bluuebunny/crossref_metadata_2025_split huggingface dataset:
Roles of prostacyclin, EDRF and active oxygens in leukocyte‐dependent platelet adhesion to endothelial cells induced by platelet‐activating factor in vitro
Authors: Hirafuji Masahiko , Shinoda Hisashi 
Published: July 2012

The mechanism of polymorphonuclear leukocyte (PMN)‐dependent platelet adhesion to cultured endothelial cells induced by platelet‐activating factor (PAF) was investigated to determine whether PMNs release or generate any factor(s) capable of inducing platelet adhesion, and the roles of prostacyclin and endothelium‐derived relaxing factor (EDRF).
Cell‐free supernatants, sonicates or rapid filtrates of PAF‐stimulated PMN suspensions did not induce platelet adhesion to endothelial cells, but the PMN sonicates induced platelet adhesion when endothelial cells were pretreated with both aspirin and NG‐nitro‐lm‐arginine (l‐NOARG). Its microphotograph showed that mainly platelet aggregates adhered to the endothelial cell surface.
Platelet adhesion induced by the PMN sonicates to aspirin‐ and l‐NOARG‐pretreated endothelial cells was dose‐dependently prevented by OP‐41483 (1–100 nm), and slightly by l‐arginine (1 mm). The inhibition of platelet adhesion by OP‐41483 and l‐arginine was potentiated by their combination.
WEB 2170 (3 μm), a PAF antagonist, inhibited platelet adhesion induced by the PMN sonicates. However, PAF alone did not induce significant platelet adhesion to aspirin‐ and l‐NOARG‐treated endothelial cells.
Platelet adhesion induced by the PMN sonicates was not suppressed by AA‐861 and indomethacin. However, both superoxide dismutase and catalase significantly inhibited platelet adhesion, and, in combination, their inhibitory effect was synergistically potentiated. Mannitol had no effect. It was also significantly inhibited by α1‐antitrypsin, whereas chymostatin and elastatinal had no effect.
PAF‐induced platelet adhesion to endothelial cells in the presence of intact PMNs was not suppressed by indomethacin and AA‐861, or by protease inhibitors. SOD alone, and in combination with catalase, caused a slight but significant inhibition, while catalase and mannitol by themselves had no effect.
PMN‐induced platelet adhesion was slightly inhibited by OP‐41483 (100 nm). l‐Arginine (1 mm) alone had no effect, but slightly potentiated the effect of OP‐41483. This platelet adhesion was not accompanied by suppression of prostacyclin synthesis.
The results with the PMN sonicates show that prostacyclin, EDRF and active oxygens are important modulators of intercellular interactions between platelets and endothelial cells. These results further suggest that the mechanism of intact PMN‐dependent platelet adhesion is primarily through platelet‐endothelial cell interactions in which leukocyte‐derived active oxygens play a role, but does not involve platelet‐platelet interactions inhibitable by prostacyclin.
Hoe 694, a new Na+/H+ exchange inhibitor and its effects in cardiac ischaemia
Authors: Scholz W. , Albus U. , Lang H.J. , Linz W. , Martorana P.A. , Englert H.C. , Schölkens B.A. 
Published: July 2012

