bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ginsenosides Rb1 and Re decrease cardiac contraction in adult rat ventricular myocytes: role of nitric oxide
Authors: Scott Glenda I , Colligan Peter B , Ren Bonnie H , Ren Jun 
Published: January 2005

Panax ginseng is used to enhance stamina and relieve fatigue as well as physical stress. Ginsenoside, the effective component of ginseng, regulates cardiovascular function. This study was to examine the effect of ginsenosides Rb1 and Re on cardiac contractile function at the cellular level. Ventricular myocytes were isolated from adult rat hearts and were stimulated to contract at 0.5 Hz. Contractile properties analysed included: peak shortening (PS), time‐to‐90%PS (TPS), time‐to‐90% relengthening (TR90), and fluorescence intensity change (ΔFFI). Nitric oxide synthase (NOS) activity was determined by the 3H‐arginine to 3H‐citrulline conversion assay.
Both Rb1 and Re exhibited dose‐dependent (1 – 1000 nM) inhibition in PS and ΔFFI, with maximal inhibitions between 20 – 25%. Concurrent application Rb1 and Re did not produce any additive inhibition on peak shortening amplitude (with a maximal inhibition of 24.9±6.1%), compared to Rb1 or Re alone. Pretreatment with the NOS inhibitor Nω‐nitro‐L‐arginine methyl ester (L‐NAME, 100 μM) abolished the effect of Rb1 and Re. Both Rb1 and Re significantly (P<0.05) stimulated NOS activity concentration‐dependently.
This study demonstrated a direct depressant action of ginsenosides on cardiomyocyte contraction, which may be mediated in part through increased NO production.

British Journal of Pharmacology (2001) 134, 1159–1165; doi:10.1038/sj.bjp.0704377
Differential regulation of endobiotic‐oxidizing cytochromes P450 in vitamin A‐deficient male rat liver
Authors: Murray Michael , Sefton Rachel M , Croft Kevin D , Butler Alison M 
Published: January 2005

The hepatic CYP4A‐dependent ω‐hydroxylation of arachidonic acid and CYP2C11‐dependent 2α‐/16α‐hydroxylations of testosterone were decreased to 74 and 60% of respective control in microsomal fractions from vitamin A‐deficient rats. Decreases in the rates of arachidonic acid ω‐1‐hydroxylation and testosterone 6β‐, 7α‐ and 17α‐hydroxylations were less pronounced.
Corresponding decreases in microsomal CYP4A and CYP2C11 immunoreactive protein expression to 64 and 68% of respective control were observed in vitamin A‐deficient rat liver. Expression of CYP3A proteins was unchanged from vitamin A‐adequate control.
Northern analysis revealed a selective decrease in CYP4A2 mRNA expression in vitamin A‐deficient rat liver to ∼5% of control; expression of the related CYP4A1/4A3 mRNAs was not decreased. CYP2C11 mRNA expression was also decreased in vitamin A‐deficient male rat liver to 39% of control levels.
Intake of the deficient diet containing all‐trans‐retinoic acid (ATRA) during the final week of the experiment restored CYP4A2 mRNA and CYP4A protein. Administration of exogenous androgen or episodic growth hormone was ineffective. In contrast, CYP2C11 expression was restored by ATRA and androgen, but not by growth hormone.
From these studies it emerges that CYP4A2, a fatty acid ω‐hydroxylase in rat liver, is highly dependent on vitamin A for optimal expression, whereas CYP2C11 is indirectly down regulated by androgen deficiency resulting from vitamin A‐deficiency. Altered CYP expression in vitamin A‐deficiency provides insights into the relationship between dietary constituents and the intracellular formation of vasoactive eicosanoids as well as the clearance of androgenic steroids.

