bluuebunny/crossref_metadata_2025_split huggingface dataset:
NPC 15669‐modulated human polymorphonuclear neutrophil functional responsiveness: effects on receptor‐coupled signal transduction
Authors: Smith Robert J. , Justen James M. , Bleasdale John E. , Sly Laurel M. 
Published: July 2012

The effect of NPC 15669, N‐carboxy‐L‐leucine, N‐[(2,7‐dimethylfluoren‐9‐yl)methyl]ester), an inhibitor of human polymorphonuclear neutrophil (PMN) adhesion, on granule exocytosis and the oxidative burst was investigated in PMN activated with receptor‐specific pathophysiological stimuli.
NPC 15669 caused a concentration‐dependent (1–30 μm) inhibition of the extracellular release of azurophil (myeloperoxidase) and specific (vitamin B12‐binding protein) granule constitutents from PMN exposed to N‐formyl‐methionyl‐leucyl‐phenylalanine (FMLP), leukotriene B4 (LTB4), platelet activating factor (PAF), C5a and interleukin‐8 (IL‐8).
The receptor agonist‐triggered PMN oxidative burst, measured as superoxide anion (O‐2) production, was suppressed by NPC 15669.
Phorbol myristate acetate (PMA)‐stimulated degranulation and O‐2) production were unaffected by NPC 15669.
NPC 15669 (0.1–10 μm) inhibited receptor‐triggered inositol 1,4,5‐trisphosphate (IP3) production and the IP3‐triggered increase in cytosolic‐free calcium ([Ca2+] I) in FMLP‐activated PMN, but not in cells exposed to the other receptor agonists.
NPC 15669 suppressed FMLP but not PMA‐stimulated redistribution of protein kinase C (PKC) in PMN.
The specific binding of [3H]‐FMLP but not [125I]‐C5a to PMN was inhibited by NPC 15669.
NPC 15669 suppressed O‐2 production and the rise in [Ca2+]i in PMN treated with the guanine nucleotide‐binding protein (G‐protein) activators, sodium fluoride (NaF) and mastoparan, respectively.
The results show that NPC 15669 inhibits PMN responsiveness to various receptor agonists, and suggest interference with receptor‐coupled signal transduction in this inflammatory cell at both the receptor and post‐receptor level in a stimulus‐specific manner.
Mechanism of action of the inhibitory effect of nifedipine on the growth of cultured aortic cells from spontaneously hypertensive and normotensive rats
Authors: Hérembert Thierry , Zhu Ding‐Liang , Marche Pierre 
Published: July 2012

To gain insight into the parameters which control vascular structure, we investigated the mechanisms whereby nifedipine, and other dihydropyridines, inhibit the growth of cultured fibroblasts isolated from the adventitia of the aorta of spontaneously hypertensive (SHR) and normotensive Wistar Kyoto (WKY) rats.
The effects of nifedipine on cell proliferation and on serum‐induced DNA synthesis were determined by measuring the cell number and the incorporation of [3H]‐thymidine, respectively. The mechanism of action of nifedipine was studied by adding the drug either to randomly growing cells or to quiescent, G0/G1 arrested and synchronized cells. The effects of varying the duration of drug treatment were also examined.
In randomly growing cultures nifedipine, like other dihydropyridines concentration‐dependently inhibited cell proliferation; the rank order of effect (measured at a concentration of 10 μm) was nifedipine> nisoldipine> nitrendipine∼ nimodipine.
In G0/G1 arrested cell cultures, nifedipine concentration‐dependently inhibited serum‐induced [3H]‐thymidine incorporation. In this respect it had similar effects in cell cultures from WKY and SHR. In both SHR and WKY cultures, nifedipine delayed the transition from G0/G1 to S phase, and inhibited serum‐induced DNA synthesis possibly by acting on the early G1 phase.
In cell cultures from both SHR and WKY, serum‐induced DNA synthesis was similarly (∼40%) inhibited after a 1 day treatment with 10 μm nifedipine. In contrast, after 5 days treatment with the drug, the inhibition of DNA synthesis was ∼65% and ∼10% in SHR and WKY cultures, respectively. The inhibitory effects of nifedipine against proliferation of fibroblasts were ∼25% and 60%, respectively, after 1 and 5 days of treatment, and were similar in cells derived from SHR and WKY. This indicates that 5 days treatment with nifedipine inhibited the proliferation of SHR and WKY fibroblasts by acting mostly on the early G1 phase and the m phase, respectively.
Irrespective of the duration of treatment (1 or 5 days) with 10 μm nifedipine, the inhibition of DNA synthesis could be abolished and partially reduced by Bay K 8644 (1 μm) in WKY and SHR fibroblasts, respectively. In cell cultures from both SHR and WKY the inhibitory effects of a short term and of a long term treatment with nifedipine against cell proliferation were reduced and unaffected, respectively by Bay K 8644.
These results indicate that nifedipine inhibited cell proliferation and serum‐induced DNA synthesis by altering the cell cycle through different mechanisms in SHR and WKY fibroblasts. They also suggest the existence in aortic fibroblasts of interactions between calcium channel blockers of the dihydropyridine series and the mitogenic signalling pathways of growth factors contained in serum.
Effects of 8‐bromo cyclic GMP and verapamil on depolarization‐evoked Ca2+ signal and contraction in rat aorta
Authors: Salomone Salvatore , Morel Nicole , Godfraind Théophile 
Published: July 2012

