST‐198 0.32 μM did not affect the concentration‐response curve of B‐HT 920.
The dopamine autoreceptor in the guinea‐pig retina can be classified as a D2 receptor. ST‐148 and ST‐198 show an improved selectivity for D2 and D3 receptors when compared to haloperidol and (S)‐nafadotride, respectively.

British Journal of Pharmacology (2001) 133, 1243–1248; doi:10.1038/sj.bjp.0704192
Human colonic anti‐secretory activity of the potent NK1 antagonist, SR140333: assessment of potential anti‐diarrhoeal activity in food allergy and inflammatory bowel disease
Authors: Moriarty Derek , Goldhill Jon , Selve Norma , O'Donoghue Diarmuid P , Baird Alan W 
Published: January 2005

This in vitro study was designed to determine the potential use of the NK1 antagonist, SR140333 as an anti‐diarrhoeal treatment for food allergy or inflammatory bowel disease. The effect of various immune and neuronal stimuli on human colonic substance P (SP) release and the effect of SR140333 on subsequently stimulated mucosal ion transport was investigated.
Submucosal and sensory nerve fibre stimulation using electrical field stimulation (1 ms/7 Hz/7 V) and capsaicin (50 μM) respectively, mast cell activation by anti‐IgE (1/250 dilution) and granulocyte stimulation using fMLP (50 μM) each released SP and evoked a secretory response.
SP and the NK1 selective agonist, Sar‐SP (0.1–1000 nM) stimulated an increase in colonic secretion which was antagonized by SR140333 (pD′2=6.7 and 7.25 versus SP and Sar‐SP respectively).
SR140333, at a concentration that blocked NK1‐mediated secretion (500 nM), also reduced the secretory response to both αIgE and capsaicin. This suggests a pathophysiologic role for NK1 receptors.
Capsaicin evoked SP release was increased in tissue taken from Crohn's disease but not ulcerative colitis patients. The response to SP was however reduced by 70 and 89% respectively.
Mast cells and sensory afferents contribute to allergic diarrhoea. Since SR140333 reduced the secretory response to mast cell and afferent stimulation this compound may be particularly useful in reducing the symptoms of food allergy.

British Journal of Pharmacology (2001) 133, 1346–1354; doi:10.1038/sj.bjp.0704194
Mutational analysis of the human vasoactive intestinal peptide receptor subtype VPAC2: role of basic residues in the second transmembrane helix
Authors: Vertongen P , Solano R M , Perret J , Langer I , Robberecht P , Waelbroeck M 
Published: January 2005

We investigated the role of two conserved basic residues in the second transmembrane helix arginine 172 (R172) and lysine 179 (K179) of the VPAC2 receptor.
Vasoactive intestinal polypeptide (VIP) activated VPAC2 receptors with an EC50 value of 7 nM, as compared to 150, 190 and 4000 nM at R172L, R172Q and K179Q‐VPAC2 receptors, respectively. It was inactive at K179I mutated VPAC2 receptors. These results suggested that both basic residues were probably implicated in receptor recognition and activation.
The VPAC2‐selective VIP analogue, [hexanoyl‐His1]‐VIP (C6‐VIP), had a higher affinity and efficacy as compared to VIP at the mutated receptors.
VIP, Asn3‐VIP and Gln3‐VIP activated adenylate cyclase through R172Q receptors with EC50 values of 190, 2 and 2 nM, respectively, and through R172L receptors with EC50 values of 150, 12 and 8 nM, respectively. Asn3‐VIP and Gln3‐VIP behaved as partial agonists at the wild type receptor, with Emax values (in per cent of VIP) of 75 and 52%, respectively. In contrast, they were more efficient than VIP (Emax values of 150 and 150% at the R172Q VPAC2 receptors, and of 400 and 360% at the R172L receptors, respectively). These results suggested that the receptor's R172 and the ligand's aspartate 3 are brought in close proximity in the active ligand‐receptor complex.
The K179I and K179Q mutated receptors had a lower affinity than the wild‐type receptors for all the agonists tested in this work: we were unable to identify the VIP amino acid(s) that interact with K179.