British Journal of Pharmacology (2001) 134, 1487–1497; doi:10.1038/sj.bjp.0704380
Protamine augments stretch induced calcium increase in vascular endothelium
Authors: Murase Kichiro , Naruse Keiji , Kimura Akira , Okumura Kenji , Hayakawa Tetsuo , Sokabe Masahiro 
Published: January 2005

Human umbilical vein endothelial cells cultured on a transparent silicone chamber were subjected to a short stretch pulse (ca. 1 s, 5 – 25% stretch) of their substrate and following increases in intracellular Ca2+ concentration ([Ca2+]i) were measured by fluorescence intensity ratiometry using fura‐2.
In response to mechanical stretch, the cells in HEPES buffered saline exhibited a Ca2+ transient in a dose dependent way. The response was completely dependent on external Ca2+ and inhibited by gadolinium (Gd3+), suggesting that it was mediated by the activation of a stretch activated cation channel (SACatC).
Interestingly, the stretch induced Ca2+ transient was significantly augmented in the presence of basic polypeptide, protamine. This augmented Ca2+ response was inhibited neither by Gd3+ nor by the deprivation of external Ca2+, indicating that the SACatC is not responsible for this phenomenon.
In contrast, this augmentation was inhibited by depletion of intracellular Ca2+ stores with thapsigargin or by the pretreatment with phospholipase inhibitors such as U73122 and manoalide.
These results suggest the presence of a metabotropic mechanoreceptor distinct from the SACatC in vascular endothelium. This augmented [Ca2+]i increase may contribute to the vasodilating response induced by protamine during heparin neutralization in cardiac surgery.

British Journal of Pharmacology (2001) 134, 1403–1410; doi:10.1038/sj.bjp.0704386
Evidence of P‐glycoprotein mediated apical to basolateral transport of flunisolide in human broncho‐tracheal epithelial cells (Calu‐3)
Authors: Florea Bogdan I , Van Der Sandt Inez C J , Schrier S Mariette , Kooiman Klazina , Deryckere Koen , De Boer Albertus G , Junginger Hans E , Borchard Gerrit 
Published: January 2005

Transepithelial transport of flunisolide was studied in reconstituted cell monolayers of Calu‐3, LLC‐PK1 and the MDR1‐P‐glycoprotein transfected LLC‐MDR1 cells.
Flunisolide transport was polarized in the apical (ap) to basolateral (bl) direction in Calu‐3 cells and was demonstrated to be ATP‐dependent. In LLC‐MDR1 cells, flunisolide was transported in the bl to ap direction and showed no polarization in LLC‐PK1 cells.
Non‐specific inhibition of cellular metabolism at low temperature (4°C) or by 2‐deoxy‐D‐glucose (2‐d‐glu) and sodium azide (NaN3) abolished the polarized transport. Polarized flunisolide transport was also inhibited by the specific Pgp inhibitors verapamil, SDZ PSC 833 and LY335979.
Under all experimental conditions and in the presence of all used inhibitors, no decrease in the TransEpithelial Electrical Resistance (TEER) values was detected. From all inhibitors used, only the general metabolism inhibitors 2‐deoxy‐D‐glucose and NaN3, decreased the survival of Calu‐3 cells.
Western blotting analysis and confocal laser scanning microscopy demonstrated the presence of MDR1‐Pgp at mainly the basolateral side of the plasma membrane in Calu‐3 cells and at the apical side in LLC‐MDR1 cells. Mass spectroscopy studies demonstrated that flunisolide is transported unmetabolized across Calu‐3 cells.
In conclusion, these results show that the active ap to bl transport of flunisolide across Calu‐3 cells is facilitated by MDR1‐Pgp located in the basolateral plasma membrane.

British Journal of Pharmacology (2001) 134, 1555–1563; doi:10.1038/sj.bjp.0704390
Evidence for two endothelin EtA receptor subtypes in rabbit arteriolar smooth muscle
Authors: Curtis Tim M , Scholfield C Norman 
Published: January 2005