The pharmacological action of NO donors is usually attributed to a cellular rise in guanosine 3′:5′‐cyclic monophosphate (cyclic GMP), but this hypothesis is based only on indirect evidence. Therefore, we have studied the effects of cyclic BMP on Ca2+ movements and contraction in rat isolated endothelium‐denuded aorta stimulated by KC1 depolarizing solution using the permeant analogue 8‐bromo cyclic BMP (BrcGMP). Isometric contraction and fura‐2 Ca2+ signals were measured simultaneously in preparations treated with BrcGMP and with verapamil. The activation of calcium channels was estimated by measuring the quenching rate of the intracellular fura‐2 signal by Mn2+ and by the depolarization‐dependent influx of 45Ca2+.
Stimulation with 67 mM KCl‐solution evoked an increase in cytosolic Ca2+ concentration ([Ca2+]cyt) and a contractile response which were inhibited by pretreatment with verapamil (0.1 μm) or BrcGMP (0.1‐1 mM). However, the inhibition of the fura‐2 Ca2+ signal was significantly higher with verapamil than with BrcGMP, whereas the contraction was inhibited to a similar extent.
When preparations were exposed to K+‐depolarizing solution in which the calcium concentration was cumulatively increased, the related increase in fura‐2 Ca2+ signal was barely affected by BrcGMP, whereas the contractile tension was strongly and significantly inhibited.
Cellular Ca2+ changes were also estimated with 45Ca2+. 45Ca2+ influx in resting preparations was significantly reduced by BrcGMP (0.1 mM) but not by verapamil (0.1 μm); 45Ca2+ influx in KC1‐depolarized preparations was reduced by verapamil but was unaffected by BrcGMP.
Measurements of Mn2+‐induced quenching of the intracellular fura‐2 signal showed that BrcGMP did not affect divalent cation entry in K+‐stimulated preparations, whereas verapamil concentration‐dependently inhibited Mn2+ entry stimulated by K+‐depolarization.
The present results indicate that BrcGMP did not affect voltage‐dependent Ca2+ channel gating in the rat aorta. For a given fura‐2 Ca2+ signal, the contraction was lower in preparations exposed to BrcGMP than in the untreated ones, suggesting that the activation of cyclic GMP‐dependent kinases reduced the contractile efficacy of calcium. Furthermore, the reduction of depolarization‐dependent 45Ca2+ uptake reported with sodium nitroprusside, a NO donor, was not observed with biologically active concentrations of BrcGMP, suggesting that this drug could have additional mechanisms of action, unrelated to activation of protein G‐kinase.
Prevention by blockade of angiotensin subtype1‐receptors of the development of genetic hypertension but not its heritability
Authors: Madeddu Paolo , Anania Vittorio , Varoni Maria Vittoria , Parpaglia Paolo Pinna , Demontis Maria Piera , Fattaccio Maria Caterina , Palomba Domenico , Pollock David , Glorioso Nicola 
Published: July 2012