British Journal of Pharmacology (2001) 133, 1249–1254; doi:10.1038/sj.bjp.0704195
Diazepam increases the hypothalamic‐pituitary‐adrenocortical (HPA) axis activity by a cyclic AMP‐dependent mechanism
Authors: Vargas M Luisa , Abella Cristina , Hernandez Jesus 
Published: January 2005

Previous studies in this laboratory have shown that diazepam behaves as a phosphodiesterase 4 (PDE 4) inhibitor. It has been reported that PDE‐4 inhibitors activate the hypothalamic‐pituitary‐adrenocortical (HPA) axis in the rat. In the present study we have examined whether activation of the cyclic AMP‐dependent protein kinase (PKA) is involved in the effect of diazepam on basal HPA axis activity.
Acute systemic administration of diazepam (10 mg kg−1 i.p.) was found to increase the basal HPA axis activity, increasing the plasma concentrations of corticotrophin (ACTH) and corticosterone 30 min post injection. Diazepam also elevated cyclic AMP content of the hypothalamus.
Pretreatment of the animals with dexamethasone (1 mg kg−1 s.c.) for 3 days completely abolished the effect of diazepam on HPA axis activity.
The antagonists of central and peripheral benzodiazepine receptors, flumazenil (10 mg kg−1 i.p.) and PK 11195 (5 mg kg−1 i.p.) did not affect the diazepam induced increase of HPA axis activity nor did they have an effect per se.
The increase in ACTH and corticosterone levels was significantly reduced by the cyclic AMP‐dependent protein kinase (PKA) inhibitor, H‐89, given either subcutaneously (5 mg kg−1 s.c.) or intracerebroventricularly (i.c.v.; 28 μg in 10 μl).
The results indicate that diazepam can stimulate basal HPA axis activity in the rat by a cyclic AMP‐dependent PKA mediated pathway.

British Journal of Pharmacology (2001) 133, 1355–1361; doi:10.1038/sj.bjp.0704201
Effects of the novel selective endothelin ETA receptor antagonist, SB 234551, on the cardiovascular responses to endotoxaemia in conscious rats
Authors: Gardiner S M , March J E , Kemp P A , Bennett T 
Published: January 2005

In conscious, freely moving, male, Long Evans rats, regional haemodynamic responses to exogenous endothelin‐1 (ET‐1; 25, 50 and 250 pmol kg−1 i.v.) were assessed in the presence of vehicle, or the selective ETA‐receptor antagonist, SB 234551. On the following day, the effects of SB 234551 on the haemodynamic responses to lipopolysaccharide (LPS) infusion (150 μg kg−1 h−1, i.v.) were determined.
When SB 234551 was given i.v. by primed infusion at a dose of 0.3 mg kg−1 bolus, 0.3 mg kg−1 h−1 infusion, it caused selective inhibition of the vasoconstrictor effects of exogenous endothelin‐1, whereas at a dose of 1 mg kg−1, 1 mg kg−1 h−1, SB 234551 also inhibited some of the vasodilator effects of endothelin‐1.
Infusion of LPS, in the presence of vehicle, caused a short‐lived (1–2 h) hypotension, tachycardia, and vasodilatation in renal, superior mesenteric and hindquarters vascular beds. Thereafter, blood pressure, heart rate and mesenteric vascular conductance returned to baseline values, but renal vasodilatation persisted, and there was vasoconstriction in the hindquarters.
In the presence of SB 234551 (0.3 mg kg−1, 0.3 mg kg−1 h−1), the early (1–2 h) cardiovascular responses to LPS infusion were unaffected, but the subsequent recovery of mean arterial blood pressure was impaired, due to developing vasodilatation in the mesenteric and, to a lesser extent, hindquarters, vascular beds. SB 234551 had no effect on the renal haemodynamic responses to LPS infusion.
The results confirm an important, regionally‐selective, vasoconstrictor role for endogenous endothelin in this model of endotoxaemia.

British Journal of Pharmacology (2001) 133, 1371–1377; doi:10.1038/sj.bjp.0704202
Mechanism of trypsin‐induced contraction in the rat myometrium: the possible involvement of a novel member of protease‐activated receptor
Authors: Shintani Yoshinobu , Hirano Katsuya , Nakayama Tetsuzo , Nishimura Junji , Nakano Hitoo , Kanaide Hideo 
Published: January 2005

The mechanism of trypsin‐induced contraction in the rat myometrium was investigated using front‐surface fluorimetry on fura‐PE3‐loaded strips. The expression of protease‐activated receptors (PARs) in the rat myometrium was determined by reverse transcription polymerase chain reaction (RT–PCR).
In non‐pregnant rats, 10 μM trypsin developed a force of up to 30.5±5.1% of that obtained during the 40 mM K+‐depolarization‐induced contraction. In pregnant rats, the maximal level of the cytosolic Ca2+ concentration and tension obtained with 3 μM trypsin was 143.2±6.0% and 63.2±7.9%, respectively. The depletion of the extracellular Ca2+ abolished the trypsin‐induced contraction.
Trypsin‐induced contraction was abolished by the pre‐treatment of a serine protease inhibitor. PAR1‐activating peptide (PAR1‐AP) caused a potent contraction of the myometrium, while neither PAR2‐AP nor PAR4‐AP induced any contraction.
RT–PCR analysis detected the expression of PAR1 mRNA. However, neither PAR2 nor PAR4 mRNA was detected in the rat myometrium.
Once the strips were stimulated with thrombin, the subsequent application of thrombin failed to induce any contraction, while trypsin induced a contraction similar to that observed without the pre‐stimulation with thrombin. Once the strip was stimulated with trypsin, neither trypsin nor thrombin induced any contraction. The response to PAR1‐AP remained after the pre‐stimulation with thrombin and trypsin.
In conclusion, PAR1 was the only known receptor for trypsin expressed in the rat myometrium, but it was suggested to be cleaved and inactivated by trypsin. Trypsin was thus suggested to contract the rat myometrium via a novel type of PAR, which might be upregulated during pregnancy.