Effects of endothelin‐1 (Et‐1) were studied on membrane currents in choroidal arteriolar smooth muscle by using perforated patch‐clamp recordings.
Et‐1 (10 nM) activated oscillatory Ca2+‐activated Cl−‐currents (ICl(Ca)) which could not be reversed by washing out.
Currents through L‐type Ca2+ channels were resolved in a divalent free medium (ICa(L)Na). Et‐1 reduced ICa(L)Na by 75±7% within 30 s and this effect faded over 5 min, when the depression remained constant. On washing out Et‐1, ICa(L)Na almost completely recovered within 10 s.
BQ123 (1 μM), a peptide EtA receptor blocker, prevented the activation of ICl(Ca), but failed to inhibit ICl(Ca) transients once they had been initiated. In contrast, BQ123 not only prevented but also reversed the inhibition of ICa(L)Na by Et‐1. BQ788 (1 μM), an EtB receptor antagonist, did not prevent the activation of ICl(Ca) or the inhibition of ICa(L)Na by Et‐1.
ABT‐627 (10 nM), a non‐peptide EtA receptor antagonist also blocked the activation of ICl(Ca). However, on ICa(L)Na, ABT‐627 (10 nM) mimicked the action of Et‐1 an effect blocked by BQ123 suggesting that ABT‐627 acted as an agonist.
The data are consistent with choroidal arteriolar smooth muscle cells having two types of EtA receptor, one where BQ123 is an antagonist and ABT‐627 an agonist, where ligands dissociate freely and this receptor is coupled to inhibition of L‐type Ca2+ channels. In the other, BQ123 and ABT‐627 are both antagonists and with Et‐1 the receptor converts to a high affinity state producing the classical irreversible activation ICl(Ca).

British Journal of Pharmacology (2001) 134, 1787–1795; doi:10.1038/sj.bjp.0704393
Detailed characterization of cysteine‐less P‐glycoprotein reveals subtle pharmacological differences in function from wild‐type protein
Authors: Taylor Andrew M , Storm Janet , Soceneantu Loredana , Linton Kenneth J , Gabriel Mark , Martin Catherine , Woodhouse James , Blott Emma , Higgins Christopher F , Callaghan Richard 
Published: January 2005

Subtle alterations in the coupling of drug binding to nucleotide hydrolysis were observed following mutation of all seven endogenous cysteine residues to serines in the human multidrug resistance transporter, P‐glycoprotein. Wild‐type (wt) and the mutant (cys‐less) forms of P‐gp were expressed in Trichoplusia ni (High Five) cells and purified by metal affinity chromatography in order to undertake functional studies.
No significant differences were observed in substrate ([3H]‐azidopine) binding to wt or cys‐less P‐gp. Furthermore, neither the transported substrate vinblastine, nor the modulator nicardipine, differed in their respective potencies to displace [3H]‐azidopine from the wt or cys‐less P‐gp. These results suggest that respective binding sites for these drugs were unaffected by the introduced cysteine to serine substitutions.
The Michaelis‐Menten characteristics of basal ATP hydrolysis of the two isoforms of P‐gp were identical. The maximal ATPase activity in the presence of vinblastine was marginally reduced whilst the Km was unchanged in cys‐less P‐gp compared to control. However, cys‐less P‐gp displayed lower overall maximal ATPase activity (62%), a decreased Km and a lower degree of stimulation (76%) in the presence of the modulator nicardipine.
Therefore, the serine to cysteine mutations in P‐gp may suggest that vinblastine and nicardipine transduce their effects on ATP hydrolysis through distinct conformational pathways. The wt and cys‐less P‐gp isoforms display similarity in their fundamental kinetic properties thereby validating the use of cys‐less P‐gp as a template for future cysteine‐directed structure/function analysis.

British Journal of Pharmacology (2001) 134, 1609–1618; doi:10.1038/sj.bjp.0704400
Modulation of cardiac activity by tachykinins in the rat substantia nigra
Authors: Lessard Andrée , Couture Réjean 
Published: January 2005