The benzoylguanidine derivative Hoe 694 ((3‐methylsulphonyl‐4‐piperidino‐benzoyl) guanidine methanesulphonate) was characterized as an inhibitor of Na+/H+ exchange in rabbit erythrocytes, rat platelets and bovine endothelial cells. The potency of the compound was slightly lower or comparable to ethylisopropyl amiloride (EIPA).
To investigate a possible cardioprotective role of the Na+/H+ exchange inhibitor Hoe 694, rat isolated working hearts were subjected to ischaemia and reperfusion. In these experiments all untreated hearts suffered ventricular fibrillation on reperfusion. Addition of 10−7 m Hoe 694 to the perfusate almost abolished reperfusion arrhythmias in the rat isolated working hearts.
Hoe 694 reduced the release of lactate dehydrogenase (LDH) and creatine kinase (CK), which are indicators of cellular damage during ischaemia, into the venous effluent of the hearts by 60% and 54%, respectively.
The tissue content of glycogen at the end of the experiments was increased by 60% and the high energy phosphates ATP and creatine phosphate were increased by 240% and 270% respectively in the treated hearts as compared to control hearts.
Antiischaemic effects of the Na+/H+ exchange inhibitor, Hoe 694, were investigated in a second experiment in anaesthetized rats undergoing coronary artery ligation. In these animals, pretreatment with Hoe 694 caused a dose‐dependent reduction of ventricular premature beats and ventricular tachycardia as well as a complete suppression of ventricular fibrillation down to doses of 0.1 mg kg−1, i.v. Blood pressure and heart rate remained unchanged.
We conclude that the new Na+/H+ exchange inhibitor, Hoe 694, shows cardioprotective and antiarrhythmic effects in ischaemia and reperfusion in rat isolated hearts and in anaesthetized rats. In view of the role which Na+/H+ exchange seems to play in the pathophysiology of cardiac ischaemia these effects could probably be attributed to Na+/H+ exchange inhibition.
Functional characterization of three adenosine receptor types
Authors: Gurden M.F. , Coates J. , Ellis F. , Evans B. , Foster M. , Hornby E. , Kennedy I. , Martin D.P. , Strong P. , Vardey C.J. , Wheeldon A. 
Published: July 2012

The purpose of the present study was to classify adenosine receptors into A1 and A2 subtypes in a wide range of isolated tissues and cell types (rat adipocytes and atria, guinea‐pig ileum and atria (A1); guinea‐pig aorta, dog coronary artery and human platelets and neutrophils (A2)) using the R‐ and S‐diastereoisomers of N‐phenylisopropyladenosine (PIA), N‐cyclopentyladenosine (CPA), the novel compound, N‐[(1S,trans)‐2‐hydroxycyclopentyl]adenosine (GR79236), N‐[(2‐methylphenyl)methyl]adenosine (metrifudil), 2‐(phenylamino)adenosine (CV1808), and 2‐[[2‐[4‐(2‐carboxyethyl)phenyl]ethyl]amino]‐N‐ethylcarboxamidoadenosine (CGS21680); N‐ethylcarboxamidoadenosine (NECA) was used as a standard.
Results obtained in all tissue preparations previously reported to contain A1‐receptors could be described by a single rank order of agonist potency: CPA ≥ GR79236, R‐PIA ≥ NEC A > > S‐PIA ≥ metrifudil ≥ CV1808, CGS21680.
In contrast, two distinct rank orders of agonist potency were observed in preparations previously reported to contain A2‐receptors. In dog coronary artery, human neutrophils and platelets the rank order of potency was: CV1808, CGS21680 ≥ NECA > R‐PIA ≥ metrifudil ≥ CPA > GR79236, S‐PIA. However, in guinea‐pig aorta the rank order was: NECA > metrifudil > R‐PIA, CPA > CV1808, GR79236 ≥ S‐PIA, CGS21680.
The results of this study are consistent with the existence of three types of adenosine receptor: A1‐and two subtypes of A2‐receptor. The receptor present in dog coronary artery, human platelets and neutrophils, probably corresponds to the A2a subtype, whilst that present in the guinea‐pig aorta may be of the A2b subtype.
Effect of RP 67580, a non‐peptide neurokinin1 receptor antagonist, on facilitation of a nociceptive spinal flexion reflex in the rat
Authors: Laird J.M.A. , Hargreaves R.J. , Hill R.G. 
Published: July 2012

