bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evidence that [3H]‐α,β‐methylene ATP may label an endothelial‐derived cell line 5′‐nucleotidase with high affinity
Authors: Michel A.D. , Chau N.‐M. , Fan T.‐P.D. , Frost E.E. , Humphrey P.P.A. 
Published: July 2012

In membranes prepared from a permanent cell line of endothelial origin (WEC cells), [3H]‐α,β‐methylene ATP ([3H]‐α,β‐meATP) labelled high (pKd = 9.5; Bmax = 3.75 pmol mg−1 protein) and low (pKd = 7.2; Bmax = 23.3 pmol mg−1 protein) affinity binding sites. The high affinity [3H]‐α,β‐meATP binding sites in the WEC cell membranes could be selectively labelled with a low concentration of the radioligand (1 nM). In competition studies performed at a radioligand concentration of 1 nM, 88.6% of the sites possessed high affinity (pIC50 = 8.26) for α,β‐meATP.
The high affinity [3H]‐α,β‐meATP binding sites appeared heterogeneous since in competition studies a number of nucleotide analogues (α,β‐meADP, ATP, ADP, AMP, GTP, GppNHp, GMP) and adenosine identified two populations of the sites labelled by 1 nM [3H]‐α,β‐meATP. The proportion of sites with high affinity for these compounds was found to vary between 42 and 69°.
Approximately 60–69% of the binding sites labelled with 1 nM [3H]‐α,β‐meATP possessed high affinity for α,β‐meADP (pIC50 = 8.87), AMP (pIC50 = 7.12), GMP (pIC50 = 7.34), UTP (pIC50 = 6.12), GTP (pIC50 = 7.59), GppNHp (plC50 = 735) and adenosine (pIC50 = 5.45). The sites at which these compounds possessed high affinity were probably the same, since, in the presence of GMP at a concentration (10 μm) sufficient to inhibit selectively the binding of [3H]‐α,β‐meATP, the [3H]‐α,β‐meATP binding sites with high affinity for AMP, UTP, α,β‐meADP, GTP, GppNHp and adenosine were also occluded.
WEC cell membranes were able to metabolize a trace concentration (6 nM) of [3H]‐AMP to [3H]‐adenosine under the conditions of the binding assay. The pIC50 values of adenosine (5.99), GMP (7.55) and the substrate AMP (7.19) for inhibiting this [3H]‐AMPase activity were almost identical to their high affinity pIC50 estimates obtained in the binding assay. Although α,β‐meADP, α,β‐meATP, β,γ‐meATP, ATP, ADP and GppNHp identified heterogeneity in the [3H]‐AMPase activity of the WEC cells, their pIC50 values for inhibiting the major portion of the [3H]‐AMPase activity were similar to their respective high affinity pIC50 values in the binding assay. It thus seems likely that WEC cells express a form of 5′‐nucleotidase that possesses high affinity for both α,β‐meADP and α,β‐meATP and that this enzyme can be labelled by [3H]‐α,β‐meATP.
In the presence of 10 μm GMP, the affinity estimates for α,β‐meADP, AMP, GMP, GTP, GppNHp, ADP and adenosine at the high affinity [3H]‐α,β‐meATP binding sites that remained available, were low and similar to their affinity estimates at the high affinity [3H]‐α,β‐meATP binding sites of rat vas deferens. Since the high affinity [3H]‐α,β‐meATP binding sites in rat vas deferens are thought to be P2x purinoceptors it is possible that the high affinity [3H]‐α,β‐meATP binding sites in the WEC which possess low affinity for α,β‐meADP are also P2x purinoceptors.
Noradrenaline contractions of human prostate mediated by α1c‐(α1c‐) adrenoceptor subtype
Authors: Marshall Ian , Burt Richard P. , Chappie Christopher R. 
Published: July 2012

The subtype of α1‐adrenoceptor mediating contractions of human prostate to noradrenaline was characterized by use of a range of competitive and non‐competitive antagonists.
