bluuebunny/crossref_metadata_2025_split huggingface dataset:
Competitive inhibition by procaine of carbachol‐induced stimulus‐secretion coupling in rat pancreatic acini
Authors: Ikei Nobuhiro , Busik Julia , Habara Yoshiaki , Kanno Tomio 
Published: July 2012

Procaine (0.03–10 mm) inhibited carbacbol (CCh)‐induced amylase release from rat isolated pancreatic acini in a competitive manner. Kinetic analysis of the relation between CCh concentrations and the amount of amylase released in the presence of various procaine concentrations indicated that procaine caused competitive inhibition with the affinity constant (pA2) value of 5.00 ± 0.08.
Receptor binding assay confirmed that procaine (0.01–10 mm) competitively inhibited [N‐methyl‐3H]‐scopolamine chloride ([3H]‐NMS) binding to its receptor with binding affinity (pKi) of 4.63 ± 0.10.
Procaine transformed CCh‐evoked [Ca2+]i dynamics: the initial rise in [Ca2+]i followed by a gradual decay during continuous stimulation with 3 μm CCh was transformed by 0.3 mm procaine to the oscillatory [Ca2+]i dynamics, which resembled the response to 0.3 μm CCh in the absence of procaine. The initial phase of [Ca2+]i oscillation corresponded to the initial phase of CCh‐induced amylase release in isolated perfused acini.
Procaine (0.3–3 mm) did not inhibit the secretory response to cholecystokinin octapeptide (CCK‐8) in isolated incubated acini. A higher concentration of procaine (10 mm) caused weak but significant inhibition of the response to only limited concentrations of CCK‐8, 30 and 100 pm. Procaine lower than 10 mm was ineffective on [125I]‐BH‐CCK‐8 binding, although procaine (10 mm) caused weak but significant inhibition of the binding.
Salmeterol, a long‐acting β2‐adrenoceptor agonist mediating cyclic AMP accumulation in a neuronal cell line
Authors: McCrea Karen E. , Hill Stephen J. 
Published: July 2012

The accumulation of cyclic AMP stimulated by salmeterol, a long‐acting β2‐adrenoceptor agonist and by isoprenaline, a non‐selective β‐adrenoceptor agonist have been compared in the B50 neuroblastoma cell line.
Salmeterol produced a concentration‐dependent increase in the accumulation of total [3H]‐cyclic AMP in B50 cells yielding an EC50 value of 37 nm which was lower than that obtained with isoprenaline (294 nm). The maximum response to salmeterol was only 46% of that obtained with isoprenaline.
The β2‐adrenoceptor antagonist, ICI 118551, inhibited the responses to both salmeterol (apparent KD 2.2 nm) and isoprenaline (apparent KD 1.6 nm). However, the β1‐adrenoceptor antagonist, atenolol, produced no significant effect at concentrations up to 100 μm.
Salmeterol (1 μm) changed the concentration‐response curve of isoprenaline in the manner of a partial agonist interacting with a full agonist. The KD of salmeterol obtained from the interaction was 55.6 nm.
Whereas salmeterol has a slow onset of action in airway smooth muscle compared to other β2‐adrenoceptor agonists, in B50 monolayers both salmeterol and isoprenaline produced a rapid increase in cyclic AMP accumulation (t1/2 1.1 min and 0.4 min respectively).
Despite the existence of cyclic AMP efflux mechanisms that exist in this cell line it was possible to investigate the duration of agonist action by measuring intracellular levels of the second messenger. Replacement of drug‐containing medium with fresh buffer led to a rapid reduction in intracellular levels of cyclic AMP in isoprenaline‐stimulated cells whereas cyclic AMP accumulation was sustained for much longer periods in salmeterol‐stimulated cells. However, the persistent action of salmeterol could be reversed by the addition of a β2‐selective antagonist.
These results confirm that salmeterol has a high affinity, but low efficacy (relative to isoprenaline) for β2‐adrenoceptors coupled to cyclic AMP accumulation and that the drug persists at its site of action for long periods in the B50 neuronal cell line.
Bradykinin‐induced airflow obstruction and airway plasma exudation: effects of drugs that inhibit acetylcholine, thromboxane A2 or leukotrienes
Authors: Kawikova Ivana , Arakawa Hirokazu , Löfdahl Claes‐Göran , Skoogh Bengt‐Eric , Lötvall Jan 
Published: July 2012