In order to examine the contribution of neurokinin1 (NK1) receptors to facilitation of a spinal nociceptive reflex in the rat, we have investigated the effects of RP 67580 ((3aR,7aR)‐7,7‐diphenyl‐2(1‐imino‐2‐(2‐methoxyphenyl/ethyl)perhydroisoindole)), a non‐peptide neurokinin1 (NK1) receptor antagonist, selective for the rodent receptor sub‐type, on the activity of individual motorunits. These results were compared with the effects of RP 68651, the inactive 3aS, 7aS enantiomer of RP 67580, as a control for non‐specific activity.
Experiments were performed on 15 rats anaesthetized with a continuous i.v. infusion of alphaxalone/alphadalone and spinalized at T9–10. Single unit recordings of motorunit activity from biceps femoris/semitendinosus were made with a concentric needle electrode. In each experiment, a vehicle dose followed by 4 sequential rising doses of either RP 67580 or RP 68651 were given at 15 min intervals. High intensity electrical stimuli were applied to the hindlimb receptive field of the motorunit at a rate of 1 per 60 s throughout the experiment to establish a baseline. A conditioning stimulus (20 of these stimuli at 1 Hz) was delivered 5 min after each dose and the effect of the size of the baseline response examined.
The conditioning stimulus evoked a facilitation of the baseline at the start of all experiments (mean increase ± s.e.mean = 151 ± 20%). RP 67580 attenuated this facilitation, with an ID50 (± s.e.mean) of 2.5 ± 4.2 μg kg−1, i.v., whereas RP 68651 at doses of up to 3 mg kg−1, i.v. did not. There was no statistically significant effect of drug on the baseline reflex, nor on the response to the conditioning stimulus. Doses of 300 and 3000 μg kg−1 of both RP 67580 and RP 68651 evoked small depressor effects on systemic arterial blood pressure.
We conclude that the facilitation of a spinal flexor reflex by noxious conditioning stimuli in the rat is mediated by NK1 receptors whereas the baseline reflex is not. The results suggest that brain penetrant NK1 receptor antagonists may have central anti‐nociceptive effects.
Pharmacology of a cloned potassium channel from mouse brain (MK‐1) expressed in CHO cells: effects of blockers and an ‘nactivation peptide’
Authors: Robertson Brian , Owen David G. 
Published: July 2012

Chinese hamster ovary cells (CHO), maintained in cell culture, were stably transfected with DNA for the MK‐1 voltage‐activated potassium channel, previously cloned from a mouse brain library.
Voltage‐activated currents were recorded by the whole‐cell patch clamp method. In CHO cells transfected with the vector only, there were no significant outward voltage activated currents. However, large outward voltage‐activated potassium currents were always observed in those cells which had been transfected with the vector containing the DNA encoding for MK‐1.
These potassium currents activated from −40 mV, and reversed at the potassium equilibrium potential. The half‐maximal conductance of MK‐1 was at −10 mV and had a slope factor of 11 mV when fitted with a Boltzmann function. There was only very slight (< 10%) inactivation of MK‐1 even at very large positive voltages.
MK‐1 was reversibly blocked by: 4‐aminopyridine (4‐AP, 0.1–4 mm), Toxin I (10–100 nm), mast cell degranulating peptide (1 μm), tetraethylammonium (TEA, 4–10mm), tedisamil (100 μm), quinine (100 μm) and ciclazindol (100 μm); all applied to the outside of the cell from a ‘U tube’ rapid perfusion system. 4‐AP may block closed as well as open MK‐1 potassium channels.
A synthetic 20 amino acid peptide derived from the N‐terminus sequence of the Shaker B potassium channel (the ‘inactivation peptide’) produced dramatic inactivation of MK‐1 when applied to the inside, but not the outside of the cell. Reducing peptide concentration or ‘degrading’ the peptide produced less inactivation.
The block of MK‐1 by the synthetic inactivation peptide was quite different in time dependence from block by internal TEA (0.4–4 mm), which probably blocks much more quickly but less potently than the peptide.
Differential effects of BQ‐123 against endothelin‐1 and endothelin‐3 on the rat vas deferens: evidence for an atypical endothelin receptor
Authors: Eglezos Anthony , Cucchi Paola , Patacchini Riccardo , Quartara Laura , Maggi Carlo Alberto , Mizrahi Jacques 
Published: July 2012