We determined whether early inhibition of angiotensin II subtype1 (AT1) receptors by the newly synthesized nonpeptidic antagonist, A‐81988, can attenuate the development of hypertension in spontaneously hypertensive rats (SHR) and if the altered blood pressure phenotype can be passed on to the subsequent generation, not exposed to the antagonist.
Pairs of SHR were mated while drinking tap water or A‐81988 in tap water, and the progeny was maintained on the parental regimen until 14 weeks of age. At this stage, A‐81988‐treated rats showed lower systolic blood pressure and body weight values (136 ±5 versus 185 ±4 mmHg and 247 ±4 versus 283±4 g in controls, P<0.01), while heart rate was similar. In addition, mean blood pressure was reduced (101 ±7 versus 170 ±7 mmHg in controls, P < 0.01), and the pressor responses to intravenous or intracerebroventricular angiotensin II were inhibited by 27 and 59%, respectively. Heart/body weight ratio was smaller in A‐81988‐treated rats (3.2±0.1 versus 3.8±0.1 in controls, P<0.01).
The antihypertensive and antihypertrophic effect of A‐81988 persisted in rats removed from therapy for 7 weeks (systolic blood pressure: 173 ±4 versus 220 ±4 mmHg, heart/body weight ratio: 3.4 ±0.1 versus 4.1 ±0.1 in controls at 21 weeks of age, P < 0.01 for both comparisons), whereas the cardiovascular hypertensive phenotype was fully expressed in the subsequent generation that was maintained without treatment.
These results indicate that chronic blockade of angiotensin AT1‐receptors attenuates the development of hypertension in SHR but it does not prevent the transmission of hypertension to the following generation. Thus, heritability of the SHR's hypertensive trait is not affected by pharmacological manipulation of the cardiovascular phenotype.
Reduction of inflammation and pyrexia in the rat by oral administration of SDZ 224‐015, an inhibitor of the interleukin‐1β converting enzyme
Authors: Elford P.R. , Heng R. , Révész L. , MacKenzie A.R. 
Published: July 2012

The aim of this study was to determine whether a synthetic inhibitor of the interleukin‐1β converting enzyme (ICE) displays oral activity in models of inflammation.
To this end, the ICE inhibitor, SDZ 224‐015, was examined in rat paw oedema, pyrexia and nociception tests.
SDZ 224‐015 (0.3–300 μg kg−1) potently reduced carrageenin‐induced paw oedema, with an oral ED50 of approximately 25 μg kg−1. This effect was independent of endogenous glucocorticoid, as shown by retention of activity upon adrenalectomy.
Pyrexia induced by lipopolysaccharide (0.1 mg kg−1 s.c.) or by interleukin‐1β (100 ng i.v.) was also reduced, over a similar dose‐range to oedema (oral ED50S 11 μg kg−1 and 4 μg kg−1 respectively).
SDZ 224‐015 (0.2–5 mg kg−1, p.o.) displayed analgesic activity in the Randall‐Selitto yeast‐inflamed paw pressure test, significant at a dose of 1 mg kg−1, p.o. 6 Thus, SDZ 224‐015 has potent oral activity in several acute models for inflammation, suggesting that ICE inhibitors may constitute a novel type of anti‐inflammatory agent.
Regional haemodynamic effects of μ‐, δ‐, and κ‐opioid agonists microinjected into the hypothalamic paraventricular nuclei of conscious, unrestrained rats
Authors: Bachelard Hélène , Pître Maryse 
Published: July 2012