The mechanisms behind bradykinin‐induced effects in the airways are considered to be largely indirect. The role of cholinergic nerves and eicosanoids, and their relationship in these mechanisms were investigated in guinea‐pigs.
The role of cholinergic nerves was studied in animals given atropine (1 mg kg−1, i.v.), hexamethonium (2 mg kg−1, i.v.), or vagotomized. To study the role of eicosanoids, animals were pretreated with a thromboxane A2 (TxA2) receptor antagonist (ICI 192,605; 10−6 mol kg−1, i.v.) or with a leukotriene (LT) receptor C4/D4/E4 antagonist (ICI 198,615; 10−6 mol kg−1, i.v.).
After pretreatment with a drug, bradykinin (150 nmol) was instilled into the tracheal lumen. We measured both airway insufflation pressure (Pi), to assess airway narrowing, and the content of Evans blue dye in airway tissue, to assess plasma exudation.
Bradykinin instillation into the trachea caused an increase in Pi and extravasation of Evans blue dye. The increase in Pi was significantly attenuated by atropine or the TxA2 receptor antagonist, but not by hexamethonium, vagotomy or the LT receptor antagonist.
The bradykinin‐induced exudation of Evans blue dye was significantly attenuated in the intrapulmonary airways by the TxA2 receptor antagonist, but not by atropine, hexamethonium, cervical vagotomy or the LT receptor antagonist.
A thromboxane‐mimetic, U‐46619 (20 nmol kg−1, i.v. or 10 nmol intratracheally), caused both an increase in Pi and extravasation of Evans blue dye at all airway levels. Atropine pretreatment slightly attenuated the peak Pi after the intratracheal administration of U‐46619, but not after i.v. administration.
We conclude that peripheral cholinergic nerves are involved in bradykinin‐induced airflow obstruction but not plasma exudation, and that TxA2 is involved in both airflow obstruction and airway plasma exudation induced by bradykinin given via the airway route. TxA2‐induced airflow obstruction is mediated only to a minor degree, via the release of acetylcholine in the airways.
An electrophysiological investigation of the properties of 5‐HT3 receptors of rabbit nodose ganglion neurones in culture
Authors: Peters John A. , Malone Hilary M. , Lambert Jeremy J. 
Published: July 2012

The biophysical and pharmacological properties of 5‐hydroxytryptamine (5‐HT)‐evoked currents in rabbit nodose ganglion neurones in culture have been determined by use of the whole‐cell and outside‐out membrane patch recording modes of the patch‐clamp technique.
In 49% of cells investigated the bath application of 10−5 m 5‐HT at negative holding potentials elicited an inward current. The whole‐cell response to 5‐HT reversed in sign (E5‐HT) at approximately − 2 mV and exhibited inward rectification.
The influence of various ion substitutions upon E5‐HT established that the 5‐HT‐evoked current is mainly mediated by a mixed Na+, K+ cation conductance with little or no contribution from Cl− ions. The omission of Ca2+ and Mg2+ from the extracellular solution enhanced the amplitude of the 5‐HT‐induced current.
On isolated outside‐out membrane patches, the bath application of 10−6 m 5‐HT induced single channel currents with a chord conductance of approximately 17 pS at − 70 mV and an average slope conductance of 19 pS over the range − 100 to − 40 mV. The 5‐HT‐induced single channels exhibited modest inward rectification and were reduced in frequency, but not amplitude, by the 5‐HT3 receptor antagonist metoclopromide (10−6 m).
The bath application of 5‐HT (3 × 10−7 − 3 × 10−5 m) to whole cells voltage clamped at − 60 mV produced dose‐dependent inward currents which were mimicked by 2‐methyl‐5‐HT and 1‐phenylbiguanide with equipotent molar ratios, relative to 5‐HT, of 2.5 and 32 respectively.
Whole‐cell inward currents produced by the local pressure application of 5‐HT (10−5 m) were unaffected by 10−6 m methysergide, 10−6 m ketanserin or 10−6 m citalopram, but were concentration‐dependently antagonized by the selective 5‐HT3 receptor antagonists tropisetron (IC50 = 4.6 × 10−11 m) ondansetron (IC50 = 5.7 × 10−11 m), and bemesetron (IC50 = 3.3 × 10−10 m). The response to 5‐HT was also blocked by the non‐selective antagonists metoclopramide (IC50 = 1.2 × 10−8 m), cocaine (IC50 = 8.3 × 10−8 m) and (+)‐tubocurarine (IC50 = 1.6 × 10−7 m).
Differential affinity of dihydroimidazoquinoxalines and diimidazoquinazolines to the α1β2γ2 and α6β2γ2 subtypes of cloned GABAA receptors
Authors: Im Wha Bin , Im Haesook K. , Pregenzer Jeffrey F. , Hamilton Beverly J. , Carter Donald B. , Jacobsen E. Jon , TenBrink Ruth E. , VonVoigtlander Philip F. 
Published: July 2012

