bluuebunny/crossref_metadata_2025_split huggingface dataset:
Contribution of intercellular adhesion molecule 1 (ICAM‐1) to the pathogenesis of splanchnic artery occlusion shock in the rat
Authors: Squadrito Francesco , Altavilla Domenica , Canale Patrizia , Ioculano MariaPatrizia , Campo Giuseppe M. , Ammendolia Letteria , Squadrito Giovanni , Saitta Antonino , Calapai Gioacchino , Caputi Achille P. 
Published: July 2012

It has been suggested that leukocytes play a key role in the pathogenesis of splanchnic artery occlusion shock. Intercellular adhesion molecule 1 (ICAM‐1) is an adhesion molecule of crucial importance in the phenomenon of leukocyte accumulation.
We investigated the involvement of ICAM‐1 in the pathogenesis of splanchnic artery occlusion shock. Splanchnic artery occlusion (SAO) shock was induced in anaesthetized rats by clamping splanchnic arteries for 45 min. Sham‐operated animals were used as controls. Survival time, serum tumour necrosis factor‐α (TNF‐α), white blood cell (WBC) count, mean arterial blood pressure, myeloperoxidase activity (MPO; studied as a quantitative means to assess leukocyte accumulation) and the responsiveness to acetylcholine of aortic rings were investigated. SAO shocked rats had a decreased survival time (90 ± 9.5 min, while sham‐shocked rats survived more than 4 h), reduced mean arterial blood pressure, increased serum levels of TNF‐α (201 ± 10 u ml−1) and MPO activity in the ileum (0.15 ± 0.03 u × 10−3 per g tissue) and in the lung (1.9 ± 0.8 u × 10−3 per g tissue), leukopenia and reduced responsiveness to acetylcholine (ACh, 10nM‐10 μm) of aortic rings.
Administration of monoclonal antibody raised against rat ICAM‐1 significantly increased survival time (225 ± 9 min), reduced leukopenia and MPO activity both in the ileum (0.031 ± 0.003 u × 10−3 per g tissue) and in the lung 0.23 ± 0.03 u × 10−3 per g tissue), improved the cardiovascular changes and restored the responsiveness to ACh of aortic rings.
Our findings are consistent with an involvement of adhesion mechanisms in vivo in the pathogenesis of SAO shock and suggest that specific adhesion mechanisms, which support leukocyte accumulation, may represent potentially important therapeutic targets in circulatory shock.
Blockade by dendrotoxin homologues of voltage‐dependent K+ currents in cultured sensory neurones from neonatal rats
Authors: Hall Adam , Stow John , Sorensen Roger , Dolly J. Oliver , Owen David 
Published: July 2012

Homologues of dendrotoxin (Dtx) were isolated from the crude venom of Green and Black Mamba snakes and examined for K+ channel blocking activity in neonatal rat dorsal root ganglion cells (DRGs) by whole‐cell patch clamp recording.
Outward potassium current activated by depolarization was composed of two major components: a slowly inactivating current (SIC, τdecay ≅ 50ms, 200 ms and 2 s), and a non‐inactivating current (NIC, τdecay > 2 min). Tail current analysis revealed two time constants of deactivation of total outward current, 3–12 ms and 50–150 ms (at −80 mV) which corresponded to SIC and NIC, respectively.
All the homologues (α‐, β‐, γ‐ and γ‐Dtx and toxins I and K) blocked outward current activated by depolarization in a dose‐dependent manner. The most potent in blocking total outward current was γ‐Dtx (EC50 of 0.5 ± 0.2 nm), although there were no statistically significant differences in potency between any of the homologues.
Qualitative differences in the nature of the block were noted between homologues. In particular, the block by γ‐Dtx was time‐dependent, whereas that by γ‐Dtx was not.
α‐Dtx was a much better blocker of SIC (EC50 = 1.0 ± 0.4 nm) than was γ‐Dtx (EC50 = 17.6 ± 5.8 nm). Furthermore, γ‐Dtx was selective for NIC (EC50 ± 0.24 ± 0.03 nm) over SIC and reduced the slow component of tail currents (NIC), preferentially. On the other hand, α‐Dtx did not significantly distinguish between SIC and NIC although tail current analysis showed that α‐Dtx preferentially reduced the fast component of tail currents (SIC).
The results confirm, using direct electrophysiological methods, that homologues of dendrotoxins from Mamba snake venom block K+ channels in rat sensory neurones. Furthermore, α‐Dtx and γ‐Dtx distinguish between sub‐types of K+ channels in these cells and may thus be useful pharmacological tools in other neuronal K+ channel studies.
Role of bradykinin in the hyperaemia following acid challenge of the rat gastric mucosa
Authors: Pethö Gábor , Jocič Milana , Holzer Peter 
Published: July 2012