Contractions of the prostate to either noradrenaline (pD2 5.5), phenylephrine (pD2 5.1) or methoxamine (pD2 4.4) were unaltered by the presence of neuronal and extraneuronal uptake blockers. Noradrenaline was about 3 and 10 times more potent than phenylephrine and methoxamine respectively. Phenylephrine and methoxamine were partial agonists.
Pretreatment with the alkylating agent, chlorethylclonidine (10−4 m) shifted the noradrenaline concentration‐contraction curve about 3 fold to the right and depressed the maximum response by 31%. This shift is 100 fold less than that previously shown to be produced by chlorethylclonidine under the same conditions on α1B‐adrenoceptor‐mediated contractions.
Cumulative concentration‐contraction curves for noradrenaline were competitively antagonized by WB 4101 (pA2 9.0), 5‐methyl‐urapidil (pA2 8.6), phentolamine (pA2 7.6), benoxathian (pA2 8.5), spiperone (pA2 7.3), indoramin (pA2 8.2) and BMY 7378 (pA2 6.6). These values correlated best with published pKi values for their displacement of [3H]‐prazosin binding on membranes expressing cloned α1c‐adrenoceptors and poorly with values from cloned α1b‐ and α1dadrenoceptors.
The good correlation between the functional data on the prostate and the binding data on the expressed α1c‐subtype clone for the affinities of the competitive antagonists suggests that they are the same subtype. As the expressed α1c‐adrenoceptor clone corresponds to the α1A‐adrenoceptor expressed in tissues, contraction of the human prostate to noradrenaline is therefore mediated by an α1A‐adrenoceptor.
Characterization of neuropeptide Y (NPY) receptors in human cerebral arteries with selective agonists and the new Y1 antagonist BIBP 3226
Authors: Abounader Roger , Villemure Jean‐Guy , Hamel Edith 
Published: July 2012

We have characterized pharmacologically the receptor subtype(s) responsible for the neuropeptide Y (NPY)‐induced vasoconstriction in human cerebral arteries. NPY, PYY and several of their derivatives with well defined affinities at the known Y1 and Y2 receptor subtypes were used. Moreover, we tested the ability of the new Y1 receptor antagonist, BIBP 3226, to antagonize the NPY‐induced cerebral vasoconstriction.
NPY, PYY and their agonists with high affinities at the Y1 receptor subtype ([Leu31‐Pro34]‐NPY and [Leu31‐Pro34]‐PYY) elicited strong, long lasting and concentration‐dependent contractions of human cerebral arteries. Compounds with Y2 affinity such as PYY3–36 or NPY13–36 either elicited a submaximal contraction at high concentrations or failed to induce any significant vasomotor response. Also, the application of NPY or the specific Y1 agonist, [Leu31‐Pro34]‐NPY, to human cerebral vessels pretreated with the Y1 agonist, NPY13–36, resulted in contractile responses identical to those obtained when these compounds were tested without prior application of NPY13–36.
The order of agonist potency at the human cerebrovascular receptor was: [Leu31‐Pro34]‐NPY= [Leu31‐Pro34]‐PYY≤NPY>PYY>PYY3–36> > >NPY13–36, which corresponded to that reported previously at the neuronal and vascular Y1 receptors.
Increasing concentrations (10−9‐10−6m) of the Y1 receptor antagonist, BIBP 3226, to human cerebral vessels caused a parallel and rightward shift in the NPY dose‐response curves without any significant change in the maximal contractile response. The calculated pA2 was 8.52±0.13, a value compatible with the reported affinity at the rodent and human Y1 receptor.
We conclude that Y1 receptors exclusively, mediate the NPY‐induced contraction in human cerebral arteries and we show that BIBP 3226 is a potent and competitive antagonist of this Y1‐mediated vasoconstriction.
Effect of interleukin‐4 and interleukin‐10 on leucocyte migration and nitric oxide production in the mouse
Authors: Perretti Mauro , Szabó Csaba , Thiemermann Christoph 
Published: July 2012

The effect of systemic treatment of mice with murine recombinant interleukin‐4 (IL‐4) or interleukin‐10 (IL‐10) on neutrophil infiltration into a specific tissue site and nitric oxide (NO) production from peritoneal macrophages was investigated.