Endothelin‐1 and endothelin‐3 enhanced concentration‐dependently the rat vas deferens twitch response to electrical stimulation, endothelin‐1 being three times more potent. Sarafotoxin S6c was at least 200 times less active than endothelin‐1.
The response to endothelin was antagonized in a competitive manner by the supposedly selective ETA receptor antagonist, BQ‐123 (pA2:7.0 ± 0.1). In contrast, the endothelin‐1 concentration‐response curve was only shifted two fold in the presence of 10 μm BQ‐123, while no effect was observed at 1 μm.
This evidence suggests the rat vas deferens contains an endothelin receptor not conforming to the ETA/ETB receptor subtype classification so far proposed.
Effects of rolipram and siguazodan on the human isolated bronchus and their interaction with isoprenaline and sodium nitroprusside
Authors: Qian Y. , Naline E. , Karlsson J.‐A. , Raeburn D. , Advenier C. 
Published: July 2012

The effects of the selective inhibitors of cyclic AMP phosphodiesterase type IV (rolipram) and type III (siguazodan) and their interactions with isoprenaline and sodium nitroprusside have been studied in the human isolated bronchus.
On bronchi under resting tone rolipram was, in terms of potency (pD2 = 7.77 ± 0.14, n = 8), very similar to isoprenaline (pD2 = 7.31 ± 0.12, n = 12) and salbutamol (pD2 = 7.12 ± 0.17, n = 10) and approximately 10 fold more potent than siguazodan (pD2 = 6.80 ± 0.12, n = 6). In terms of efficacy (Emax, expressed as percentage of maximal effect induced by theophylline 3 mm), both rolipram and siguazodan were less efficient (Emax = 74 ± 6.7%, n = 8 and 66 ± 7.5%, n = 6, respectively) than isoprenaline (Emax = 98 ± 0.4%, n = 12) and salbutamol (Emax = 83 ± 2.4%, n = 10).
During precontraction induced by methacholine (3 × 10−7 m) or acetylcholine (10−3 m), concentration‐response curves to rolipram and siguazodan were shifted to the right and maximal effects reduced. Rolipram was more potent than siguazodan and, in terms of efficacy, it was less active.
Rolipram 10−8 and 10−7 m but not siguazodan potentiated the effects of isoprenaline as shown by the shift to the left of the concentration‐response curve to isoprenaline. Sodium nitroprusside‐induced relaxation was not modified by either drug.
These results show that rolipram is a potent relaxant of the human isolated bronchus, potentiating the effects of β‐adrenoceptor stimulation and suggest that, as previously demonstrated in other species (guinea‐pig, cow) (Tomkinson et al., 1993), there may be a connection between the β2‐adrenoceptor subtype, which predominate in human airway smooth muscle, and the cyclic AMP phosphodiesterase type IV.
Thiocyanate ions selectively antagonize AMPA‐evoked responses in Xenopus laevis oocytes microinjected with rat brain mRNA
Authors: Bowie Derek , Smart Trevor G. 
Published: July 2012

Responses to kainate (KA), willardiine and α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionic acid (AMPA) were recorded from rat brain mRNA‐injected Xenopus laevis oocytes by use of a two‐electrode voltage clamp.
Thiocyanate (SCN−; 50 μm − 4 mm) ions reversibly and selectively inhibited the membrane current responses to AMPA in a non‐competitive manner without affecting KA or willardiine‐induced responses.
The inhibition of AMPA‐induced responses by SCN− was dependent on the SCN− concentration with an estimated IC50 of 1 mm. The antagonism was not dependent on the AMPA concentration.
The response to a high concentration of AMPA (100–200 μm) exhibited a peak inward current which declined to a steady‐state. SCN− inhibited the steady‐state current more than the peak response. The inhibition was unaffected by prior incubation with concanavalin‐A (Con‐A; 10 μm).
Responses to KA were antagonized by AMPA in a competitive manner, suggesting that both agonists may activate a common receptor‐channel complex. This interaction between two non‐NMDA agonists was not affected by the SCN−‐induced inhibition of the AMPA response.
AMPA‐induced responses recorded from large cultured cerebellar neurones by whole‐cell recording were also inhibited by SCN− in a non‐competitive manner. The AMPA‐induced peak current was less affected than the steady‐state response.
We conclude that SCN− can inhibit the response to AMPA in expressed non‐NMDA receptors in Xenopus oocytes and also in native receptors in cultured cerebellar neurones. One possible mechanism of action for SCN− inhibition of responses to AMPA may involve a Con‐A‐insensitive, non‐NMDA receptor‐mediated desensitization.
Inhibition by nitric oxide‐donors of human polymorphonuclear leucocyte functions
Authors: Moilanen E. , Vuorinen P. , Kankaanranta H. , Metsä‐Ketelä T. , Vapaatalo H. 
Published: July 2012