In this study, we compared two series of newly discovered ligands for their selectivity to benzodiazepine sites in the α1β2γ2 and the α6β2γ2 subtypes of cloned γ‐aminbutyric acidA (GABAA) receptors, the latter being unique in not interacting with classical benzodiazepines.
The prototype compounds, U‐85575 (12‐chloro‐5‐(5‐cyclopropyl‐1′,2′,4′‐oxadiazol‐3′‐yl)‐2,3‐dihydro‐diimidazo[1,5‐a;1,2‐c]quinazoline), and U‐92330 (5‐acetyl‐3‐(5′‐cyclopropyl‐1′,2′,4′‐oxadiazole‐3′‐yl)‐7‐chloro‐4,5‐dihydro[1,5‐a]quinoxaliné), appear to share an overlapping recognition site with classical benzodiazepines on the GABAA receptor, because their potentiation of GABA‐mediated Cl− currents in both subtypes were sensitive to Ro 15–1788, a classical benzodiazepine antagonist.
Minor changes in the ring substituents of the drugs reduced their affinity to the α6β2γ2 subtype more pronouncedly than to the α1β2γ2 subtype. The diimidazoquinazoline containing a 2‐methyl group which projected below the plane of the rigid ring showed a markedly lower affinity to the α6β2γ2 subtype as compared to its stereoisomer having the methyl group above the plane of the ring. Also, the dihydroimidazoquinoxalines containing the 5‐benzoyl group showed a lower affinity to the α6β2γ2 subtype than the 5‐acetyl counterpart. In particular, the 5‐benzoyl analogue containing a 6‐fluoro group showed no interaction with the α6β2γ2 subtype even at the concentration of 10 μm, probably due to stabilization of the benzoyl group in the out‐of‐plane region by the steric and electrostatic effects of the 6‐fluoro group.
We propose that the benzodiazepine site of the α6β2γ2 subtype shares overlapping regions with that of the α1β2γ2 subtype, but has a sterically restricted out‐of‐plane region, which may be also incompatible with the 5‐phenyl group of classical benzodiazepines.
Ionomycin‐induced acetylcholine release and its inhibition by adenosine at frog motor nerve endings
Authors: Hunt Jarnes M. , Silinsky Eugene M. 
Published: July 2012

Acetylcholine (ACh) evoked secretion by the calcium ionophore, ionomycin, was studied at frog motor nerve endings.
Bath application of ionomycin stimulated an irreversible increase in the rate of spontaneous, quantal ACh release in the presence of extracellular Ca2+. In contrast, local application of ionomycin stimulated a rapid, reversible acceleration of spontaneous ACh release.
The magnitude of the secretory response to ionomycin was dependent both upon the concentration of ionophore and the concentration of extracellular Ca2+.
Adenosine or 2‐chloroadenosine inhibited ionomycin‐stimulated ACh release with the same potency and efficacy observed previously for these adenosine analogues as inhibitors of ACh secretion evoked by nerve impulses.
These results support the conclusion that adenosine receptor activation inhibits quantal ACh secretion at a site distal to that of Ca2+ entry at frog motor nerve endings.
Stimulated eosinophils and proteinases augment the transepithelial flux of albumin in bovine bronchial mucosa
Authors: Herbert Carolyn A. , Edwards David , Boot John R. , Robinson Clive 
Published: July 2012