Intravenously (i.v.) administered IL‐4 (0.01–10 μg per mouse, approximately 0.3–300 μg kg−1, i.v.) and IL‐10 (0.01‐1 μg per mouse, approximately 0.3–30 μg kg−1, i.v.) dose‐dependently inhibited neutrophil accumulation into a 6‐day‐old murine air‐pouch induced by local application of interleukin‐1β (IL‐1β, 5 ng), with approximate ED50s of 0.35 and 0.90 μg, respectively. Neither IL4 (1 μg, 30 μg kg−1, i.v.) nor IL‐10 (1 μg, 30 μg kg−1, i.v.) prevented leucocyte accumulation in the mouse air‐pouches when interleukin‐8 (IL‐8, 1μg.) was used as chemoattractant. Similarly, neither cytokine had any effect on the in vitro up‐regulation of CD11b antigen on the surface of murine circulating neutrophils.
Treatment of mice with lipopolysaccharide (LPS, 0.3 mg kg−1, i.p.) caused an increase in the formation of NO (measured as nitrite accumulation) in the supernatant of peritoneal macrophages ex vivo. Pretreatment of mice with IL4 (0.01‐1 μg i.v., 20 min before LPS), but not with IL‐10 (1 μg i.v., 20 min before LPS), caused a dose‐dependent reduction in this LPS‐stimulated formation of nitrite by peritoneal macrophages ex vivo.
Activation of murine macrophages with LPS (1 μg ml−1 for 24 h) in vitro caused a significant increase in nitrite release in the supernatant of these cells. Pretreatment of either J774.2 or peritoneal macrophages with IL4 (0.1‐1 μg ml−1, 20 min before LPS), but not with IL‐10 (1 μg ml−1, 20 min before LPS) caused a concentration‐related attenuation of this LPS‐stimulated nitrite formation.
Thus, both IL‐4 and IL‐10 inhibit the migration of leucocytes (stimulated by IL‐1β) in vivo; IL‐4 (but not IL‐10) inhibits the induction of NO synthase caused by LPS in murine macrophages in vitro and ex vivo.
Characterization of the functional muscarinic receptors in the rat urinary bladder
Authors: Longhurst Penelope A. , Leggett Robert E. , Briscoe Janice A.K. 
Published: July 2012

Muscarinic receptors mediating contraction of the rat urinary bladder were characterized functionally in vitro by use of atropine, 4‐diphenylacetoxy‐N‐methylpiperidine methiodide (4‐DAMP methiodide), 4‐diphenylacetoxy‐N‐(2‐chloroethyl)‐piperidine hydrochloride (4‐DAMP mustard), hexahydro‐sila‐diphenidol hydrochloride (HHSiD), the p‐fluoro analogue of hexahydro‐sila‐diphenidol hydrochloride (p‐F‐HHSiD), methoctramine, and pirenzepine.
(+)‐cis‐Dioxolane contracted bladder strips in a concentration‐dependent manner with an EC50 of 0.169±0.018 μm and an Emax of 7.84±0.67 g.
Concentration‐effect curves to (+)‐cis‐dioxolane were shifted to the right in the presence of the antagonists in a concentration‐dependent manner. The rank order of antagonist affinities against the (+)‐cis‐dioxolane response was (pA2 values in the parentheses) atropine (9.28)≥4‐DAMP methiodide (9.04)>HHSiD (8.01) > p‐F‐HHSiD (7.28)=pirenzepine (7.12)≥ methoctramine (6.77, 7.25). The profile resembles that associated with the M3 receptor subtype.
Atropine, 4‐DAMP methiodide, pirenzepine, and methoctramine had no effects on the contractile response to 120 mM KCl. However, HHSiD and p‐F‐HHSiD decreased the response to KCl, and 4‐DAMP mustard increased it.
Contractile responses to electrical field stimulation (1–32 Hz, 0.05 ms pulse duration) were biphasic in nature. The tonic response was suppressed more than the phasic response by all antagonists except methoctramine. The suppression was not always concentration‐dependent, and did not seem to be related to antagonism of any one receptor subtype.