This study examined whether the hyperaemia following acid challenge of the rat gastric mucosa involves bradykinin, a peptide formed in response to tissue injury.
Gastric mucosal blood flow in urethane‐anaesthetized rats was assessed by the hydrogen gas clearance method. Infusion of a bradykinin solution (10 μm) into the gastric wall augmented gastric mucosal blood flow by a factor of 2.3, an effect that was prevented by the bradykinin B2 antagonist Hoe‐140 (icatibant; 100 μmol kg−1, i.v.).
I.v. injection of bradykinin (20–60 nmol kg−1) caused a 2.3‐3.5 fold increase in blood flow through the left gastric artery as measured by the ultrasonic transit time shift technique. The hyperaemic effect of bradykinin in this gastric artery was also prevented by Hoe‐140 (100 μ mol kg−1, i.v.).
Gastric acid backdiffusion was evoked by perfusing the stomach with 15% ethanol, to break the gastric mucosal barrier, in the presence of luminal acid. Depending on the concentration of acid (0.05 and 0.15 M HC1), this procedure increased gastric mucosal blood flow by a factor of 1.6‐2.8 and caused formation of gross damage in 1.5‐3% of the glandular mucosa. Hoe‐140 (100 μmol kg−1, i.v.) failed to alter the moderate vasodilatation seen in the presence of 0.05 M HC1 but significantly (P < 0.05) attenuated the marked hyperaemia and enhanced the gross mucosal damage observed in the presence of 0.15 M HC1.
These data show that bradykinin is able to enhance gastric mucosal blood flow via activation of B2 receptors. It appears as if this kinin is formed during severe acid challenge of the rat gastric mucosa and participates in the hyperaemic reaction to gastric acid backdiffusion.
Substrate specificity of the di/tripeptide transporter in human intestinal epithelia (Caco‐2): identification of substrates that undergo H+‐coupled absorption
Authors: Thwaites David T. , Hirst Barry H. , Simmons Nicholas L. 
Published: July 2012

pH‐dependent transepithelial transport and intracellular accumulation of the hydrolysis‐resistant dipeptide glycylsarcosine (Gly‐Sar) have been demonstrated in the model human intestinal epithelial cell line, Caco‐2.
Experiments with BCECF (2′,7′‐bis(2‐carboxyethyl)‐5(6)‐carboxyfluorescein)‐loaded Caco‐2 cells demonstrated that dipeptide (Gly‐Sar) transport across the apical membrane is coupled to proton flow into the cell.
A range of postulated substrates for the intestinal di/tripeptide carrier were tested for their abilities to: (a) inhibit pH‐dependent [14C]Gly‐Sar apical‐to‐basal transport and intracellular accumulation and (b) stimulate H+ flow across the apical surface of BCECF‐loaded Caco‐2 cell monolayers.
A range of compounds (including Gly‐Gly, Leu‐Leu, Gly‐Gly‐Gly, cefadroxil and cephalexin) caused marked acidification of intracellular pH when perfused at the apical surface of Caco‐2 cell monolayers. In contrast leucine and D‐Leu‐D‐Leu failed to induce proton flow. The ability to induce proton‐flow across the apical surface by these compounds, in this intestinal epithelium, was directly correlated to the relative inhibitory effects on [14C]‐Gly‐Sar transport and accumulation.
The determination of substrate‐induced intracellular pH change in the Caco‐2 cell system may provide a useful rapid screen for candidate substrates for absorption via H+‐coupled transport mechanisms such as the intestinal di/tripeptide carrier in an appropriate physiological context.
Smooth muscle relaxing effects of NO, nitrosothiols and a nerve‐induced relaxing factor released in guinea‐pig colon
Authors: Iversen H.H. , Gustafsson L.E. , Leone A.M. , Wiklund N.P. 
Published: July 2012