British Journal of Pharmacology (2001) 133, 1276–1285; doi:10.1038/sj.bjp.0704206
Evidence that the anti‐spasmogenic effect of the β‐adrenoceptor agonist, isoprenaline, on guinea‐pig trachealis is not mediated by cyclic AMP‐dependent protein kinase
Authors: Spicuzza Lucia , Belvisi Maria G , Birrell Mark A , Barnes Peter J , Hele David J , Giembycz Mark A 
Published: January 2005

The spasmolytic and anti‐spasmogenic activity of β‐adrenoceptor agonists on airways smooth muscle is thought to involve activation of the cyclic AMP/cyclic AMP‐dependent protein kinase (PKA) cascade. Here we have tested the hypothesis that PKA mediates the anti‐spasmogenic activity of isoprenaline and other cyclic AMP‐elevating agents in guinea‐pig isolated trachea by utilizing a number of cell permeant cyclic AMP analogues that act as competitive ‘antagonists’ of PKA.
Anion‐exchange chromatography of guinea‐pig tracheae resolved two peaks of PKA activity that corresponded to the type I (∼5%) and type II (∼93%) isoenzymes.
Pre‐treatment of tracheae with zardaverine (30 μM), vasoactive intestinal peptide (VIP) (1 μM) and the non‐selective activator of PKA, Sp‐8‐CPT‐cAMPS (10 μM), produced a non‐parallel rightwards shift in the concentration‐response curves that described acetylcholine (ACh)‐induced tension generation. The type II‐selective PKA inhibitor, Rp‐8‐CPT‐cAMPS (300 μM), abolished this effect.
Pre‐treatment of tracheae with Sp‐8‐Br‐PET‐cGMPS (30 μM) produced a non‐parallel rightwards shift of the concentration‐response curves that described ACh‐induced tension generation. The selective cyclic GMP‐dependent protein kinase (PKG) inhibitor, Rp‐8‐pCPT‐cGMPS (300 μM), abolished this effect.
Pre‐treatment of tracheae with isoprenaline (1 μM) produced a 10 fold shift to the right of the ACh concentration‐response curve by a mechanism that was unaffected by Rp‐8‐Br‐cAMPS (300 μM, selective inhibitor of type I PKA), Rp‐8‐CPT‐cAMPS (300 μM) and Rp‐8‐pCPT‐cGMPS (300 μM).
We conclude that the anti‐spasmogenic activity of Sp‐8‐CPT‐cAMPS, zardaverine and VIP in guinea‐pig trachea is attributable to activation of the cyclic AMP/PKA cascade whereas isoprenaline suppresses ACh‐induced contractions by a mechanism(s) that is independent of PKA and PKG.

British Journal of Pharmacology (2001) 133, 1201–1212; doi:10.1038/sj.bjp.0704213
A novel tachykinin NK2 receptor antagonist prevents motility‐stimulating effects of neurokinin A in small intestine
Authors: Lördal Mikael , Navalesi Giovanni , Theodorsson Elvar , Maggi Carlo A , Hellström Per M 
Published: January 2005

MEN 11420 (nepadutant) is a potent, selective and competitive antagonist of tachykinin NK2 receptors.
The objective of the present study was to assess the capability of the drug to antagonize the stimulatory effects of neurokinin A (NKA) on gastrointestinal motility, as well as to change the fasting migrating motor complex (MMC).
Thirty‐four male volunteers were randomized to treatment with either placebo or MEN 11420 in a double‐blinded manner. Effects of MEN 11420 (8 mg intravenously) were evaluated as changes in phases I, II and III of MMC, as well as contraction frequency, amplitude and motility index during baseline conditions and during stimulation of motility using NKA (25 pmol kg−1 min−1 intravenously).
NKA preceded by placebo increased the fraction of time occupied by phase II, increased contraction frequency, amplitude and motility index.
MEN 11420 effectively antagonized the motility‐stimulating effects of NKA. MEN 11420 reduced the phase II‐stimulating effect of NKA. In addition, the stimulatory effect of NKA on contraction frequency and amplitude, as well as motility index were inhibited by MEN 11420. MEN 11420 did not affect the characteristics of MMC during saline infusion.
Plasma levels of MEN 11420 peaked during the first hour after infusion and decreased to less than half during the first 2 h.
In conclusion, intravenous MEN 11420 effectively inhibited NKA‐stimulated, but not basal gastrointestinal motility, and was well tolerated by all subjects.