Our findings are consistent with the minority M3 receptors mediating the contractile response to muscarinic stimulation by (+)‐cis‐dioxolane in the rat bladder.
SMS 201–995‐induced stimulation of gastric acid secretion via the dorsal vagal complex and inhibition via the hypothalamus in anaesthetized rats
Authors: Yoneda Masashi , Taché Yvette 
Published: July 2012

SMS 201–995, a somatostatin analogue which interacts with highest affinities at somatostatin receptor subtypes 5 > 2 ≥ 3, was microinjected into selective brain sites and its influence on pentagastrin (10 μg kg−1 h−1, i.v.) ‐stimulated gastric acid secretion was investigated in rats anaesthetized with urethane. Gastric acid secretion was measured by flushing the stomach with saline through a gastric cannula every 10 min.
SMS 201–995 microinjected into the dorsal vagal complex (DVC, 7, 15, 30 and 60 ng) dose‐dependently increased pentagastrin‐stimulated gastric acid secretion. The peak acid response was reached within 20 min and returned to basal level 50 min post‐injection. SMA 201–995 (30 ng) microinjected into the surrounding area or the central amygdala did not modify pentagastrin‐stimulated acid secretion.
SMS 201–995 injected into the lateral ventricle (i.c.v., 100, 200, or 300 ng), paraventricular nucleus (PVN) or lateral hypothalamus (LH) (7.5, 15, or 30 ng) dose‐dependently inhibited pentagastrin‐stimulated gastric acid secretion. SMS 201–995 (30 ng) microinjected into the area surrounding the PVN or LH did not modify the acid secretion response to pentagastrin.
Vagotomy prevented the effects of SMS 201–995 (30 ng) microinjected into the DVC and LH.
Spinal cord transection abolished the inhibitory action of SMS 201–995 (30 ng) microinjected into the PVN but not the LH.
These results demonstrate that SMS 201–995 acts in the DVC to enhance and in the LH and PVN to inhibit pentagastrin‐stimulated gastric acid secretion. The action is mediated through vagal (DVC, LH) or spinal (PVN) pathways. The site specific pattern of acid responses to SMS 201–995 may be linked to the distribution of receptor subtypes at these sites that convey the different biological actions of somatostatin.
Similar coronary vascular effects in the rat perfused heart of platelet‐activating factor structural analogues with agonist and antagonist properties
Authors: Man Ricky Y.K. , Kinnaird Anne A.A. 
Published: July 2012

Selective blockade of platelet‐activating factor (PAF) receptor subtypes by PAF receptor antagonists has been demonstrated. However, selective activation of PAF receptor subtypes by PAF receptor agonists has not been reported.
When structural analogues of PAF that have been shown to possess either agonist or antagonist effects were administered by a bolus injection in the rat perfused heart, they all showed agonist effects. Lower amounts produced vasodilatation while higher amounts produced vasodilatation followed by vasoconstriction. These coronary vascular effects were typical of that observed with PAF. Lyso‐PAF did not show the same typical pattern of coronary vascular effect, confirming that the detergent effect of PAF structural analogues did not play a role in the coronary vascular effects. Other PAF antagonists, CV‐6209 and WEB 2170, also did not produce the PAF‐like response in the rat perfused heart.
The coronary vascular effects of hexanolamine‐PAF (H‐PAF, putative antagonist) and ethanolamine‐PAF (E‐PAF, agonist) were further studied. Pretreatment with FR‐900452 (a PAF receptor antagonist) or MK‐886 (a leukotriene synthesis inhibitor) significantly reduced the vasodilator and vasoconstrictor effects of H‐PAF and E‐PAF.
Pretreatment of rat perfused hearts with low concentrations of H‐PAF and E‐PAF blocked the response to PAF administration in a dose‐ and time‐dependent manner. However, the pretreatment with either H‐PAF or E‐PAF did not result in a coronary vascular effect expected of a PAF receptor agonist. These results were compatible with H‐PAF and E‐PAF behaving as PAF receptor antagonists.