The aim of the present study was to compare the biological activity of S‐nitroso‐L‐cysteine (CYSNO), S‐nitrosoglutathione (GSNO), S‐nitroso‐N‐acetyl‐D, L‐penicillamine (SNAP) and hydrox‐ylamine to that of nitric oxide (NO) and a vascular relaxing factor released by nerve stimulation in the guinea‐pig intestine. The biological activity was examined in a bioassay system with guinea‐pig colon as donor tissue and a series of spiral strips of rabbit aorta without endothelium as detector tissues.
Electrical stimulation of the guinea‐pig colon released a vascular relaxing factor. The half‐life of the relaxing factor down the bioassay cascade was the same as exogenously applied NO. Nω‐nitro‐L‐arginine (L‐NOARG) inhibited the release of bioactivity.
The relaxations of the assay tissues caused by exogenous CYSNO also declined during the passage down the cascade. However, in the presence of L‐cysteine (10−5 m) the half‐life of CYSNO increased and there was no significant breakdown through the cascade. In contrast, the half‐life of applied NO and the vascular relaxing factor released by nerve stimulation was unaffected by the presence of L‐cysteine.
Exogenously applied GSNO (20–50 nm), SNAP (2–4 nm) and hydroxylamine (300–600 nm) caused relaxations that did not decline during the passage down the cascade.
In summary, the relaxation of the bioassay tissues during nerve stimulation was indistinguishable from the relaxation induced by NO, whereas relaxations induced by CYSNO, GSNO, SNAP and hydroxylamine showed different pharmacological profiles. The released bioactivity is thus likely to be NO itself.
Neutral endopeptidase (NEP) inhibition in rats with established pulmonary hypertension secondary to chronic hypoxia
Authors: Thompson J.S. , Sheedy W. , Morice A.H. 
Published: July 2012

Atrial natriuretic peptide (ANP) causes vasorelaxation in the pulmonary vasculature. ANP levels are elevated in conditions characterized by pulmonary hypertension and it has been hypothesized that ANP may be autoregulatory in the pulmonary circulation.
One route of ANP metabolism in vivo is by the action of the enzyme neutral endopeptidase (NEP). We have studied the effects of the NEP inhibitor, SCH 42495, in rats with established pulmonary hypertension secondary to chronic hypoxia.
Rats (n = 32) were divided into 4 groups. Normoxic controls were kept in air for 10 days (NC10) and all other animals were placed in a normobaric hypoxic chamber (Fi 02 10%). Chronic hypoxic controls were studied at 10 days (CHC10). After 10 days hypoxia the two remaining groups received oral treatment for a further 10 days, consisting of either SCH 42495 (30 mg kg−1, twice daily CHT20) or methyl cellulose vehicle (0.4%, twice daily, CHV20).
Animals were anaesthetized and blood collected for measurement of plasma ANP. Hearts were dissected and ventricles weighed and the histology of the pulmonary vasculature examined.
CHC10 rats had significant right ventricular hypertrophy (0.53 ± 0.08) and pulmonary vascular remodelling (29.0 ± 0.01%) and had gained significantly less body weight (33.2 ± 5.5 g) than NC10 rats (0.31 ± 0.04, 10.9 ± 0.01%, and 59.2 ± 11.9 g respectively). CHC10 rats had significantly elevated plasma ANP levels (58.4 ± 9.9 pM) compared with NC10 rats (23.9 ± 32pM). Treatment with SCH 42495 caused a significant reduction in pulmonary vascular remodelling (25.0 ± 0.01%) and right ventricular hypertrophy (0.52 ± 0.09) in CHT20 rats compared with CHV20 controls (33.0 ± 0.02% and 0.61 ± 0.09 respectively). Pulmonary vascular remodelling was also significantly lower in CHT20 rats than CHC10 animals.
Thus, short term inhibition of NEP causes regression of established pulmonary vascular remodelling and may be a useful therapeutic strategy in pulmonary hypertension.
Interactions of constitutive nitric oxide with PAF and thromboxane on rat intestinal vascular integrity in acute endotoxaemia
Authors: László F. , Whittle B.J.R , Moncada S. 
Published: July 2012

