bluuebunny/crossref_metadata_2025_split huggingface dataset:
Anti‐spasmogenic activity of isoenzyme‐selective phosphodiesterase inhibitors in guinea‐pig trachealis
Authors: Bernareggi Micaela M , Belvisi Maria G , Patel Hema , Barnes Peter J , Giembycz Mark A 
Published: January 2005

The anti‐spasmogenic potential of SK&F 94120 (PDE3‐selective), rolipram (PDE4‐selective), zaprinast (PDE5‐selective), zardaverine (dual PDE3/4 inhibitor) and theophylline (non‐selective) was evaluated in guinea‐pig trachealis.
SK&F 94120 or rolipram (10 and 100 μM) antagonized histamine‐induced tension generation in a concentration‐dependent and non‐competitive manner whereas ACh‐induced contractions were unaffected. Similarly, SK&F 94120 and rolipram in combination were anti‐spasmogenic with respect to both contractile agonists to an extent that was greater than the effect of either drug alone. Identical results were obtained with zardaverine (1, 10 and 100 μM) and theophylline (100 μM and 1 mM).
Zaprinast protected guinea‐pig trachealis against histamine‐, but not ACh‐induced contractile responses in a manner that was indistinguishable from the results obtained with SK&F 94120. However, in contrast to the interaction between SK&F 94120 and rolipram, no further antagonism was seen when zaprinast and rolipram were used in combination.
Pre‐treatment of tissues with SNP (10 and 100 μM) antagonized histamine‐induced tension generation in a concentration‐dependent and non‐competitive manner. However, no further antagonism was produced when SNP and rolipram were used concurrently. Likewise, the protection afforded by a combination SNP and SK&F 94120 was no greater than that produced by SNP alone.
These results demonstrate that an inhibitor of PDE3 enhances the anti‐spasmogenic activity of rolipram but not drugs that elevate cyclic GMP mass. Moreover, the ability of SNP and zaprinast to protect guinea‐pig trachealis against histamine‐induced contractions apparently is not due to the inhibition of PDE3.

British Journal of Pharmacology (1999) 128, 327–336; doi:10.1038/sj.bjp.0702779
Characterization of recombinant human orexin receptor pharmacology in a Chinese hamster ovary cell‐line using FLIPR
Authors: Smart D , Jerman J C , Brough S J , Rushton S L , Murdock P R , Jewitt F , Elshourbagy N A , Ellis C E , Middlemiss D N , Brown F 
Published: January 2005

The cellular mechanisms underlying the physiological effects of the orexins are poorly understood. Therefore, the pharmacology of the recombinant human orexin receptors was studied using FLIPR. Intracellular calcium ([Ca2+]i) was monitored in Chinese hamster ovary (CHO) cells stably expressing orexin‐1 (OX1) or orexin‐2 (OX2) receptors using Fluo‐3AM. Orexin‐A and orexin‐B increased [Ca2+]i in a concentration dependent manner in CHO‐OX1 (pEC50=8.03±0.08 and 7.30±0.08 respectively, n=5) and CHO‐OX2 (pEC50=8.18±0.10 and 8.43±0.09 respectively, n=5) cells. This response was typified as a rapid peak in [Ca2+]i (maximal at 6–8 s), followed by a gradually declining secondary phase. Thapsigargin (3 μM) or U73122 (3 μM) abolished the response. In calcium‐free conditions the peak response was unaffected but the secondary phase was shortened, returning to basal values within 90 s. Calcium (1.5 mM) replacement restored the secondary phase. In conclusion, orexins cause a phospholipase C‐mediated release of calcium from intracellular stores, with subsequent calcium influx.British Journal of Pharmacology (1999) 128, 1–3; doi:10.1038/sj.bjp.0702780
Iodinated radiographic contrast media inhibit shear stress‐ and agonist‐evoked release of NO by the endothelium
Authors: Hutcheson I R , Griffith T M , Pitman M R , Towart R , Gregersen M , Refsum Helge , Karlsson J O G 
Published: January 2005