The cardiovascular effects of bilateral injection into the hypothalamic paraventricular nuclei of selective μ‐, δ‐, and κ‐opioid receptor agonists were investigated in conscious, unrestrained Wistar Kyoto rats, chronically instrumented with pulsed Doppler flow probes for measurement of regional haemodynamics.
The selective μ‐agonist [D‐Ala2, MePhe4, Gly5ol]enkephalin (DAMGO), injected bilaterally into the hypothalamic paraventricular nuclei (0.01‐1.0 nmol), caused increases in blood pressure, tachycardias, vasoconstriction in renal and superior mesenteric vascular beds and substantial vasodilatation in the hindquarter vascular bed.
The administration of increasing doses (0.01–5.0 nmol) of the selective δ‐agonist [D‐Phe2,5]enkephalin (DPDPE) or the selective κ‐agonist, U50488H into the paraventricular nuclei (PVN) had no significant effect on blood pressure, heart rate, or regional haemodynamics.
Together, the present results are further evidence of a role for opioid peptides, especially acting at μ‐receptors in the PVN, in the central regulation of the cardiovascular system, whereas a role for opioid peptides, acting at δ‐ and κ‐receptors in the PVN, seems less obvious from the present results.
Characterization of the receptors and mechanisms involved in the cardiovascular actions of sCCK‐8 in the pithed rat
Authors: Gaw Alasdair J. , Hills David M. , Spraggs Colin F. 
Published: July 2012

The cardiovascular actions of cholecystokinin and related peptides were investigated in the pithed rat. The receptors and the mechanisms involved in these experiments were characterized.
Sulphated cholecystokinin octapeptide (sCCK‐8, 0.1–100 nmol kg−1, i.v.) elicited a dose‐dependent bradycardia and increase in mean arterial blood pressure. Neither gastrin‐17 nor pentagastrin had any effect at concentrations up to 100 nmol kg−1.
Both the pressor response and bradycardia elicited by sCCK‐8 were reduced by the selective CCKA receptor antagonists, devazepide (0.5–50 nmol kg−1) and lorglumide (1–7 μmol kg−1). The selective CCKB receptor antagonists, CI‐988 (1 μmol kg−1) and L‐365,260 (15 μmol kg−1) did not inhibit the effects of sCCK‐8.
The pressor response induced with sCCK‐8 was reduced by treatment with either phentolamine (3 μmol kg−1) or guanethidine (2 μmol kg−1) and was unaffected by treatment with propranolol, atropine or hexamethonium. The pressor response also persisted following bilateral adrenalectomy.
The bradycardia induced with sCCK‐8 was unaffected by treatment with phentolamine, propranolol, guanethidine, atropine, hexamethonium or bilateral adrenalectomy.
The tetrapeptide of cholecystokinin (CCK‐4) elicited a dose‐dependent pressor response but did not induce bradycardia. The pressor response was unaffected by devazepide (50 nmol kg−1), L‐365260 (15 μmol kg−1) or phentolamine (3 μmol kg−1).
In the pithed rat, sCCK‐8 acted via CCKA receptors to increase arterial blood pressure indirectly, at least in part, through activation of α‐adrenoceptors. The observed bradycardia was also mediated by CCKA receptors but possibly through a direct action on the heart.
Comparison of the interaction of agmatine and crude methanolic extracts of bovine lung and brain with α2‐adrenoceptor binding sites
Authors: Pinthong D. , Hussain J.F. , Kendall D.A. , Wilson V.G. 
Published: July 2012