The effects of tachykinin NK1, NK2 and NK3 receptor agonists and antagonists were measured on blood pressure (MAP) and heart rate (HR) after bilateral microinjection into the substantia nigra (SN) of awake, unrestrained rats.
Increasing doses (25 pmol – 1 nmol) of selective agonists at NK1 ([Sar9,Met(O2)11]SP), NK2 ([β‐Ala8]NKA(4 – 10)) and NK3 (senktide) receptors into the SN produced tachycardia which was selectively and reversibly blocked by the prior injection of tachykinin antagonists at NK1 (RP67580, 250 pmol), NK2 (SR48968, 250 pmol) and NK3 (R‐820, 500 pmol) receptor. A rapid fall in MAP followed by a pressor response was seen with 1 nmol of [Sar9,Met(O2)11]SP. Behavioural activity was elicited by 1 nmol of [Sar9,Met(O211]SP (sniffing>face washing=grooming) and senktide (sniffing>wet dog shake>rearing=locomotion). Tachykinin antagonists had no direct cardiovascular or behavioural effects.
The tachycardia produced by 100 pmol of [β‐Ala8]NKA(4 – 10) or senktide was abolished by an i.v. treatment with atenolol (β1‐adrenoceptor antagonist, 5 mg kg−1) while that evoked by [Sar9,Met(O2)11]SP was reduced. A combination of atenolol (5 mg kg−1) and atropine (muscarinic antagonist, 1 mg kg−1) blocked the response evoked by [Sar9,Met(O2)11]SP.
These data suggest that the SN is a potential site of modulation of cardiac activity by tachykinins. In addition to the withdrawal of the cardiovagal activity by NK1 receptor, the three tachykinin receptors appear to increase the sympatho/adrenal drive to the heart. This occurs independently of changes in MAP and behaviour. Hence, this study highlights a new central regulatory mechanism of cardiac autonomic activity.

British Journal of Pharmacology (2001) 134, 1749–1759; doi:10.1038/sj.bjp.0704401
Tumour necrosis factor‐alpha and leukotriene B4 mediate the neutrophil migration in immune inflammation
Authors: Canetti C , Silva J S , Ferreira S H , Cunha F Q 
Published: January 2005

We investigated the mediators responsible for neutrophil migration induced by ovalbumin (OVA) in immunized mice and the mechanisms involved in their release.
OVA administration promoted dose‐ and time‐dependent neutrophil migration in immunized, but not in non‐immunized mice, which was mediated by leukotriene B4 (LTB4) and tumour necrosis factor (TNF)α, since it was inhibited by LTB4 synthesis inhibitor (MK 886) or by LTB4 receptor antagonist (CP 105,696), by dexamethasone and by antiserum to TNFα (82, 85, 63 and 87%, respectively). Confirming TNFα involvement, OVA challenge in immunized p55 TNF receptor deficient mice (p55−/−) did not promote neutrophil migration (control: 2.90±0.68; p55−/−: 0.92±0.23×106 neutrophils cavity−1).
OVA‐stimulated peritoneal cells from immunized mice released a neutrophil chemotactic factor which mimicked, in naive mice, neutrophil migration induced by OVA.
Supernatant chemotactic activity is due to TNFα and LTB4, since its release was inhibited by MK 886 (93%) and dexamethasone (90%), and significant amounts of these mediators were detected.
TNFα and LTB4 released by OVA challenge seem to act through a sequential mechanism, since MK 886 inhibited (88%) neutrophil migration induced by TNFα. Moreover, peritoneal cells stimulated with TNFα released LTB4.
CD4+ T cells are responsible for TNFα release, because the depletion of this subset prevented the release of TNFα (control: 400±25; immunized: 670±40; CD4+ depleted: 435±18 pg ml−1).
In conclusion, neutrophil migration induced by OVA depends on TNFα released by CD4+ cells, which acts through an LTB4‐dependent mechanism.

British Journal of Pharmacology (2001) 134, 1619–1628; doi:10.1038/sj.bjp.0704403
Nuclear factor kappa B is involved in lipopolysaccharide‐stimulated induction of interferon regulatory factor‐1 and GAS/GAF DNA‐binding in human umbilical vein endothelial cells
Authors: Liu Li , Paul Andrew , MacKenzie Christopher J , Bryant Clare , Graham Anne , Plevin Robin 
Published: January 2005