The involvement of endogenous platelet activating factor (PAF) and thromboxane A2 in the acute microvascular damage in the ileum and colon induced by the nitric oxide (NO) synthase inhibitor, NG‐nitro‐L‐arginine methyl ester (1‐NAME) following endotoxin administration was investigated in the rat over a 1 h period.
Administration of 1‐NAME (1–10 mg kg−1, s.c.) concurrently with E. coli lipopolysaccharide (LPS;
mg kg1, i.v.) dose‐dependently increased vascular permeability in the ileum and colon, as determined by the leakage of radiolabeled albumin, and caused macroscopic mucosal damage in the ileum determined 1 h later. Neither LPS administration nor 1‐NAME (5 mg kg1) alone affected resting vascular permeability.
Infusion of phenylephrine (lOμg kg−1 min−1, i.v. for 1 h) caused an elevation in blood pressure similar to that found following 1‐NAME administration (5 mg kg−1, i.v. or s.c), but did not increase intestinal vascular permeability, when administered with LPS (3 mg kg−1, i.v.).
The increased vascular permeability in the ileum and colon and macroscopic damage in the ileum, induced by 1‐NAME (5 mg kg−1, s.c.) and LPS (3 mg kg−1, i.v.) was dose‐dependently inhibited following s.c. pretreatment (15min before challenge) with the thromboxane synthase inhibitors, OKY 1581 (5–25 mg kg−1) or 1‐benzyl‐imidazole (1–50 mg kg−1), or with the thromboxane receptor antagonist, BM 13177 (0.2‐2 mg kg−1).
Pretreatment with the cyclo‐oxygenase inhibitor, indomethacin (2‐5mg kg−1, s.c, 15min before challenge) reduced the microvascular injury in the ileum and colon and macroscopic lesions in the ileum, observed after the concurrent administration of 1‐NAME and LPS.
Pretreatment (15min) with the PAF‐receptor antagonists, WEB 2086 (0.5‐1 mg kg−1, s.c) or BN 52021 (2.5–10 mg kg−1, s.c.) likewise attenuated this intestinal vascular injury.
Combined administration of low doses of 1‐benzyl‐imidazole (1 mg kg−1) with WEB 2086 (0.5 mg kg−1) 15min before 1‐NAME and LPS challenge, abolished this vascular damage and macroscopic injury.
These results suggest that PAF and thromboxane A2 are released acutely following challenge with a low dose of endotoxin. However, these mediators do not appear to injure the intestinal microvascular bed unless NO synthase is concurrently inhibited. Such findings support the protective role of constitutively‐formed NO, counteracting the injurious vascular actions of cytotoxic mediators released under pathological conditions.
Participation of tumour necrosis factor and nitric oxide in the mediation of vascular dysfunction in splanchnic artery occlusion shock
Authors: Squadrito Francesco , Altavilla Domenica , Canale Patrizia , Ioculano Mariapatrizia , Campo Giuseppe M. , Ammendolia Letteria , Ferlito Marcella , Zingarelli Basilia , Squadrito Giovanni , Saitta Antonino , Caputi Achille P. 
Published: July 2012