In the present study we have evaluated whether α2‐adrenoceptor binding sites on bovine cerebral cortex membranes labelled by [3H]‐clonidine, [3H]‐idazoxan and [3H]‐RX‐821002 can distinguish between known agonists and antagonists. This model has then been used to compare the binding profiles of the putative non‐catecholamine, clonidine‐displacing substance (CDS), agmatine and crude methanolic extracts of bovine lung and brain.
Saturation studies carried out in the presence and absence of noradrenaline, 10 μmol l−1, revealed that the maximum number of binding sites on bovine cerebral cortex membranes for [3H]‐idazoxan and [3H]‐RX‐821002 were approximately 60–80% greater than those for [3H]‐clonidine (62.6 fmol mg−1 protein). Rauwolscine, the selective α2‐adrenoceptor antagonist, was approximately 100 fold more potent against each of the ligands than the selective α1adrenoceptor diastereoisomer, corynanthine. Also, the pKi value for the selective α1‐adrenoceptor prazosin against each ligand was less than 6.
Adrenaline, UK‐14034, rauwolscine, corynanthine, RX‐811059 and prazosin produced concentration‐dependent inhibition of binding of all three 3H‐ligands. The agonists, adrenaline and UK‐14304, were approximately 5 and 10 fold less potent against [3H]‐idazoxan and [3H]‐RX‐821002, respectively, than against [3H]‐clonidine. In marked contrast, the antagonists, rauwolscine, corynanthine, RX‐811059 and prazosin exhibited a different profile, being approximately 2–3 fold more potent against sites labelled by [3H]‐RX‐821002 and [3H]‐idazoxan compared to sites labelled by [3H]‐clonidine.
Agmatine and histamine produced a concentration‐dependent displacement of [3H]‐clonidine, [3H]‐idazoxan and [3H]‐RX‐821002 binding to bovine cerebral cortex membranes. The pKi values for agmatine and histamine were independent of the 3H‐ligand employed, approximately 4.8 and 4.5, respectively.
Crude methanolic extracts of bovine brain and lung produced a concentration‐dependent inhibition of [3H]‐clonidine binding to bovine cerebral cortex membranes (>90%). Based on the volume of the extract that caused 50% inhibition of [3H]‐clonidine binding, bovine lung contains 3 fold more CDS than bovine brain. Both extracts were at least 5 fold more potent against α2‐adrenoceptor sites labelled by [3H]‐clonidine than those labelled by [3H]‐idazoxan and [3H]‐RX‐821002.
All three 3H‐ligands label the same population of α2‐adrenoceptor binding sites on bovine cerebral cortex membranes, but [3H]‐clonidine appears to label selectively the ‘agonist’ state of the sites: for which known agonists, adrenaline and UK‐14304, exhibit a higher affinity. Our results indicate that neither agmatine nor histamine can account for the CDS activity present in crude extracts of bovine brain and lung. Moreover, these extracts appear to possess a binding profile similar to that of adrenaline and UK‐14304, suggesting that they may possess agonist activity.
Effect of frusemide, ethacrynic acid and indanyloxyacetic acid on spontaneous Ca‐activated currents in rabbit portal vein smooth muscle cells
Authors: Greenwood I.A. , Hogg R.C. , Large W.A. 
Published: July 2012

The effect of frusemide, ethacrynic acid and indanyloxyacetic acid was investigated on spontaneous calcium‐activated chloride (IC1(ca)) and potassium currents (IK(ca)) in rabbit portal vein cells with the perforated patch technique.
Frusemide (0.3‐1.10 × 10−3 m) reduced the amplitude of spontaneous transient inward chloride currents (STICs) in a concentration‐dependent manner. The degree of inhibition on STIC amplitude was similar between —50 and +30 mV and frusemide did not alter the STIC reversal potential (Erev).
The voltage‐dependent exponential decay of STICs, which is thought to represent closure of chloride channels, was not altered by frusemide.
The amplitude and frequency of spontaneous potassium outward currents (STOCs) were not altered by frusemide. Since both STICs and STOCs are activated by calcium released from intracellular stores these data indicate that frusemide may block directly IC1(ca).
Ethacrynic acid (2–5 × 10−4m) decreased the amplitude of STICs in a concentration‐dependent manner by a similar amount at potentials of — 50 to + 30 mV but did not alter the STIC Erev. However, these concentrations of ethacrynic acid also reduced STOC amplitude and 5 × 10−4 m ethacrynic acid evoked a sustained outward current in most cells at 0 mV; thus ethacrynic acid has a more complex action than simple block of Ic1(Ca).
Indanyloxyacetic acid reduced both STIC amplitude and decay time without affecting STOCs and thus also seems to inhibit directly Ic1(ca). It is discussed whether block of IC1(ca) mediates the vasodilator effect of these agents.
D‐Cycloserine transport in human intestinal epithelial (Caco‐2) cells: mediation by a H + ‐coupled amino acid transporter
Authors: Thwaites David T. , Armstrong Gillian , Hirst Barry H. , Simmons Nicholas L. 
Published: July 2012