The apical to basolateral transmucosal flux of albumin has been measured in isolated sheets of bovine bronchial and tracheal mucosa. Under resting conditions the net unidirectional flux in the bronchial mucosa was not significantly different from that measured previously for the basolateral to apical vector. In contrast, the apical to basolateral flux in the tracheal mucosa was significantly lower than that measured in the opposite direction.
Addition of guinea‐pig peritoneal eosinophils to the apical side of the tissues had no significant effect on the transmucosal flux of albumin in either the bronchial or tracheal mucosa.
When eosinophils were stimulated with the ionophore A23187 or by opsonic adherence to tissues treated with a guinea‐pig anti‐bovine airway epithelium antibody, the bronchial mucosal sheets that had been exposed showed a significant increase in the transmucosal flux of albumin. However, tissues from the tracheal mucosa were resistant to the effects of stimulated eosinophils.
Histologically, sheets of mucosa from bovine main bronchi that had been exposed to stimulated eosinophils were characterized by epithelial injury consisting of loss of columnar epithelium from the underlying basal cell layer and biomatrix. Much less evidence of cellular injury was observed in tracheal tissues.
Bacterial collagenases applied to the apical side of the sheets were shown to increase the permeability of the bronchial mucosa to albumin and to produce histological changes that had similarities with the pattern of damage produced by stimulated eosinophils.
These observations demonstrate that the ability of eosinophils to injure the bronchial mucosa is independent of the side of the tissue on which they are present. Furthermore, key aspects of the injury process may be reproduced, at least in part, by metalloproteinases.
Characterization of the adenosine receptors of the rat superior cervical ganglion
Authors: Connolly G.P. , Stone T.W. , Brown F. 
Published: July 2012

Adenosine analogues caused hyperpolarization and inhibition of the depolarizing response to muscarine of the rat isolated superior cervical ganglion (SCG) measured by a ‘grease gap’ recording technique. The receptors mediating these responses have been characterized by use of a range of selective adenosine analogues and adenosine receptor antagonists.
In decreasing order of potency N6‐cyclopentyladenosine (CPA), 2‐chloroadenosine (2CA), adenosine, 2‐phenylaminoadenosine (PAA), caused concentration‐dependent hyperpolarizations whilst N6‐(9‐fluorenylmethyl)adenosine (PD 117,413) was inactive at up to 100 μm.
The order of potency of adenosine analogues in depressing depolarization caused by a submaximal concentration of muscarine (100 nm) was: CPA > R‐PIA = 2C A > NEC A > S‐PIA > BZA > adenosine > PAA, where R‐ and S‐PIA = R(−)‐ and S(+)‐N6‐(2‐phenylisopropyl)adenosine, NECA = 5′N‐ethylcarboxamidoadenosine and BZA = N6‐benzyladenosine. PD 117,413 was inactive at concentrations up to 100 μm. The maximum inhibitions of the muscarine‐induced depolarization by CPA, 2CA, NECA and BZA were similar. R‐PIA, S‐PIA and PAA produced similar maximal inhibitions which were significantly smaller than those produced by CPA.
Hyperpolarizations caused by adenosine were antagonized by the P1‐purinoceptor selective antagonist 1,3‐dimethyl‐8‐phenylxanthine (8PT) and by the selective A1‐adenosine receptor antagonist, 1,3‐dipropyl‐8‐(4‐((2aminoethyl)amino)carbonylmethyloxyphenyl)xanthine (XAC). Hyperpolarizations caused by CPA, adenosine and PAA were antagonized by the A1‐selective antagonist, 8‐cyclopentyl‐1,3‐dipropylxanthine (DPCPX) but not by the A2‐selective antagonist, 3,7‐dimethyl‐1‐propargylxanthine (DMPX).
Inhibition of the muscarinic‐induced depolarization by CPA was antagonized by 8PT and DPCPX but not by DMPX.
It is concluded that the neurones of the rat SCG possess P1‐purinoceptors of the A1‐adenosine receptor subtype which mediate hyperpolarization and inhibition of depolarization caused by muscarine.
Serum corticosterone, interleukin‐1 and tumour necrosis factor in rat experimental endotoxaemia: comparison between Lewis and Wistar strains
Authors: Perretti M. , Duncan G.S. , Flower R.J. , Peers S.H. 
Published: July 2012