In this study we examined the signalling events that regulate lipopolysaccharide (LPS)‐stimulated induction of interferon regulatory factor (IRF)‐1 in human umbilical vein endothelial cells (HUVECs).
LPS stimulated a time‐ and concentration‐dependent increase in IRF‐1 protein expression, an effect that was mimicked by the cytokine, tumour necrosis factor (TNF)‐α.
LPS stimulated a rapid increase in nuclear factor kappa B (NFκB) DNA‐binding activity. Pre‐incubation with the NFκB pathway inhibitors, N‐α‐tosyl‐L‐lysine chloromethyl ketone (TLCK) or pyrrolidine dithiocarbamate (PDTC), or infection with adenovirus encoding IκBα, blocked both IRF‐1 induction and NFκB DNA‐binding activity.
LPS and TNFα also stimulated a rapid activation of gamma interferon activation site/gamma interferon activation factor (GAS/GAF) DNA‐binding in HUVECs. Preincubation with the Janus kinase (JAK)‐2 inhibitor, AG490 blocked LPS‐stimulated IRF‐1 induction but did not affect GAS/GAF DNA‐binding.
Preincubation with TLCK, PDTC or infection with IκBα adenovirus abolished LPS‐stimulated GAS/GAF DNA‐binding.
Incubation of nuclear extracts with antibodies to RelA/p50 supershifted GAS/GAF DNA‐binding demonstrating the involvement of NFκB isoforms in the formation of the GAS/GAF complex.
These studies show that NFκB plays an important role in the regulation of IRF‐1 induction in HUVECs. This is in part due to the interaction of NFκB isoforms with the GAS/GAF complex either directly or via an intermediate protein.

British Journal of Pharmacology (2001) 134, 1629–1638; doi:10.1038/sj.bjp.0704404
Effects of moderate hypothermia on sarcolemmal Na+/H+ exchanger activity and its inhibition by cariporide in cardiac ventricular myocytes
Authors: Hoshino Kimihiko , Avkiran Metin 
Published: January 2005

Specific inhibitors of the sarcolemmal Na+/H+ exchanger (NHE) such as cariporide are being evaluated for cardioprotective therapy during cardiac surgery. We determined the effects of moderate hypothermia (25°C), as occurs during cardiac surgery, on (1) sarcolemmal NHE activity and (2) the NHE‐inhibitory potency of cariporide, in isolated adult rat ventricular myocytes.
As the index of NHE activity, trans‐sarcolemmal acid efflux rate (JH) was determined by microepifluorescence in single cells (n=8 to 11 per group), during recovery from intracellular acidosis in bicarbonate‐free conditions.
Initially, myocytes were subjected to two consecutive acid pulses; these both occurred at 37°C in the normothermic control group but the second pulse was at 25°C in the moderate hypothermia group. JH values obtained after the first pulse were superimposed in both groups, indicating comparable cell populations. However, after the second pulse, JH values in the moderate hypothermia group were approximately 50% of those in the normothermic control group over the pHi range 6.80 – 7.10.
Similar results were obtained in cells subjected to a single acid pulse at 37 or 25°C, with JH values in the latter group measuring approximately 60% of those in the former over the pHi range 6.80 – 7.10.
Cariporide (0.01, 0.03, 0.1, 0.3, 1.0 or 3.0 μM), present during recovery from a single acid pulse, reduced JH in a concentration‐dependent manner, with IC50 values of 150 and 130 nM at 37 and 25°C, respectively.
We conclude that moderate hypothermia produces (1) a significant, but partial, inhibition of sarcolemmal NHE activity, and (2) no significant effect on the NHE‐inhibitory potency of cariporide.

British Journal of Pharmacology (2001) 134, 1587–1595; doi:10.1038/sj.bjp.0704405
DCPIB is a novel selective blocker of ICl,swell and prevents swelling‐induced shortening of guinea‐pig atrial action potential duration
Authors: Decher Niels , Lang Hans J , Nilius Bernd , Brüggemann Andrea , Busch Andreas E , Steinmeyer Klaus 
Published: January 2005