We have used isolated arterial preparations from the rabbit and dog to investigate whether non‐ionic iodinated radiographic contrast media (IRCM) modulate nitric oxide (NO) release. The tri‐iodinated monomers iopromide and iohexol were compared with the hexa‐iodinated dimer iodixanol.
The vasodilator effects of iohexol (300 mg ml−1) and iodixanol (320 mg ml−1) were assessed in cascade bioassay. Increasing concentrations of iohexol or iodixanol caused concentration‐dependent relaxations of the detector tissue which were insensitive to 100 μM NG‐nitro L‐arginine methyl ester (L‐NAME) and 10 μM indomethacin, whereas viscosity‐associated relaxations induced by the ‘inert’ agent dextran (MW 80,000; 1–4%) were attenuated by inhibition of NO synthesis.
Relaxations of endothelium‐intact rings to acetylcholine (ACh) were attenuated by preincubation with iohexol or iodixanol, whereas relaxations to sodium nitroprusside (SNP) in endothelium‐denuded rings were unaffected. Inhibitory activity did not correlate with either molarity or iodine concentration. Mannitol caused inhibition of both ACh‐ and SNP‐induced responses.
In isolated perfused arteries the depressor responses to iodixanol (320 mg ml−1) and iopromide (300 mg ml−1) administered as close arterial bolus attained a plateau with maximal dilatations of ∼25% and ∼60%, respectively. Addition of 100 μM NG‐nitro L‐arginine (L‐NOARG) and/or 10 μM indomethacin to the perfusate had no effect on the responses to either agent.
We conclude that IRCM exert direct effects on the endothelium that inhibit NO production rather than its action on vascular smooth muscle. Shear stress‐induced stimulation of NO production by IRCM is unlikely to contribute to their vasodilator activity in vivo when administered during angiography despite high intrinsic viscosity.

British Journal of Pharmacology (1999) 128, 451–457; doi:10.1038/sj.bjp.0702781
Cyclosporin A and tacrolimus (FK506) suppress expression of inducible nitric oxide synthase in vitro by different mechanisms
Authors: Dusting Gregory J , Akita Kazuhiro , Hickey Haruyo , Smith Melanie , Gurevich Vladimir 
Published: January 2005

The effects of the immunosuppressant drugs cyclosporin A and tacrolimus (FK506) on nitric oxide synthesis were examined in a murine macrophage cell line (J774) and rat vascular smooth muscle cells (VSMC) in culture for 24 and 48 h, respectively.
Cyclosporin A (0.01–10 μM) inhibited by up to 90% accumulation of nitrite induced by lipopolysaccharide (LPS) in both cell lines, but FK506 (0.01–10 μM) had a weaker effect on nitrite accumulation in these cells. Cyclosporin A and FK506 (at 1 μM) also significantly inhibited nitrite production induced by recombinant murine interferon‐γ (rIFNγ) and recombinant murine interleukin‐1β (rIL‐1β) in J774 and VSMC, respectively.
In J774 cells, cyclosporin A (but not FK506) at 1 μM was inhibitory when co‐incubated with the inducing agents but not when the cells were treated with the immunosuppressant before or after the inducer. In VSMC, nitrite production was inhibited by co‐incubation of cyclosporin A or FK506 with the inducer, or when the immunosuppressants were pre‐incubated with cells. In contrast, N‐monomethyl L‐arginine (NMMA) abolished nitrite production when incubated with either cell type during or after addition of inducing agent, but not if cells were preincubated with NMMA.
RNA extracted from treated J774 and VSMC was subjected to reverse transcription–polymerase chain reaction (RT–PCR). Cyclosporin A, but not FK506, suppressed expression of mRNA for NOS2 in a concentration‐dependent manner when co‐incubated with LPS.
The fact that the potency difference between cyclosporin A and FK506 for NO suppression is the opposite to that for inhibition of interleukin‐2 generation suggests that the immunosuppressants act in J774 macrophages and VSMC through intracellular mechanisms that differ from those elucidated in T‐cells. Cyclosporin A suppresses NOS2 gene transcription, but FK506 acts post‐transcriptionally to suppress NO generation in VSMC.
Taken together the present data suggest that therapeutic concentrations of cyclosporin A, but not FK506, might well suppress NO production, but FK506 would not have this effect. Suppression of NO might contribute to the side effects of hypertension and nephrotoxicity associated with long‐term use of cyclosporin A to prevent transplant rejection.

