bluuebunny/crossref_metadata_2025_split huggingface dataset:
Role of nitric oxide/cyclic GMP in myocardial adenosine A1 receptor‐inotropic response
Authors: Sterin‐Borda Leonor , Gómez Ricardo M , Borda Enri 
Published: January 2005

In this study we have determined the different signalling pathways involved in adenosine A1‐receptor (A1‐receptor)‐dependent inhibition of contractility in rat isolated atria.
N‐cyclopentyladenosine (CPA) stimulation of A1‐receptor exerts: negative inotropic response, inositol phosphates accumulation, stimulation of nitric oxide synthase (NOS), increased production of nitric oxide (NO) and cyclic GMP.
Inhibitors of phospholipase C (PLC), protein kinase C (PKC), calcium/calmodulin, NOS and guanylate cyclase shifted the dose‐response curve of CPA on contractility to the right. Those inhibitors also attenuated the A1‐receptor‐dependent increase in cyclic GMP and activation of NOS.
These results suggest that CPA activation of A1‐receptors exerts a negative inotropic effect associated with increased production of nitric oxide and cyclic GMP. The mechanism appears to occur secondarily to stimulation of phosphoinositide turnover via PLC activation. This, in turn, triggers cascade reactions involving calcium/calmodulin and PKC, leading to activation of NOS and soluble guanylate cyclase.

British Journal of Pharmacology (2002) 135, 444–450; doi:10.1038/sj.bjp.0704487
Subeffective doses of dexketoprofen trometamol enhance the potency and duration of fentanyl antinociception
Authors: Gaitán Gema , Herrero Juan F 
Published: January 2005

The combination of classic non‐steroidal antiinflammatory drugs (NSAIDs) with opiates induces more analgesia than the summed effect of each drug given separately. No studies have been performed using new generation NSAIDs and fentanyl nor on the duration of this effect.
We have studied the analgesic effect of fentanyl alone and after the administration of subeffective doses of dexketoprofen trometamol in rat nociceptive responses. The responses were evoked by noxious mechanical stimulation and were recorded as single motor units in male Wistar rats anaesthetized with α‐chloralose.
The effective dose 50 (ED50) observed with fentanyl was 22.4±1.5 μg kg−1 and full recovery was apparent 20 min later. The administration of a total dose of 40 μg kg−1 of dexketoprofen trometamol did not induce any significant effect on the nociceptive responses. In the presence of dexketoprofen trometamol, the ED50 for fentanyl was 5 fold lower than before: 3.8±1.1 μg kg−1 and no significant recovery was observed 45 min later. The opioid antagonist naloxone (200 μg kg−1) did not reverse the effect, although in control experiments the same dose was able to prevent any action of fentanyl given alone.
We conclude that the combination of fentanyl and subeffective doses of dexketoprofen trometamol induces a more potent and longer lasting analgesic effect than that observed with fentanyl alone, and that this is not an opioid mediated action.

British Journal of Pharmacology (2002) 135, 393–398; doi:10.1038/sj.bjp.0704491
Inducing the cell cycle arrest and apoptosis of oral KB carcinoma cells by hydroxychavicol: roles of glutathione and reactive oxygen species
Authors: Chang M C , Uang B J , Wu H L , Lee J J , Hahn L J , Jeng J H 
Published: January 2005