Circulating corticosterone, interleukin‐1 (IL‐1) and tumour necrosis factor‐α (TNFα) activities in serum of Lewis and Wistar rats were measured following injection of lipopolysaccharide (LPS). IL‐1 was measured as ‘lymphocyte activation factor’ (LAF) activity following precipitation of inhibitory activity with polyethylene glycol. TNFα activity was measured as cytotoxic activity.
Compared to the Wistar, the Lewis rat had higher circulating LAF and TNF activities following LPS, and release of both cytokines was prolonged in this strain.
Corticosterone increases in response to LPS were less in the Lewis than in the Wistar rat following the initial peak at 1 h; basal corticosterone was lower in the Lewis rat.
Adrenalectomized Lewis rats had even greater amounts of circulating LAF and TNF activities following LPS than did intact animals; the effect of adrenalectomy was not however mimicked by acute treatment with the steroid receptor antagonist, RU486, suggesting that endogenous corticosteroids did not acutely control cytokine release.
Although in vivo administration of anti‐murine IL‐1α antiserum significantly lowered LAF activity of serum, circulating corticosterone in response to LPS was not affected. Similarly, treatment with anti‐murine TNFα monoclonal antibody (mAb) abrogated TNF activity without affecting corticosterone, suggesting that other mediators may be responsible for corticosterone release following LPS.
This ‘overproduction’ of inflammatory cytokines together with lower circulating corticosterone may contribute to the susceptibility of the Lewis rat to diseases such as adjuvant arthritis or experimental allergic encephalomyelitis.
Characterization and pharmacological modulation of antigen‐induced peritonitis in actively sensitized mice
Authors: Zuany‐Amorim Cláudia , Leduc Dominique , Vargaftig B. Boris , Pretolani Marina 
Published: July 2012

The intraperitoneal (i.p.) injection of 1 or 10 μg ovalbumin to sensitized Balb/c mice led to an acute histamine release, firstly evidenced 1 min after the challenge and returning to basal levels 30 min thereafter. This phenomenon was unaccompanied by protein extravasation. A dose‐dependent increase in the amounts of immunoreactive leukotriene (LT) C4 and LTB4 was observed in the peritoneal washing from sensitized mice 6 h after 1 or 10 μg ovalbumin administration. In separate experiments, the i.p. administration of 1 mg activated zymosan to non‐immunized mice was followed by a marked protein extravasation, and by immunoreactive LTC4 and LTB4, but not histamine, release in mouse peritoneum 1 h after its injection.
Mediator release in the mice peritoneal cavity was concomitant with a transient neutrophil infiltration, which peaked at 6 h and returned to basal levels thereafter. An intense eosinophil accumulation starting at 24 h, peaking at 48 h and returning to basal values at 164 h, was also observed.
Ovalbumin (1 μg)‐induced eosinophilia, observed at 24 h, was reduced by the pretreatment of the animals with dexamethasone (1 mg kg−1, s.c.) or with the 5‐lipoxygenase inhibitor, BWA4C (20 mg kg−1, s.c.), whereas indomethacin (2 mg kg−1, s.c.) and the platelet‐activating factor (PAF)‐antagonist SR 27417 (10 mg kg−1, s.c.) were ineffective. These results indicate that metabolites of arachidonic acid of lipoxygenase pathway, but not cyclo‐oxygenase derivatives or PAF, mediate antigen‐induced eosinophil accumulation in the mouse peritoneum.
The histamine H1 receptor antagonist drug, cetirizine (15–30 mg kg−1, s.c.) markedly reduced ovalbumin‐induced eosinophil accumulation under conditions where terfenadine was ineffective, suggesting that the effect of cetirizine was not related to the inhibition of the H1 receptor effects of histamine.
The immunosuppressive agent, FK‐506 (1–2 mg kg−1, s.c.) and the protein synthesis inhibitor, cylcoheximide, when administered either in situ (0.06 ng/cavity) or systemically (5 mg kg−1, s.c.), prevented antigen‐induced eosinophil accumulation in the mouse peritoneum, contributing to the concept that substances (probably cytokines) originating from lymphocytes may be involved in the modulation of the eosinophilotactic response in this model.
The results of the present study indicate that the i.p. administration of ovalbumin to actively sensitized mice induced late eosinophil accumulation in the peritoneal cavity. This phenomenon, which may be in part mediated by the release of lipoxygenase metabolites and/or by newly generated factors, such as T‐lymphocytes‐derived eosinophilotactic cytokines, offers an interesting tool to investigate the mechanism of action of anti‐allergic and anti‐inflammatory drugs.
Characterization of EP‐receptor subtypes involved in allodynia and hyperalgesia induced by intrathecal administration of prostaglandin E2 to mice
Authors: Minami Toshiaki , Nishihara Isao , Uda Rumiko , Ito Seiji , Hyodo Masayoshi , Hayaishi Osamu 
Published: July 2012