British Journal of Pharmacology (1999) 128, 337–344; doi:10.1038/sj.bjp.0702782
Stimulation of bradykinin B2‐receptors on endothelial cells induces relaxation and contraction in porcine basilar artery in vitro
Authors: Miyamoto Atsushi , Ishiguro Shigeru , Nishio Akira 
Published: January 2005

The aim of the present study was to characterize the subtypes of bradykinin (BK) receptors that evoke the relaxation and contraction induced by BK and to identify the main contracting and relaxing factors in isolated porcine basilar artery by measuring changes in isometric tension and a thromboxane (TX) metabolite.
Endothelial denudation completely abolished both responses. [Thi5,8, D‐Phe7]‐BK (a B2‐receptor antagonist) inhibited the BK‐induced relaxation and contraction, whereas des‐Arg9, [Leu8]‐BK (a B1‐receptor antagonist) had no effect.
L‐nitro‐arginine (L‐NA, a nitric oxide synthase inhibitor) completely inhibited BK‐induced relaxation. Indomethacin (a cyclo‐oxygenase inhibitor) completely and ONO‐3708 (a TXA2/prostaglandin H2 receptor antagonist) partially inhibited BK‐induced contraction, whereas OKY‐046 (a TXA2 synthase inhibitor) and nordihydroguaiaretic acid (a lipoxygenase inhibitor) did not.
In the presence of L‐NA, the contractile response to BK was inhibited by indomethacin or ONO‐3708 and was competitively antagonized by [Thi5,8, D‐Phe7]‐BK (pA2=7.50). In the presence of indomethacin, the relaxant response to BK was inhibited by L‐NA and was competitively antagonized by [Thi5,8, D‐Phe7]‐BK (pA2=7.59).
TXA2 release was not induced by BK‐stimulation.
These results suggest that the endothelium‐dependent relaxation and contraction to BK in the porcine basilar artery is mediated via activation of endothelial B2‐receptors. The main relaxing factor may be NO and the main contracting factor may be prostaglandin H2.

British Journal of Pharmacology (1999) 128, 241–247; doi:10.1038/sj.bjp.0702783
Characterization of non‐adrenergic, non‐cholinergic inhibitory responses of the isolated guinea‐pig trachea: differences between pre‐ and post‐ganglionic nerve stimulation
Authors: Moffatt James D , Dumsday Bryan , McLean John R 
Published: January 2005

Differences in the mechanism of non‐adrenergic, non‐cholinergic (NANC) inhibitory responses to preganglionic‐ and post‐ganglionic nerve stimulation were investigated in the guinea‐pig isolated trachea.
Stimulation of the vagus nerve at frequencies above 4 Hz elicited NANC relaxation of the trachealis muscle. Responses to low frequencies of stimulation (4–8 Hz) were abolished by the nitric oxide (NO) synthase inhibitor L‐NOARG (10 μM), while a L‐NOARG resistant component was observed at higher stimulus frequencies. The L‐NOARG‐resistant component of NANC inhibitory responses to higher frequencies of vagus nerve stimulation were significantly attenuated by the proteinase α‐chymotrypsin (2 U/ml), suggesting that a neuropeptide such as VIP may contribute to NANC responses.
When postganglionic nerves were stimulated by electrical field stimulation (EFS), responses were readily elicited at frequencies below 4 Hz. Like responses to vagus nerve stimulation, responses to low frequency (<4 Hz) EFS were abolished by L‐NOARG while a L‐NOARG‐resistant component was apparent at higher stimulus frequencies.
The L‐NOARG‐resistant component of NANC inhibitory responses to EFS was sensitive to α‐chymotrypsin only if stimuli were delivered in either long trains at a low frequency (4 Hz for 10–30 s) or short trains of high frequency (16 Hz for 2.5–7.5 s).
Responses to preganglionic nerve stimulation were approximately 35% of the amplitude of responses to EFS in the same preparations.
In conclusion, responses to preganglionic and postganglionic NANC inhibitory nerve stimulation in the guinea‐pig trachea differ in maximum amplitude, frequency‐response characteristics and the contributions of cotransmitters. We suggest that these differences may be explained by filtering of preganglionic input to postganglionic NANC neurons. These results have implications in all studies where EFS is considered to be representative of physiological stimulation of post‐ganglionic nerve stimulation.