Hydroxychavicol (HC; 10 – 50 μM), a betel leaf component, was found to suppress the 2% H2O2‐induced lucigenin chemiluminescence for 53 – 75%. HC (0.02 – 2 μM) was also able to trap superoxide radicals generated by a xanthine/xanthine oxidase system with 38 – 94% of inhibition. Hydroxyl radicals‐induced PUC18 plasmid DNA breaks was prevented by HC (1.6 – 16 μM).
A 24‐h exposure of KB cells to HC (0.5, 1 mM) resulted in 54 – 74% cell death as analysed by a 3‐(4,5‐dimethyl‐thiazol‐2‐yl)‐2,5‐diphenyl‐tetrazolium bromide (MTT) assay. HC (10, 50 μM) further suppressed the growth of KB cells (15 and 76%, respectively). Long‐term colony formation of KB cells was inhibited by 51% with 10 μM HC.
Pretreatment of KB cells with 100 μM HC inhibited the attachment of KB cells to type I collagen and fibronectin by 59 and 29%, respectively.
Exposure of KB cells to 0.1 mM HC for 24 h resulted in cell cycle arrest at late S and G2/M phase. Increasing the HC concentration to 0.25 and 0.5 mM led to apoptosis as revealed by detection of sub‐G0/G1 peaks with a concomitant decrease in the number of cells residing in late S and G2/M phase.
Inducing the apoptosis of KB cells by HC was accompanied by marked depletion in reduced form of GSH (>0.2 mM) and the increasing of reactive oxygen species production (>0.1 mM) as analysed by CMF‐ and DCF‐single cell fluorescence flow cytometry.
These results indicate that HC exerts antioxidant property at low concentration. HC also inhibits the growth, adhesion and cell cycle progression of KB cells, whereas its induction of KB cell apoptosis (HC>0.1 mM) was accompanied by cellular redox changes.

British Journal of Pharmacology (2002) 135, 619–630; doi:10.1038/sj.bjp.0704492
Andrographolide prevents oxygen radical production by human neutrophils: possible mechanism(s) involved in its anti‐inflammatory effect
Authors: Shen Yuh‐Chiang , Chen Chieh‐Fu , Chiou Wen‐Fei 
Published: January 2005

We have reported that andrographolide (ANDRO), an active component of Andrographis paniculata, inhibits inflammatory responses by rat neutrophils. To further elucidate the possible mechanism(s) underlying the ANDRO's effect, N‐formyl‐methionyl‐leucyl‐phenylalanine (fMLP)‐induced adhesion and transmigration of isolated peripheral human neutrophils were studied.
Pretreatment with ANDRO (0.1–10 μM) concentration‐dependently prevented fMLP‐induced neutrophil adhesion and transmigration. We further examined the up‐expression of surface Mac‐1 (CD11b/CD18), an essential integrin mediated in neutrophil adhesion and transmigration. ANDRO pretreatment significantly decreased fMLP‐induced up‐expression of both CD11b and CD18.
Accumulation of reactive oxygen species (ROS) as well as quick intracellular calcium ([Ca++]i) mobilization induced by fMLP displays two important signalling pathways in regulating the up‐expression of Mac‐1 by neutrophils. That ANDRO pretreatment diminished fMLP‐induced production of H2O2 and O2.−, but failed to block that of [Ca++]i mobilization suggested that the ROS but not [Ca++]i signalling could be modulated by ANDRO.
To clarify whether ROS production impeded by ANDRO could be an antagonism of fMLP binding, phorbol‐12‐myristate‐13‐acetate (PMA), a direct protein kinase C (PKC) activator, was introduced to activate ROS production. PMA triggered remarkable ROS production and adhesion, and were partially reversed by ANDRO. This indicated that a PKC‐dependent mechanism might be interfered by ANDRO.
We conclude that the prevention of ROS production through, at least in part, modulation of PKC‐dependent pathway could confer ANDRO the ability to down‐regulate Mac‐1 up‐expression that is essential for neutrophil adhesion and transmigration.

British Journal of Pharmacology (2002) 135, 399–406; doi:10.1038/sj.bjp.0704493
Pharmacological and functional characterization of the guinea‐pig B2 bradykinin receptor stably expressed in CHO‐K1 cell line
Authors: Robert C , Pruneau D , Paquet J ‐L 
Published: January 2005