Splanchnic artery occlusion (SAO) shock is characterized by irreversible circulatory failure. Tumour necrosis factor (TNF‐α) may affect the 1‐arginine/nitric oxide (NO) pathway, thus contributing to the cardiovascular derangements of circulatory shock.
We investigated the contribution of both TNF‐α and the 1‐arginine/nitric oxide pathway to the vascular dysfunction of SAO shock. Anaesthetized rats, subjected to total occlusion of the superior mesenteric artery and the coeliac trunk for 45 min developed a severe shock state (SAO shock) resulting in a fatal outcome within 75–90 min after the release of occlusion. Sham operated animals were used as controls. SAO shocked rats had also a marked hypotension and enhanced macrophage and serum levels of TNF‐α. Furthermore, aortic rings from shocked rats showed a marked hyporeactivity to phenylephrine (PE 1 nm‐10 μm) and reduced responsiveness to acetylcholine (ACh lOnM‐lOμm). Endothelium‐denuded aortic rings had also a marked hyporeactivity to phenylephrine, which was restored to control values by in vitro administration of N° nitro‐1‐arginine‐methyl ester (1‐NAME 10 μm).
In vivo administration of cloricromene (2 mg kg−1, i.v.), an inhibitor of TNF‐α biosynthesis, increased survival, enhanced mean arterial blood pressure and reduced macrophage and serum levels of TNF‐α. Furthermore, aortic rings from shocked rats treated with cloricromene exhibited a greater contractile response to phenylephrine and improved responsiveness to ACh when compared to aortic rings from vehicle‐treated SAO shocked rats.
Our results suggest that TNF‐α alters both endothelial and muscular L‐arginine/nitric oxide pathways which in turn produce vascular dysfunction in SAO shock.
‘Sensory‐efferent’ neural control of mucus secretion: characterization using tachykinin receptor antagonists in ferret trachea in vitro
Authors: Ramnarine Sean I. , Hirayama Yoshitaka , Barnes Peter J. , Rogers Duncan F. 
Published: July 2012

We characterized the tachykinin receptor(s) mediating ‘sensory‐efferent’ neural control of release of 35S04‐labelled macromolecules (mucus) from ferret trachea in vitro in Ussing chambers using selective tachykinin antagonists. Secretion was induced by substance P (SP), neurokinin A (NKA), capsaicin, the NK1 tachykinin receptor agonist [Sar9, Met(O2))11] substance P ([Sar9SP), or acetylcholine (ACh), or by electrical stimulation of nerves. Antagonists used were FK888 and L‐668,169, selective for the NK, receptor, SR 48968, selective for the NK2 receptor, and FK224, a dual antagonist at NK1 and NK2 receptors. The selectivity of FK888 and SR 48968 was examined on NKA‐induced contraction of ferret tracheal smooth muscle in vitro.
SP (1 μm) increased mucus secretion by 695% above vehicle controls. FK888 (0.1 μm‐30μm) inhibited SP‐induced secretion in a dose‐dependent manner, with complete inhibition at IOJXM and an IC50 of 1 μm. L‐668,169 (1 μm) also completely inhibited SP‐induced secretion.
NKA (1 μm) significantly increased mucus secretion by 271% above baseline, a response which was completely inhibited by FK888 (10 μm) or L‐668,169 (μm). Secretion induced by ACh (10 μm: 317% above baseline) was not inhibited by FK888 but was inhibited by atropine. Capsaicin (10μm)‐induced secretion (456% above vehicle controls) was significantly inhibited by FK888 and by L‐668,169 (111% and 103% inhibition respectively).
Electrical stimulation (50 V, 10 Hz, 0.5 ms, 5 min) increased mucus output above baseline (increased by 12 to 26 fold), a response blocked by tetrodotoxin (0.1 μm). FK888 (10μm) inhibited the increase in secretion due to electrical stimulation by 47%. Atropine, propranolol and phentolamine in combination (APP) inhibited the response to electrical stimulation by 48%. The remaining NANC response, i.e. in the presence of APP, was further reduced by 66% with FK888. FK224 (10μm) inhibited neurally‐evoked secretion by 73%. SR 48968 (0.1 μm) had no effect on electrically‐stimulated or [Sar9]SP‐induced secretion.
NKA (10μm‐10μm: in the presence of DMSO control vehicle) induced tracheal smooth muscle contraction in a concentration‐dependent manner with a maximal contraction of 30% of the maximal response to ACh (10 μm) and an EC50 of 0.3 JIM. SR 48968 (0.1 μ in DMSO) inhibited the NKA‐induced contraction whereas FK888 did not. Neither antagonist had any inhibitory effect on ACh‐induced contraction.
We conclude that ‘sensory‐efferent’ neurogenic mucus secretion in ferret trachea in vitro is mediated via tachykinin NK1 receptors with no involvement of NK2 receptors. Potent and selective tachykinin antagonists may have therapeutic potential in bronchial diseases such as asthma and chronic bronchitis in which neurogenic mucus hypersecretion may be aetiologically important.
Nitric oxide, and not vasoactive intestinal peptide, as the main neurotransmitter of vagally induced relaxation of the guinea pig stomach
Authors: Desai K.M. , Warner T.D. , Bishop A.E. , Polak J.M. , Vane J.R. 
Published: July 2012