We identified the ethacrynic‐acid derivative DCPIB as a potent inhibitor of ICl,swell, which blocks native ICl,swell of calf bovine pulmonary artery endothelial (CPAE) cells with an IC50 of 4.1 μM. Similarly, 10 μM DCPIB almost completely inhibited the swelling‐induced chloride conductance in Xenopus oocytes and in guinea‐pig atrial cardiomyocytes. Block of ICl,swell by DCPIB was fully reversible and voltage independent.
DCPIB (10 μM) showed selectivity for ICl,swell and had no significant inhibitory effects on ICl,Ca in CPAE cells, on chloride currents elicited by several members of the CLC‐chloride channel family or on the human cystic fibrosis transmembrane conductance regulator (hCFTR) after heterologous expression in Xenopus oocytes. DCPIB (10 μM) also showed no significant inhibition of several native anion and cation currents of guinea pig heart like ICl,PKA, IKr, IKs, IK1, INa and ICa.
In all atrial cardiomyocytes (n=7), osmotic swelling produced an increase in chloride current and a strong shortening of the action potential duration (APD). Both swelling‐induced chloride conductance and AP shortening were inhibited by treatment of swollen cells with DCPIB (10 μM). In agreement with the selectivity for ICl,swell, DCPIB did not affect atrial APD under isoosmotic conditions.
Preincubation of atrial cardiomyocytes with DCPIB (10 μM) completely prevented both the swelling‐induced chloride currents and the AP shortening but not the hypotonic cell swelling.
We conclude that swelling‐induced AP shortening in isolated atrial cells is mainly caused by activation of ICl,swell. DCPIB therefore is a valuable pharmacological tool to study the role of ICl,swell in cardiac excitability under pathophysiological conditions leading to cell swelling.

British Journal of Pharmacology (2001) 134, 1467–1479; doi:10.1038/sj.bjp.0704413
Urocortin relaxes rat tail arteries by a PKA‐mediated reduction of the sensitivity of the contractile apparatus for calcium
Authors: Lubomirov Lubomir , Gagov Hristo , Petkova‐Kirova Polina , Duridanova Dessislava , Kalentchuk Vjatscheslav U , Schubert Rudolf 
Published: January 2005

Urocortin is an endogenous vasodilator although the mechanism of vasorelaxation is not completely understood. The hypothesis that an alteration of smooth muscle calcium concentration is involved was tested using isometric tension recording and calcium fluorimetry. The relationship between contraction and intracellular calcium was also estimated.
Urocortin produced a concentration dependent relaxation (pD2 8.59±0.06, n=6) of vessels pre‐contracted with a physiological salt solution containing 42 mM KCl (42 mM K‐PSS).
Removal of the endothelium did not alter the effect of urocortin, pD2 was 8.49±0.11, n=5.
Corticotropin‐releasing factor relaxed 42 mM K‐PSS pre‐contracted vessels with less potency compared to urocortin (pD2 6.99±0.28, n=5).
Urocortin at 100 nM relaxed vessels pre‐contracted with 42 mM K‐PSS by 59.6±4.6% (n=8) and vessels pre‐contracted with 500 nM noradrenaline by 25.2±6.8% (n=6). Both effects were not accompanied by a change in the intracellular calcium concentration.
Urocortin at 100 nM produced a significant rightward shift of 0.33±0.07 units of normalized intracellular calcium (n=5) of the relationship between tension and intracellular calcium.
The urocortin‐induced relaxation was considerably reduced in the presence of 0.3 mM Rp‐8‐CPT‐cAMPS, a cyclic AMP‐dependent protein kinase (PKA) inhibitor.
The PKA‐activator Sp‐5,6‐DCl‐cBIMPS relaxed 42 mM K‐PSS pre‐contracted vessels (pD2 4.98±0.07, n=6). Sp‐5,6‐DCl‐cBIMPS at 0.1 mM relaxed vessels by 85.3±2.5% (n=5), but did not change the intracellular calcium concentration.
In conclusion, the data show that urocortin is a potent, endothelium‐independent dilator of rat tail arteries and suggest that this effect is mediated by PKA causing a reduction of the sensitivity of the contractile apparatus for calcium.

British Journal of Pharmacology (2001) 134, 1564–1570; doi:10.1038/sj.bjp.0704418