In the present study, pharmacological properties of a bradykinin B2 receptor amplified either from guinea‐pig ileum or lung and homologous to the previously reported sequence except two amino‐acid changes L124→P and N227→Y in the receptor protein were characterized.
Tritiated bradykinin ([3H]‐BK) specifically bound to the cloned guinea‐pig B2 bradykinin receptor stably expressed in Chinese hamster ovary cells (CHO‐K1) with a KD value of 0.29±0.07 nM. In competition experiments, bradykinin (BK) affinity constant value was 0.21±0.05 nM while the two specific kinin B1 ligands, des‐Arg9‐bradykinin (DBK) and des‐Arg9‐Leu8‐bradykinin (DLBK) were unable to compete with [3H]‐BK. As the specific peptide antagonist D‐Arg‐[Hyp3,Thi5,D‐Tic7,Oic8]‐bradykinin (HOE140), (E)‐3‐(6‐acetamido‐3‐pyridil)‐N‐[‐N‐[2,4‐dichloro‐3‐[(2‐methyl‐8‐quinolinyl)oxymethyl]phenyl]‐N‐methylaminocarbonylmethyl]acrylamide (FR173657) and 1‐[[3‐[2,4‐dimethylquinolin‐8‐yl)oxymethyl] ‐ 2,4 ‐ dichloro ‐ phenyl]sulfonyl] ‐ 2(S) ‐ [[4‐[4‐(aminoiminomethyl)‐phenylcarbonyl]piperazin‐1‐yl]carbonyl]pyrrolidine (LF16‐0335C) exhibited a high affinity for this receptor with Ki values of 7.34±2.45 nM and 8.54±1.55 nM respectively.
BK and kallidin (KD) increased inositol phosphates (IPs) levels with EC50 values of 0.44±0.12 nM and 6.88±0.28 nM, respectively. Neither DLBK nor DBK (0.01 nM to 10 μM) stimulated or inhibited IPs turnover and as expected HOE140 did not raise IPs production. HOE140 (0.1 μM) and LF 16‐0335c (1 μM) right shifted the BK response curve with pKB values of 9.2±0.4 and 8.4±0.3, respectively.
The results indicate that this cloned guinea‐pig receptor displayed typical pharmacological properties of a bradykinin B2 receptor and support the existence of a single B2 receptor in this species.

British Journal of Pharmacology (2002) 135, 462–468; doi:10.1038/sj.bjp.0704494
The β‐lactam antibiotics, penicillin‐G and cefoselis have different mechanisms and sites of action at GABAA receptors
Authors: Sugimoto Masahiro , Fukami Sakae , Kayakiri Hiroshi , Yamazaki Shunji , Matsuoka Nobuya , Uchida Ichiro , Mashimo Takashi 
Published: January 2005

The action of the β‐lactam antibiotics, penicillin‐G (PCG) and cefoselis (CFSL) on GABAA receptors (GABAA‐R) was investigated using the two‐electrode voltage clamp technique and Xenopus oocyte expressed murine GABAA‐R.
Murine GABAA‐Rs were expressed in Xenopus oocytes by injecting cRNA that encoded for each subunit (α1, β2, and γ2) and the effects of PCG and CFSL on the α1β2γ2s subunit receptors were examined using two‐electrode voltage clamp. Using the α1β2γ2s GABAA‐R, PCG and CFSL inhibited GABA‐induced currents in a concentration‐dependent manner, with IC50s of 557.1±125.4 and 185.0±26.6 μM, respectively. The inhibitory action of PCG on GABA‐induced currents was non‐competitive whereas that of CFSL was competitive.
Mutation of tyrosine to phenylalanine at position 256 in the β2 subunit (β2Y256F), which is reported to abolish the inhibitory effect of picrotoxin, drastically reduced the potency of PCG (IC50=28.4±1.42 mM) for the α1β2Y256Fγ2s receptor without changing the IC50 of CFSL (189±26.6 μM).
These electrophysiological data indicate that PCG and CFSL inhibit GABAA‐R in a different manner, with PCG acting non‐competitively and CFSL competitively. The mutational study indicates that PCG might act on an identical or nearby site to that of picrotoxin in the channel pore of the GABAA‐R.