The ability of D‐cycloserine to act as a substrate for H+/amino acid symport has been tested in epithelial layers of Caco‐2 human intestinal cells.
In Na+‐free media with the apical bathing media held at pH 6.0, D‐cycloserine (20 mM) is an effective inhibitor of net transepithelial transport (Jnet) of L‐alanine (100 μm) and its accumulation (across the apical membrane) in a similar manner to amino acid substrates (L‐alanine, β‐alanine, L‐proline and glycine). In contrast L‐valine was ineffective as an inhibitor for H+/amino acid symport. Both inhibition of L‐alanine Jnet and its accumulation by D‐cycloserine were dose‐dependent, maximal inhibition being achieved by 5–10 mM.
Both D‐cycloserine and known substrates for H+/amino acid symport stimulated an inward short circuit current (Isc) when voltage‐clamped monolayers of Caco‐2 epitheha, mounted in Ussing chambers, were exposed to apical substrate in Na+‐free media, with apical pH held at 6.0. The D‐cycloserine dependent increase in Isc was dose‐dependent with an apparent Km= 15.8 + 2.0 (mean ± s.e.mean) mM, and Vmax = 373±21 nmol cm−2 h−1.
D‐Cycloserine (20 mM) induced a prompt acidification of Caco‐2 cell cytosol when superfused at the apical surface in both Na+ and Na+‐free conditions. Cytosolic acidification in response to D‐cycloserine was dependent upon superfusate pH, being attenuated at pH 8 and enhanced in acidic media.
The increment in Isc with 20 mM D‐cycloserine was non‐additive with other amino acid substrates for H+/amino acid symport.
The enantiomers of zacopride: an intra‐species comparison of their potencies in functional and anxiolytic models
Authors: Bill David J. , Coleman James , Hallett Ian , Middlefell Vicki C. , Rhodes Keith F. , Fletcher Allan 
Published: July 2012

The 5‐HT3 receptor antagonist, zacopride, and its enantiomers, R(+)‐zacopride and S(−)−zacopride, were examined in three pharmacological models: (i) 5‐HT‐induced depolarizarion of the mouse isolated vagus nerve preparation, (ii) the 5‐HT‐evoked von Bezold‐Jarisch reflex in the mouse, and (iii) the mouse light:dark box model of anxiety. Other standard 5‐HT3 receptor antagonists were also included for comparison in these studies.
Racemic zacopride, and both of the enantiomers, displayed potent 5‐HT3 receptor antagonist activity in the isolated vagus nerve and in the von Bezold‐Jarisch model. No 5‐HT3 receptor agonist or partial agonist effects of these compounds were detected.
In the isolated vagus nerve, R(+)‐zacopride and ondansetron were surmountable 5‐HT3 receptor antagonists (pA2 values of 9.3 and 8.3, respectively), whereas racemic zacopride, S(—)‐zacopride and tropisetron were insurmountable antagonists, markedly suppressing the maximum response to 5‐HT.
In vivo, racemic zacopride, R(+)‐zacopride, S(—)‐zacopride and WAY 100289 were potent antagonists of the 5‐HT‐evoked von Bezold‐Jarisch reflex, with minimum effective doses (lowest dose required to reduce the reflex by ≥85%; MED85) of 1.0, 3.0, 0.3 and 3.0 μg kg−1, s.c, respectively.
Racemic zacopride, R(+)‐zacopride and S(—)‐zacopride were active in the mouse light:dark box model of anxiety, with similar potencies (minimum effective dose 1 μg kg−1, s.c.) and similar active dose‐ranges (1–1000 μg kg−1, s.c).
The doses of racemic zacopride, R(+)‐zacopride and S(−)−zacopride required to block 5‐HT3 receptors in vivo correlated reasonably well with their potencies in an anxiety model within the same species. In these studies, there was no evidence of a marked difference between the anxiolytic potencies of R(+)‐zacopride and S(—)‐zacopride.