The study was designed to test the hypothesis that nitric oxide (NO)‐releasing compounds increase guanosine 3′:5′‐cyclic monophosphate (cyclic GMP) production in human polymorphonuclear leucocytes (PMNs) and concomitantly inhibit PMN functions, i.e. leukotriene B4 (LTB4) synthesis, degranulation, chemotaxis and superoxide anion (O2−) release. The effects of two new NO‐releasing compounds, GEA 3162 and GEA 5024 were compared to 3‐morpholino‐sydnonimine (SIN‐1) and S‐nitroso‐N‐acetyl‐penicillamine (SNAP).
GEA 3162 and GEA 5024 (1–100 μm) inhibited Ca ionophore A23187‐induced LTB4 and β‐glucuronidase release, chemotactic peptide FMLP‐induced chemotaxis and opsonized zymosan‐triggered chemiluminescence dose‐dependently in human PMNs. SIN‐1 and SNAP were weaker inhibitors.
Cellular cyclic GMP production was increased after exposure to NO‐donors concomitantly with the inhibition of PMN functions. No alterations in the levels of adenosine 3′:5′‐cylic monophosphate (cyclic AMP) were detected.
The results suggest that NO, possibly through increased cyclic GMP, inhibits the activation of human PMNs and may thus act as a local modulator in inflammatory processes.
3,4 Dichlorobenzamil‐sensitive, monovalent cation channel induced by palytoxin in cultured aortic myocytes
Authors: Van Renterghem Catherine , Frelin Christian 
Published: July 2012

Smooth muscle cells were dispersed from rat aorta and then cultured. The action of palytoxin on rat aortic myocytes was analysed by measurement of 22Na+ uptake and single channel recording techniques.
Palytoxin induced an increase in 22Na+ uptake, with a concentration of 50 nm producing half‐maximal activation. The action of palytoxin was inhibited by amiloride derivatives and by ouabain. The concentrations of inhibitor producing half‐maximal inhibition were 10 μm for 3,4 dichlorobenzamil, 30 μm for benzamil, 100 μm for phenamil and 1 mm for ouabain.
In outside‐out patches, palytoxin induced single channel currents that reversed near 0 mV with NaCl or KCl in the extracellular solution, but were outward with N‐methyl‐d‐glucamine chloride or CaCl2 (110 mm), indicating that palytoxin induced a cation channel permeable to Na+ and K+ (PK/PNa = 1.2) but not to Ca2+ (PK/PCa > 30) or to N‐methyl‐d‐glucamine (NMDG) (PK/PNMDG > 11). The unit channel conductance was 11–14 pS.
A high (> 0.1 mm) extracellular concentration of Ca2+ was necessary to observe channel activation by palytoxin. A high (150 mm) extracellular concentration of K+ partially prevented and reversed channel activation by palytoxin.
The channel activity was fully blocked by 3,4 dichlorobenzamil (20 μm) and partially blocked by phenamil (50 μm). It was not reduced by ouabain (200 μm).
Enhancement by endothelin‐1 of microvascular permeability via the activation of ETA receptors
Authors: Filep János G. , Sirois Martin G. , Földes‐Filep Éva , Rousseau Anne , Plante Gérard E. , Fournier Alain , Yano Mitsuo , Sirois Pierre 
Published: July 2012