British Journal of Pharmacology (2001) 134, 215–223; doi:10.1038/sj.bjp.0704217
Effects of ACE inhibition and angiotensin II type 1 receptor blockade on cardiac function and G proteins in rats with chronic heart failure
Authors: Yoshida Hiroyuki , Takahashi Masaya , Tanonaka Kouichi , Maki Toshiyuki , Nasa Yoshihisa , Takeo Satoshi 
Published: January 2005

Inhibition of the renin‐angiotensin system (RAS) improves symptoms and prognosis in heart failure. The experimental basis for these benefits remains unclear. We examined the effects of inhibition of ACE or blockade of angiotensin II type 1 (AT1) receptor on the haemodynamics, cardiac G‐proteins, and collagen synthesis of rats with coronary artery ligation (CAL), a model in which chronic heart failure (CHF) is induced.
Rats were orally treated with the ACE inhibitor trandolapril (3 mg kg−1 day−1) or the AT1 receptor blocker L‐158809 (1 mg kg−1 day−1) from the 2nd to 8th week after CAL. CAL resulted in decreases in the left ventricular systolic pressure and its positive and negative dP/dt, an increase in the left ventricular end‐diastolic pressure, and the rightward shift of the left ventricular pressure‐volume curve. Long‐term treatment with either drug improved these signs of CHF to a similar degree.
Cardiac Gsα and Gqα protein levels decreased, whereas the level of Giα protein increased in the animals with CHF. Long‐term treatment with trandolapril or L‐158809 attenuated the increase in the level of cardiac Giα protein of the animals with CHF without affecting Gsα and Gqα protein levels. Cardiac collagen content of the failing heart increased, whose increase was blocked by treatment with either drug.
Exogenous angiotensin I stimulated collagen synthesis in cultured cardiac fibroblasts, whose stimulation was attenuated by either drug.
These results suggest that blockade of the RAS, at either the receptor level or the synthetic enzyme level, may attenuate the cardiac fibrosis that occurs after CAL and thus affect the remodelling of the failing heart.

British Journal of Pharmacology (2001) 134, 150–160; doi:10.1038/sj.bjp.0704219
NO‐induced relaxation of labouring and non‐labouring human myometrium is not mediated by cyclic GMP
Authors: Buxton Iain L O , Kaiser Robert A , Malmquist Nicholas A , Tichenor Stephen 
Published: January 2005

In myometrial strips from near‐term non‐labouring human uterus, addition of oxytocin (OT) evoked dose‐dependent (10 – 3000 nM) phasic contractions that were antagonized by atosiban (1 μM) and relaxed by addition of the nitric oxide donor S‐nitroso L‐cysteine (Cys‐NO). In near‐term labouring myometrium, however, addition of OT was ineffective at raising additional tone.
In both labouring and non‐labouring tissue, Cys‐NO mediated relaxation of spontaneous or OT‐induced contractions (IC50=1 μM) was unaffected by prior addition of the guanylyl cyclase (GC) inhibitors ODQ (1H‐[1,2,4]oxadiazolo[4,3,‐α]quinoxalin‐1‐one; 1 μM), or methylene blue (MB; 10 μM).
Elevation of intracellular cyclic GMP accompanying 30 μM Cys‐NO addition in non‐labouring tissue (7.5 fold) or in labouring tissues (2.5 fold) was completely blocked in tissues that had been pre‐treated with ODQ or MB.
Charybdotoxin (ChTx), iberiotoxin (IbTx) and kaliotoxin (KalTx) all shifted the Cys‐NO inhibition curve to the right and reduced the degree of relaxation produced by maximal Cys‐NO treatment (100 μM in non‐labouring tissue; in labouring tissue, KalTx prevented Cys‐NO mediated relaxation in both stimulated and unstimulated tissue.
Addition of the NO‐donor S‐nitroso N‐acetyl penicillamine (SNAP) produced a dose‐dependent relaxation of pregnant myometrium while 3‐morpholinosyndonimine (SIN‐1) did not. The failure of SIN‐1 to relax OT‐induced contractions was not due to a failure of the donor to stimulate myometrial GC.
We demonstrate that despite the ability of NO to stimulate myometrial GC in pregnant uterine muscle, relaxations are independent of cyclic GMP action. Effects of K+‐channel inhibitors suggests that NO‐induced relaxation in human uterine smooth muscle may be subserved by direct or indirect activation of one or more calcium‐activated K+‐channels.

British Journal of Pharmacology (2001) 134, 206–214; doi:10.1038/sj.bjp.0704226