British Journal of Pharmacology (2001) 135, 427–432; doi:10.1038/sj.bjp.0704496
Interaction of nitric oxide with calcium in the mesenteric bed of bile duct‐ligated rats
Authors: Nadal F Javier A , Atucha Noemí M , Iyu David , García‐Estañ Joaquín 
Published: January 2005

We have analysed the interaction of NO with calcium in order to study the molecular mechanisms responsible for the vascular hyporesponse of liver cirrhosis. The experiments have been performed in the isolated and perfused mesenteric arterial bed of rats with bile duct ligation (BDL) and their controls.
While perfusing the vessels with normal Krebs, methoxamine (MTX) or KCl produced a lower pressor response in the BDL mesenteries. The NO synthesis inhibitor Nw‐nitro‐L‐arginine (NNA) potentiated those responses and abolished the differences between groups.
The administration of MTX under perfusion with zero calcium‐Krebs, to analyse the intracellular release of calcium, also induced a lower response in the BDL mesenteries and NNA potentiated and normalized the response.
To investigate calcium entry, the vessels were perfused with zero‐calcium Krebs containing high potassium to open voltage‐dependent calcium channels. Then, the addition of calcium (10−1–3×10−3 M) produced a lower pressor response in the BDL vessels, that was corrected by NNA. To study calcium entry through receptor‐operated channels, the vessels were perfused with zero‐calcium Krebs containing MTX. The addition of calcium elevated the perfusion pressure less in the BDL mesenteries than in the control and NNA potentiated the responses and eliminated the between groups differences. When calcium entry through both voltage‐ and receptor‐operated channels was simultaneously analysed, similar results were obtained.
In the mesenteric bed of bile duct ligated rats, an excess of nitric oxide affects vascular calcium regulation through an interaction with both calcium entry and intracellular calcium release.

British Journal of Pharmacology (2002) 135, 489–495; doi:10.1038/sj.bjp.0704504
Effects of cardioselective KATP channel antagonism on basal, stimulated, and ischaemic myocardial function in in vivo failing canine heart
Authors: Saavedra Walter F , Paolocci Nazareno , Kass David A 
Published: January 2005

Inhibition of cardiomyocyte‐specific ATP‐sensitive potassium (KATP) channels prolongs the action potential during intense ischaemia with attendant antiarrhythmic effects. However, this is accompanied by contractile depression in some models. These changes may be particularly troublesome in dilated cardiomyopathic hearts that display basal systolic dysfunction, limited energy reserve, and prolonged repolarization favouring arrhythmia. Mechanical effects of selective myocyte KATP channel blockade on basal, β‐adrenergic stimulated, and ischemic responses were therefore tested in dogs with cardiac failure induced by tachypacing.
Cardiovascular function was assessed by pressure – dimension relationships in 10 conscious, chronically instrumented dogs (sonomicrometry/micromanometry), with or without cardiac failure. Cardiomyocyte KATP channels were inhibited by HMR 1098, and data obtained under basal conditions, during epinephrine infusion to raise metabolic demand, during regional ischaemia, and with combined ischaemia+epinephrine.
HMR 1098 had no effect on baseline cardiac function nor did it induce arrhythmia in normal or failing hearts. Epinephrine raised cardiac work 65% and oxygen consumption 55%, yet HMR 1098 had no functional effect in either heart condition. Regional ischaemia with or without epinephrine co‐stimulation depressed regional and global function, yet both were also unaffected by HMR 1098. There was minimal arrhythmia without HMR 1098, and drug infusion did not alter this.
Thus, myocyte‐KATP channels play a negligible role modulating intact in vivo cardiac contraction or arrhythmia in normal and failing heart with and without increased metabolic demand and/or regional ischaemia. This supports the feasibility of administering such agents to depressed hearts, despite underlying contractile and electrophysiologic abnormalities.