British Journal of Pharmacology (1999) 128, 458–464; doi:10.1038/sj.bjp.0702786
Rat chromaffin cells lack P2X receptors while those of the guinea‐pig express a P2X receptor with novel pharmacology
Authors: Liu M , Dunn P M , King B F , Burnstock G 
Published: January 2005

Whole‐cell patch‐clamp recording was used to determine the functional expression and pharmacological properties of P2X receptors in chromaffin cells dissociated from adrenal medullae of rats and guinea‐pigs.
In rat chromaffin cells maintained in culture for 1–7 days, ATP and UTP failed to evoke any detectable response.
Guinea‐pig chromaffin cells responded to ATP (100 μM) with a rapidly activating inward current. The amplitude of the response to ATP increased over the period cells were maintained in culture and so did the number of cells giving a detectable response, with 69% of cells responding after 4 days of culture.
The response to ATP desensitized slowly, and had a reversal potential of 2.5 mV. The EC50 for ATP was 43 μM. The potency order for ATP analogues was 2‐MeSATP>ATP>ADP. Adenosine, UTP and α,β‐meATP were inactive.
Suramin (100 μM) and Cibacron blue (50 μM) inhibited the ATP (100 μM)‐activated current by 51 and 47%, respectively. PPADS antagonized the response to ATP (100 μM) with an IC50 of 3.2 μM.
The ATP concentration‐response curve shifted to the left at pH 6.8 (EC50, 19 μM) and right at pH 8.0 (EC50, 96 μM), without changing the maximal response. Zn2+ inhibited the response to ATP (100 μM) with an IC50 of 48 μM.
This study indicates that expression of ATP‐gated cation channels in chromaffin cells is species dependent. The P2X receptors in guinea‐pig chromaffin cells show many characteristics of the P2X2 receptor subtype.

British Journal of Pharmacology (1999) 128, 61–68; doi:10.1038/sj.bjp.0702790
Multiple calcium channels regulate neurotransmitter release from vagus nerve terminals in the cat bronchiole
Authors: Fujisawa Kanichiro , Onoue Hitoshi , Abe Kihachiro , Ito Yushi 
Published: January 2005

Twitch‐like contractions and non‐adrenergic non‐cholinergic (NANC) relaxations evoked by electrical field stimulation (EFS) of the cat bronchiole were used to examine the voltage‐activated calcium channels involved in excitatory and inhibitory neurotransmission in the cat bronchiole.
Nifedipine (50 μM), the L‐type calcium channel antagonist, did not affect the twitch‐like contraction and NANC relaxations. However, low concentrations of the N‐type calcium channel blocker ω‐conotoxin GVIA (ω‐CgTX GVIA) (0.1 μM) irreversibly abolished twitch‐like contractions evoked by trains of EFS 10 stimuli at 20 Hz.
After the prolonged treatment with 0.1 μM ω‐CgTX GVIA, EFS evoked initial fast and later slow NANC relaxations in the presence of 5‐HT (10 μM), atropine and guanethidine (1 μM each). However increased concentration of ω‐CgTX GVIA (1 μM) completely suppressed the slow NANC relaxation without affecting the initial fast component.
ω‐agatoxin IVA (100 nM), the P‐ and Q‐type calcium channel inhibitor, and nimodipine (10 μM), the L‐ and T‐type calcium channel blocker, did not affect the amplitude of the initial fast NANC relaxation in the absence or presence of ω‐CgTX GVIA (1 μM).
The contraction or relaxation induced by exogenous acetylcholine (ACh) (0.5 μM) or the nitric oxide donor, s‐nitroso‐N‐acetyl penicillamine (SNAP) (1 μM) were not affected by ω‐CgTX GVIA (1 μM).
Taken together, these results suggest that generation of twitch‐like contraction and later slow NANC relaxation are regulated by N‐type calcium channels, whereas generation of the initial fast NANC relaxation possibly involves R‐type calcium channel.