In summary, our results demonstrate that several PAF structural analogues possess agonist action in the rat perfused heart. Like the coronary vascular effects of PAF, the effects of H‐PAF and E‐PAF were blocked by a PAF antagonist (FR‐900452) and a leukotriene synthesis inhibitor (MK‐886). This suggests that both H‐PAF and E‐PAF mediate their effect through activation of PAF receptors with a subsequent release of leukotrienes that produced vasodilatation and vasoconstriction. Furthermore, pretreatment of perfused hearts with these compounds blocked the response to PAF in these hearts. Thus these compounds can also behave like a PAF receptor antagonist. This latter action may be due to a gradual receptor inactivation or desensitization by the pretreatment of H‐PAF and E‐PAF through a PAF receptor agonist effect rather than being a PAF receptor antagonist.
Correlation of cyclic AMP accumulation and relaxant actions of salmeterol and salbutamol in bovine tracheal smooth muscle
Authors: Ellis Karen E. , Mistry Rajendra , Boyle John P. , Challiss R.A. John 
Published: July 2012

The ability of salmeterol to stimulate cyclic AMP accumulation and relaxation has been compared with that of salbutamol in bovine tracheal smooth muscle. In addition, the anti‐spasmogenic effects of these agents and their abilities to modulate histamine‐stimulated [3H]‐inositol phosphate accumulation have also been investigated.
In tissue strips, a close temporal correlation was found to exist between salmeterol (0.1 μm)‐induced relaxation of methacholine (500 nM)‐induced tone and cyclic AMP accumulation, both maximal reversal of induced tone (26.2 ± 6.0%) and maximal levels of cyclic AMP accumulation being achieved after 30–40 min. In contrast to salmeterol, salbutamol exerted greater and more rapid effects on both parameters. Maximal reversal of methacholine‐induced tone (79.3 ± 14.0%) and maximal levels of cyclic AMP accumulation were produced within 5 min.
Salmeterol‐induced cyclic AMP accumulation (EC50 = 5.3 [1.8–15.2] nM) and inhibition of histamine (0.1 mM)‐stimulated [3H]‐inositol phosphate accumulation (IC50=1.4 [0.3–6.3] nM) were both more potent than those induced by salbutamol (EC50= 169 [99–290] nM; IC50= 13.8 [7.0–27.4] nM). However, maximal effects exerted by each of these agents were similar in magnitude.
Anti‐spasmogenic effects were examined by β‐adrenoceptor agonist application to tissue strips prior to construction of spasmogen concentration‐effect curves. Both salmeterol and salbutamol exerted more marked inhibition of the contractile response induced by histamine than that induced by methacholine, salmeterol being the more potent agent, while salbutamol produced a greater maximal inhibitory effect.
The results demonstrate that salmeterol is a more potent agent than salbutamol and have highlighted a close temporal correlation between promotion of cyclic AMP accumulation and tissue relaxation stimulated by each agent when both parameters are measured under identical conditions.
Ginsenosides‐induced nitric oxide‐mediated relaxation of the rabbit corpus cavernosum
Authors: Chen Xiu , Lee Tony J.‐F. 
Published: July 2012

Ginsenosides, the active ingredients extracted from Panax ginseng, have been shown to promote nitric oxide (NO) release in bovine aortic endothelial cells. Since the endothelial cells and the perivascular nerves in penile corpus cavernosum contain NO synthase and an NO‐like substance has been shown to be released from these cells which relaxes corpus cavernosum, the possibility that ginsenosides may relax corpus cavernosum by releasing endogenous NO was examined.
With an in vitro tissue superfusion technique, ginsenosides (250, 500 and 750 μg ml−1) relaxed corpus cavernosum, concentration‐dependently.
Using an in vitro tissue bath technique, acetylcholine (ACh)‐induced relaxations were increased in the presence of ginsenosides (250 *μg ml−1).
Ginsenosides at 100 μg ml−1 significantly enhanced the tetrodotoxin (TTX)‐sensitive relaxation of corpus cavernosum elicited by transmural nerve stimulation.