British Journal of Pharmacology (2002) 135, 657–662; doi:10.1038/sj.bjp.0704510
Inhibition of adenylyl cyclase by neuronal P2Y receptors
Authors: Unterberger Ursula , Moskvina Eugenia , Scholze Thomas , Freissmuth Michael , Boehm Stefan 
Published: January 2005

P2Y receptors inhibiting adenylyl cyclase have been found in blood platelets, glioma cells, and endothelial cells. In platelets and glioma cells, these receptors were identified as P2Y12. Here, we have used PC12 cells to search for adenylyl cyclase inhibiting P2Y receptors in a neuronal cellular environment.
ADP and ATP (0.1 – 100 μM) left basal cyclic AMP accumulation unaltered, but reduced cyclic AMP synthesis stimulated by activation of endogenous A2A or recombinant β2 receptors. Forskolin‐dependent cyclic AMP production was reduced by 1 μM and enhanced by 10 – 100 μM ADP; this latter effect was turned into an inhibition when A2A receptors were blocked.
The nucleotide inhibition of cyclic AMP synthesis was not altered when P2X receptors were blocked, but abolished by pertussis toxin.
The rank order of agonist potencies for the reduction of cyclic AMP was (IC50 values): 2‐methylthio‐ADP (0.12 nM)=2‐methylthio‐ATP (0.13 nM)>ADPβS (71 nM)>ATP (164 nM)=ADP (244 nM). The inhibition by ADP was not antagonized by suramin, pyridoxal‐phosphate‐6‐azophenyl‐2′,4′‐disulphonic acid, or adenosine‐3′‐phosphate‐5′‐phosphate, but attenuated by reactive blue 2, ATPαS, and 2‐methylthio‐AMP.
RT – PCR demonstrated the expression of P2Y2, P2Y4, P2Y6, and P2Y12, but not P2Y1, receptors in PC12 cells. In Northern blots, only P2Y2 and P2Y12 were detectable. Differentiation with NGF did not alter these hybridization signals and left the nucleotide inhibition of adenylyl cyclase unchanged.
We conclude that P2Y12 receptors are expressed in neuronal cells and inhibit adenylyl cyclase activity.

British Journal of Pharmacology (2002) 135, 673–684; doi:10.1038/sj.bjp.0704514
Nociceptin/orphanin FQ inhibits capsaicin‐induced guinea‐pig airway contraction through an inward‐rectifier potassium channel
Authors: Jia Yanlin , Wang Xin , Aponte Sonia I , Rivelli Maria A , Yang Richard , Rizzo Charles A , Corboz Michel R , Priestley Tony , Hey John A 
Published: January 2005

Nociceptin/orphanin FQ (N/OFQ), an endogenous opioid‐like orphan receptor (NOP receptor, previously termed ORL1 receptor) agonist, has been found to inhibit capsaicin‐induced bronchoconstriction in isolated guinea‐pig lungs and in vivo. The underlying mechanisms are not clear. In the present studies, we tested the effect of N/OFQ on VR1 channel function in isolated guinea‐pig nodose ganglia cells. Capsaicin increased intracellular Ca2+ concentration in these cells through activation of vanilloid receptors. Capsaicin‐induced Ca2+ responses were attenuated by pretreatment of nodose neurons with N/OFQ (1 μM).
N/OFQ inhibitory effect on the Ca2+ response in nodose ganglia cells was antagonized by tertiapin (0.5 μM), an inhibitor of inward‐rectifier K+ channels, but not by verapamil, a voltage gated Ca2+ channel blocker, indicating that an inward‐rectifier K+ channel is involved in N/OFQ inhibitory effect.
In isolated guinea‐pig bronchus, N/OFQ (1 μM) inhibited capsaicin‐induced airway contraction. Tertiapin (0.5 μM) abolished the N/OFQ inhibition of capsaicin‐induced bronchial contraction.
Capsaicin (10 μg) increased pulmonary inflation pressure in the isolated perfused guinea‐pig lungs. This response was significantly attenuated by pretreatment with N/OFQ (1 μM). Tertiapin also abolished the N/OFQ inhibitory effect on capsaicin‐induced bronchoconstriction in perfused lungs. Capsaicin increased the release of substance P and neurokinin A from isolated lungs. N/OFQ (1 μM) blocked the capsaicin‐induced tachykinin release.
These results indicate that N/OFQ‐induced hyperpolarization of tachykinin containing airway sensory nerves, through an inward‐rectifier K+ channel activation, accounts for the inhibition of capsaicin‐evoked broncoconstriction.