British Journal of Pharmacology (1999) 128, 262–268; doi:10.1038/sj.bjp.0702791
Modulatory activity of extracellular H+ and Zn2+ on ATP‐responses at rP2X1 and rP2X3 receptors
Authors: Wildman S S , King B F , Burnstock G 
Published: January 2005

The modulatory activity of extracellular H+ and Zn2+ was examined on ATP‐responses at rat P2X1 (rP2X1) and rat P2X3 (rP2X3) receptors expressed in Xenopus oocytes and studied under voltage‐clamp conditions.
Superfused ATP (0.03–30 μM, at pH 7.5) evoked inward currents at rP2X1 receptors (EC50 value, 300±7 nM). ATP potency was reduced 2 fold at pH 6.5, and 6 fold at pH 5.5, without altering the maximum ATP effect. Alkaline conditions (pH 8.0) did not alter ATP activity.
Superfused ATP (0.01–300 μM, at pH 7.5) evoked inward currents at rP2X3 receptors (EC50 value, 1.8±0.3 μM). ATP activity was affected only at pH 5.5, reducing agonist potency 15 fold without altering the maximum ATP effect.
Extracellular Zn2+ inhibited ATP‐responses at rP2X1 receptors in a time‐dependent manner, a 20 min pre‐incubation being optimal (IC50 value, 1.0±0.2 μM). However, the Zn2+ effect was pH‐independent, suggesting Zn2+‐ and H+‐inhibition of ATP‐responses occur through independent processes.
Extracellular Zn2+ weakly potentiated ATP‐responses at rP2X3 receptors (EC50 value, 11±1 μM). The Zn2+ effect was dependent on pre‐incubation time and, with 20 min pre‐incubation periods, Zn2+ potentiated then inhibited ATP‐responses in a concentration‐dependent, but pH‐independent, manner.
In summary, ATP activity at rP2X1 receptors was decreased by both extracellular H+ and Zn2+ and their effects were additive. ATP activity at rP2X3 receptors was less sensitive to H+‐inhibition and, in contrast, was potentiated by Zn2+ in a pH‐independent manner. These differential effects may help distinguish P2X1 and P2X3 receptors in whole tissues.

British Journal of Pharmacology (1999) 128, 486–492; doi:10.1038/sj.bjp.0702802
Monophosphoryl lipid A provides biphasic cardioprotection against ischaemia‐reperfusion injury in rat hearts
Authors: Yamashita Nobushige , Hoshida Shiro , Otsu Kinya , Taniguchi Naoyuki , Kuzuya Tsunehiko , Hori Masatsugu 
Published: January 2005

We utilized a rat model of myocardial infarction to investigate whether cardioprotection by monophosphoryl lipid A (MLA) is provided in the early and late phases, as well as to determine whether this cardioprotection may be related to the activation of manganese superoxide dismutase (Mn‐SOD), an intrinsic radical scavenger.
Pretreatment with MLA (0.5 or 1.0 mg kg−1, i.v.) 24 h prior to 20‐min left coronary artery (LCA) occlusion and 48‐h reperfusion significantly decreased the incidence of ventricular fibrillation (VF) during ischaemia, as well as infarct size. Pretreatment with lower concentrations of MLA, however, was ineffective.
When we examined the time course of MLA (0.5 mg kg−1)‐induced cardioprotection, both infarct size and the incidence of VF were significantly reduced in rats pretreated with MLA 0.5 h and 24 h before occlusion. We observed no differences, however, 2 and 72 h after MLA treatment.
The activity of Mn‐SOD paralleled the cardioprotective effects of MLA. Mn‐SOD activity in the myocardium was significantly enhanced in rats pretreated with MLA (0.5 mg kg−1) 0.5 and 24 h before. Mn‐SOD activity was not altered, however, in rats pretreated 2 or 72 h before. Lower MLA concentrations were not effective even 24 h after the treatment.
We conclude that MLA treatment induced a biphasic pattern of cardioprotection. The pattern of Mn‐SOD activity suggests that this enzyme may play a major role in the acquisition of cardioprotection against ischaemia‐reperfusion injury.