The ginsenosides‐induced, ACh‐induced and ginsenosides‐enhanced transmural nerve stimulation‐elicited relaxations were significantly attenuated by NG‐nitro‐L‐arginine (100 μM) and oxyhaemoglobin (oxyHb; 5‐10jiM), and were enhanced by superoxide dismutase (SOD; 50u ml−1).
The relaxations and their attenuation by NG‐nitro‐L‐arginine and TTX were associated with increase and decrease in tissue cyclic GMP levels, respectively.
It is concluded that ginsenosides may release NO from endothelial cells, and enhance NO release from endothelial cells elicited by other vasoactive substances and from perivascular nitrergic nerves in the corpus cavernosum. These endothelial and neurogenic effects of ginsenosides in inducing relaxation of the corpus cavernosum may account for the aphrodisiac effect of Panax ginseng.
Suppression of eosinophil function by RP 73401, a potent and selective inhibitor of cyclic AMP‐specific phosphodiesterase: comparison with rolipram
Authors: Soilness John E. , Maslen Christopher , Webber Stephen , Foster Martyn , Raeburn David , Palfreyman Malcolm N. , Ashton Michael J. , Karlsson Jan‐Anders 
Published: July 2012

We have investigated the inhibitory potency of RP 73401, a novel, highly selective and potent inhibitor of cyclic AMP‐specific phosphodiesterase (PDE IV), against partially‐purified PDE isoenzymes from smooth muscle and the particulate PDE IV from guinea‐pig eosinophils. The inhibitory effects of RP 73401 on the generation of superoxide (.O2−), major basic protein (MBP) and eosinophil cationic protein (ECP) from guinea‐pig eosinophils have also been studied.
RP 73401 potently inhibited partially‐purified cyclic AMP‐specific phosphodiesterase (PDE IV) from pig aortic smooth muscle (IC50 = 1.2 nM); it was similarly potent against the particulate PDE IV from guinea‐pig peritoneal eosinophils (IC50 = 0.7 nM). It displayed at least a 19000 fold selectivity for PDE IV compared to its potencies against other PDE isoenzymes. Rolipram was approximately 2600 fold less potent than RP 73401 against pig aortic smooth muscle PDE IV (IC50 = 3162 nM) and about 250 times less potent against eosinophil PDE IV (IC50 = 186 nM).
Solubilization of the eosinophil particulate PDE IV increased the potency of rolipram 10 fold but did not markedly affect the potency of RP 73401. A similar (10 fold) increase in the PDE IV inhibitory potency of rolipram, but not RP 73401, was observed when eosinophil membranes were exposed to vanadate/glutathione complex (V/GSH).
Reverse transcription polymerase chain reaction (RT‐PCR), using primer pairs designed against specific sequences in four distinct rat PDE IV subtype cDNA clones (PDE IVA‐D), showed only mRNA for PDE IVD in guinea‐pig eosinophils. PDE IVD was also the predominant subtype expressed in pig aortic smooth muscle cells.
RP 73401 (Kiapp = 0.4 nM) was 4 fold more potent than (±)‐rolipram (Kiapp =1.7 nM) in displacing [3H]‐(±)‐rolipram from guinea‐pig brain membranes.
In intact eosinophils, RP 73401 potentiated isoprenaline‐induced cyclic AMP accumulation (EC50 = 79 nM). RP 73401 also inhibited leukotriene B4‐induced generation of O2− (IC50 = 25 nM), and the release of major basic protein (IC50‐ 115 nM) and eosinophil cationic protein (IC50 = 7nM). Rolipram was 3–14 times less potent than RP 73401.
Thus RP 73401 is a very potent and selective PDE IV inhibitor which suppresses eosinophil function suggesting that it may be a useful agent for the treatment of inflammatory diseases such as asthma. The greatly different inhibitory potencies of rolipram against PDE IV from smooth muscle and eosinophils (in contrast to the invariable effects of RP 73401) are unlikely to be attributable to diverse PDE IV subtypes but suggest distinct interactions of the two inhibitors with the enzyme.