Intrathecal (i.t.) administration of prostaglandin E2 (PGE2) to conscious mice induced allodynia, a state of discomfort and pain evoked by innocuous tactile stimuli, and hyperalgesia as assessed by the hot plate test. We characterized prostaglandin E receptor subtypes (EP1–3) involved in these sensory disorders by use of 7 synthetic prostanoid analogues.
Sulprostone (EP1 < EP3) induced allodynia over a wide range of dosages from 50 pg to 5 μg kg−1. The maximal allodynic effect was observed at 5 min after i.t. injection, and the response gradually decreased over the experimental period of 50 min. This sulprostone‐induced allodynia showed a time course similar to that induced by PGE2.
17‐Phenyl‐ω‐trinor PGE2 (EP1 > EP3) and 16,16‐dimethyl PGE2 (EP1 = EP2 = EP3) were as potent as PGE2 in inducing allodynia, and more potent than sulprostone. Butaprost (EP2), 11‐deoxy PGE1 (EP2 = EP3), MB 28767 (EP3), and cicaprost (prostaglandin I2 (IP‐) receptor) induced allodynia, but with much lower scores. 13,14‐Dihydro‐15‐keto PGE2, a metabolite of PGE2, did not induce allodynia.
16,16‐Dimethyl PGE2 as well as PGE2 induced hyperalgesia over a wide range of dosages (16,16‐dimethyl PGE2: 5 pg–0.5 μg kg−1 PGE2: 50 pg–0.5 μg kg−1) with two apparent peaks at 0.5 ng kg−1 and 0.5 μg kg−1. Sulprostone (EP1 < EP3) and 17‐phenyl‐ω‐trinor PGE2 (EP1 > EP3) showed a bell‐shaped hyperalgesia at lower doses of 5 pg–5 ng kg−1 and 50 pg–50 ng kg−1, respectively. MB 28767 (EP3) showed a monophasic hyperalgesic action over a wide range of dosages at 50 pg–5 μg kg−1. Butaprost (EP2) induced hyperalgesia at doses higher than 50 ng kg−1.
These results demonstrate that PGE2 may exert allodynia through the EP1‐receptor and hyperalgesia through EP2‐ and EP3‐receptors in the mouse spinal cord.
Characterization of the effects of 2‐methylthio‐ATP and 2‐chloro‐ATP on brain capillary endothelial cells: similarities to ADP and differences from ATP
Authors: Vigne Paul , Feolde Erick , Breittmayer Jean Philippe , Frelin Christian 
Published: July 2012

Brain capillary endothelial cells responded to 2‐methylthio‐ATP (2MeSATP) by large increases in [Ca2+]i (EC50 = 27 nm) that were partially dependent on the presence of extracellular Ca2+ and that were not associated with a measurable production of inositol phosphates.
2‐chloro‐ATP (2ClATP) raised [Ca2+]i in a biphasic manner. At low concentrations, intracellular Ca2+ mobilization was not associated with a measurable production of inositol phosphates. At concentrations >30 μm, 2ClATP activated phospholipase C.
The actions of 2ClATP, 2MeSATP and ADP on [Ca2+]i were additive to those of ATP and UTP. Non‐additive actions of 2MeSATP and of low concentrations of ADP or of 2ClATP were observed.
Cross desensitizations of the actions of ADP, 2MeSATP and 2ClATP were observed. None of them desensitized cells to the action of ATP.
It is concluded that 2MeSATP and low concentrations of 2ClATP and ADP induce intracellular Ca2+ mobilization by acting via an atypical P2y purinoceptor that is not coupled to phospholipase C. At high concentrations, 2C1ATP also activates phospholipase C and further increases [Ca2+]i probably by acting on P2u purinoceptors.