British Journal of Pharmacology (1999) 128, 412–418; doi:10.1038/sj.bjp.0702809
Resiniferatoxin‐type phorboid vanilloids display capsaicin‐like selectivity at native vanilloid receptors on rat DRG neurons and at the cloned vanilloid receptor VR1
Authors: Szallasi A , Szabó T , Bíró T , Modarres S , Blumberg P M , Krause J E , Cortright D N , Appendino G 
Published: January 2005

Although the cloned rat vanilloid receptor VR1 appears to account for both receptor binding and calcium uptake, the identification of vanilloids selective for one or the other response is of importance because these ligands may induce distinct patterns of biological activities.
Phorbol 12,13‐didecanoate 20‐homovanillate (PDDHV) evoked 45Ca2+‐uptake by rat dorsal root ganglion neurons (expressing native vanilloid receptors) in culture with an EC50 of 70 nM but inhibited [3H]‐resiniferatoxin (RTX) binding to rat dorsal root ganglion membranes with a much lower potency (Ki>10,000 nM). This difference in potencies represents a more than 100 fold selectivity for capsaicin‐type pharmacology.
45Ca2+ influx by PDDHV was fully inhibited by the competitive vanilloid receptor antagonist capsazepine, consistent with the calcium uptake occurring via vanilloid receptors.
PDDHV induced calcium mobilization in CHO cells transfected with the cloned rat vanilloid receptor VR1 with an EC50 of 125 nM and inhibited [3H]‐RTX binding to these cells with an estimated Ki of 10,000 nM. By contrast, PDDHV failed to evoke a measurable calcium response in non‐transfected CHO cells, confirming its action through VR1.
We conclude that PDDHV is two orders of magnitude more potent for inducing calcium uptake than for inhibiting RTX binding at vanilloid receptors, making this novel vanilloid a ligand selective for capsaicin‐type pharmacology. These results emphasize the importance of monitoring multiple endpoints for evaluation of vanilloid receptor structure‐activity relations. Furthermore, PDDHV now provides a tool to explore the biological correlates of capsaicin‐type vanilloid pharmacology.

British Journal of Pharmacology (1999) 128, 428–434; doi:10.1038/sj.bjp.0702810
Influence of nitrovasodilators and endothelin‐1 on rheology of human blood in vitro
Authors: Walter Roland , Mark Michael , Gaudenz Roman , Harris Llinos G , Reinhart Walter H 
Published: January 2005

The shear stress of flowing blood profoundly influences the release of endothelium‐dependent vasodilative and constrictive factors. Conversely, the influence of these mediators such as nitric oxide (NO) or endothelin‐1 (ET‐1) on blood rheology remains elusive. In the present study the influence of nitrovasodilators and ET‐1 on red blood cell (RBC) shape and whole blood viscosity were investigated.
Incubation of whole blood with sodium‐nitroprusside (SNP, 10−5–10−2 M), glyceryl trinitrate (GTN, 0.0001–0.1 mg mL−1), S‐nitroso‐N‐acetylpenicillamine (SNAP, 10−6–10−3 M), and the active metabolite of molsidomine (SIN‐1, 10−6–10−3 M), but not molsidomine (10−6–10−3 M), resulted in significantly increased amounts of methaemoglobin, indicating a relevant interaction with RBCs. Treatment with SNP at 10−2 M induced a marked echinocytosis (morphological index: 2.23±0.98 vs −0.17±0.10; P<0.001) and increased blood viscosity (haematocrit 45%) at a high shear rate of 94.5 s−1 (6.46±0.60 vs 5.07±0.35 mPa·s; P<0.01) and a low shear rate of 0.1 s−1 (88.6±36.8 vs 42.1±11.7 mPa·s; P<0.01). Echinocytosis was probably due to cyanide accumulation. SIN‐1 at 10−3 M slightly decreased high shear viscosity (4.88±0.28 vs 4.95±0.30 mPa·s; P<0.05). SNAP at 10−3 M slightly increased both high (5.14±0.23 vs 5.05±0.24 mPa·s; P<0.01) and low shear (53.9±7.2 vs 51.2±5.9 mPa·s; P<0.05) viscosity. Molsidomine and GTN failed to influence whole blood viscosity. ET‐1 (10−9–10−6 M) had no effect on RBC shape and viscosity.
We conclude that the most important modulators of vascular tone, NO and ET‐1, do not affect RBC shape and blood viscosity, which is important from both a physiological and a pharmacological point of view.

British Journal of Pharmacology (1999) 128, 744–750; doi:10.1038/sj.bjp.0702817