The objective of the present experiments was to assess the involvement of endothelin‐A (ETA) receptors in mediating the effects of endothelin‐1 on microvascular permeability in conscious rats.
Bolus injection of endothelin‐1 (0.1 and 1 nmol kg−1, i.v.) resulted in a dose‐dependent prolonged pressor effect preceded by a transient depressor response. These changes were accompanied by a dose‐dependent loss of plasma volume. Endothelin‐1 (1 nmol kg−1) enhanced the vascular permeability of the upper and lower bronchi, kidney, stomach, duodenum and spleen (up to 270%) as measured by the extravasation of Evans blue dye.
Pretreatment of the animals with the selective ETA receptor antagonist, BQ‐123 (1 mg kg−1, i.v.) significantly blunted the pressor response to endothelin‐1 without affecting the depressor response. BQ‐123 inhibited by 87% the endothelin‐1 (1 nmol kg−1)‐induced plasma volume loss. BQ‐123 markedly attenuated protein extravasation elicited by endothelin‐1 in the upper and lower bronchi and kidney, whereas it completely inhibited the permeability effect of endothelin‐1 in the stomach and duodenum. BQ‐123 by itself had no significant effect on the parameters studied.
The endothelin‐1 analogue, [Trp(For)21]‐endothelin‐1, in which Trp21 is formylated, was as potent a pressor agent as endothelin‐1, but had no depressor action. Bolus injection of [Trp(For)21]‐endothelin‐l (0.1 and 1 nmol kg−1, i.v.) evoked similar plasma volume losses to those observed following administration of equimolar doses of endothelin‐1. Furthermore, 1 nmol kg−1 [Trp(For)21]‐endothelin‐l evoked increases in protein extravasation similar to endothelin‐1, 1 nmol kg−1.
The present findings suggest that endothelin‐1 enhances microvascular permeability, in part, via the activation of ETA receptors.
Selective inactivation of muscarinic M2 and M3 receptors in guinea‐pig ileum and atria in vitro
Authors: Eglen R.M. , Harris G.C. 
Published: July 2012

The role of muscarinic M2 and M3 receptors in ileal smooth muscle has been evaluated by use of selective receptor alkylation. The alkylating agents, 4‐diphenylacetoxy‐N‐(2‐chloroethyl)‐piperidine (4‐DAMP mustard) was studied for effects against (+)‐cis‐dioxolane, at muscarinic M2 and M3 receptors in guinea‐pig atria or ileum, respectively. 4‐DAMP mustard (10 nm, 40 min exposure) did not discriminate between these muscarinic receptors. In ileum, 4‐DAMP mustard, at 100 nm, resulted in a large dextral shift (197 fold) and depression in maxima. In atria there was a smaller dextral shift (14 fold) but no depression in maxima.
The muscarinic antagonists, atropine (non‐selective), methoctramine (M2‐selective) and para‐fluoro‐hexahydro‐siladiphenidol (pFHHSiD; M3 selective) were studied in protection studies against alkylation by phenoxybenzamine. Washout studies following equilibration of the tissues with atropine (30 nm), methoctramine (0.3 μm) or pFHHSiD (3 μm), showed the compounds to be reversible. No temporal changes in sensitivity to (+)‐cis‐dioxolane were observed.
Exposure, for 20 min, of atria and ileum to phenoxybenzamine (3 and 10 μm respectively) caused dextral shifts and depressions in the maxima of the concentration‐response curve to (+)‐cis‐dioxolane. These effects were inhibited by prior equilibration with atropine (30 nm) and methoctramine (0.1 μm) in atria or atropine (30 nm) and pFHHSiD (3 μm) in ileum. Similar results in ileum were obtained when pilocarpine was used as the agonist.
These data were consistent with muscarinic M2 receptors mediating responses in atria and M3 receptors mediating responses in ileum. No evidence was provided for a direct role of muscarinic M2 receptors in ileal contraction.
It is concluded that receptor protection by reversible antagonists for muscarinic M2 or M3 receptors provides a means to isolate pharmacologically a single subtype in a tissue possessing heterogeneous populations. This technique may prove useful in defining the role of the respective subtypes in smooth muscle contraction.