Nitric oxide synthase (NOS) was localized in the guinea pig stomach by immunocytochemistry. In vitro experiments were carried out on the isolated stomach of the guinea pig to study any possible links between nitric oxide (NO) and vasoactive intestinal peptide (VIP) in mediating relaxations induced by vagal stimulation.
NOS was localized to nerve cell bodies and nerve fibre varicosities of the myenteric plexus in wholemounts of the longitudinal muscle‐myenteric plexus of the stomach fundus. The NOS‐positive cells had a Dogiel type I morphology characteristic of motor neurones.
The cross‐sections of the stomach wall showed NOS‐positive neurones mainly in the myenteric plexus ganglia and NOS‐positive nerve fibre varicosities in the circular muscle layer.
Relaxations induced by vagal stimulation were almost completely prevented by 1‐NAME with an IC50 value of 5.5 × 10−6m. This inhibition was reversed by L‐arginine (2 μm).
VIP (100 nm) induced reproducible relaxations of the stomach. These were unaffected by tet‐rodotoxin (2μm) or NW‐nitro‐L‐arginine methyl ester (1‐NAME, 100 μm).
Desensitization to the relaxant effect of VIP partially reduced relaxations induced by vagal stimulation, glyceryl trinitrate or sodium nitroprusside but not noradrenaline.
These results show that NO has a neuronal origin in the guinea pig stomach, and support NO, and not VIP, as the major neurotranmitter of vagally induced gastric relaxation in the guinea pig.
β‐Adrenoceptors mediate inhibition of [3H]‐acetylcholine release from the isolated rat and guinea‐pig trachea: role of the airway mucosa and prostaglandins
Authors: Wessler Ignaz , Reinheimer Torsten , Brunn Gernot , Anderson Gary P. , Maclagan Jennifer , Racké Kurt 
Published: July 2012

Rat or guinea pig isolated tracheae were labelled with [3H]‐choline to measure evoked tritium outflow, which reflects neuronal release of [3H]‐acetylcholine. Tritium outflow was evoked either by electrical stimulation of the extrinsic vagal nerve (rat tracheae) or by 27 mm potassium (guinea pig tracheae).
In rat tracheae isoprenaline (0.01, 0.1 μm) inhibited evoked [3H]‐acetylcholine release, whereas β‐adrenoceptor‐selective agonists (fenoterol, formoterol, salbutamol) were ineffective.
The inhibitory effect of isoprenaline was abolished under the following conditions: (i) presence of propranolol (1 μm) or of the β‐selective antagonist CGP 20712 A (0.1 μm); (ii) removal of the mucosa at the start of the experiments; (iii) blockade of cyclooxygenase activity by 3 μm indomethacin.
In rat isolated tracheae prelabelled with [3H]‐arachidonic acid, isoprenaline (0.1 μm) but not formoterol (0.01 μm) enhanced the outflow of [3H]‐prostaglandins (PGD2, PGE2). This effect was blocked by 0.1 μm CGP 20712 A.
In guinea pig tracheae electrical stimulation of the extrinsic vagal nerve did not cause a constant release of [3H]‐acetylcholine, but 27 mm potassium elicited a reproducible release of [3H]‐acetylcholine. In this species both isoprenaline (0.1 μm) and formoterol (0.01 μm) inhibited evoked [3H]‐acetylcholine release. Inhibition was abolished under the following conditions: (i) presence of propranolol (1 μm) or of the β2‐selective antagonist ICI 118551 (0.3 μm); (ii) removal of the mucosa at the start of the experiments; (iii) blockade of cyclooxygenase activity by 3 μm indomethacin.
In conclusion, the present experiments have demonstrated that activation of β‐adrenoceptors localized in the mucosa mediates inhibition of [3H]‐acetylcholine release from the neuroeffector junctions of the pulmonary, parasympathetic nerves most probably by the liberation of inhibitory prostaglandins from the airway mucosa. The adrenoceptor subtype involved differs in rat (β1 subtype) and guinea pig (β 2subtype) airways.