British Journal of Pharmacology (2002) 135, 764–770; doi:10.1038/sj.bjp.0704515
Aconitine facilitates spontaneous transmitter release at rat ventromedial hypothalamic neurons
Authors: Yamanaka Hisashi , Doi Atsushi , Ishibashi Hitoshi , Akaike Norio 
Published: January 2005

The effects of aconitine, an Aconitum alkaloid, on spontaneous inhibitory and excitatory postsynaptic currents (IPSCs and EPSCs respectively) were investigated in the mechanically dissociated rat ventromedial hypothalamic (VMH) neurons in which native presynaptic nerve terminals remained intact.
Under current‐clamp conditions, aconitine (3×10−6 M) depolarized the neuron with generating the action potentials. The aconitine‐induced depolarization was markedly suppressed in the presence of CNQX but it was facilitated in the presence of bicuculline, suggesting that release of excitatory and inhibitory neurotransmitters may be involved in the aconitine action in addition to its direct action on postsynaptic membrane.
Under the voltage‐clamp conditions, aconitine reversibly increased the frequency of spontaneous IPSC and EPSC frequency, but it did not alter their amplitude distribution.
Tetrodotoxin (TTX, 3×10−7 M) completely abolished the aconitine action on spontaneous IPSC frequency. Likewise removal of extracellular Na+ completely suppressed the aconitine action.
Both Ca2+‐free external solution or addition of 10−4 M Cd2+ to normal solutions eliminated the facilitatory effect of aconitine on the IPSC frequency.
Overall these results suggest that aconitine depolarizes the presynaptic membrane by activating voltage‐dependent Na+ channels. Increase of intraterminal Ca2+ concentration via an activation of voltage‐dependent Ca2+ channels in turn enhances the spontaneous transmitter release from presynaptic nerve terminals. The presynaptic action of aconitine may play a crucial role for membrane excitability of rat VMH neurons.

British Journal of Pharmacology (2002) 135, 816–822; doi:10.1038/sj.bjp.0704517
Pharmacological characterization of a non‐inactivating outward current observed in mouse cerebellar Purkinje neurones
Authors: Bushell Trevor , Clarke Catherine , Mathie Alistair , Robertson Brian 
Published: January 2005

Whole‐cell patch clamp recordings were used to investigate the properties of a non‐inactivating outward current observed in mouse cerebellar Purkinje neurones at a holding potential of −20 mV.
Increasing the external potassium (K+) concentration from 3 mM to 20 mM produced a rightward shift in the observed reversal potential of ∼30 mV or ∼40 mV for a K+‐or a caesium (Cs+)‐based intracellular solution respectively, indicating the outward current was a K+ current.
The outward current was partially inhibited by the K+ channel blocker, tetraethylammonium (TEA; IC50=0.15 mM). Subsequently, the background or TEA‐insensitive current was measured in the presence of 1 mM TEA.
The background current was reversibly inhibited by barium (Ba2+; 300 μM, 50%) and potentiated by the application of arachidonic acid (AA; 1 mM, 62%).
The volatile anaesthetic, halothane (1 mM), and the neuroprotectant, riluzole (500 μM), both reversibly inhibited the background current by 54% and 36% respectively.
The background current was insensitive to changes in both intracellular and extracellular acidification.
The GABAB and μ‐opioid receptor agonists, baclofen and [D‐Ala2, N‐MePhe4‐Gly‐ol5] enkephalin (DAMGO) both reversibly potentiated the outward current by 42% and 26% respectively. In contrast, the metabotropic glutamate receptor and acetylcholine receptor agonists, (S)‐3,5‐dihydroxyphenylglycine (DHPG) and muscarine both reversibly inhibited the outward current by 48% and 42% respectively.
These data suggest that cerebellar Purkinje neurones possess a background current which shares several properties with recently cloned two‐pore K+ channels, particularly THIK‐1.

British Journal of Pharmacology (2002) 135, 705–712; doi:10.1038/sj.bjp.0704518