bluuebunny/crossref_metadata_2025_split huggingface dataset:
Selectivity profile of the novel muscarinic antagonist UH‐AH 37 determined by the use of cloned receptors and isolated tissue preparations
Authors: Wess J. , Lambrecht G. , Mutschler E. , Brann M.R. , Dörje F. 
Published: July 2012

Functional in vitro experiments were carried out to determine the antimuscarinic potencies of the pirenzepine derivative UH‐AH 37 (6‐chloro‐5,10‐dihydro‐5‐[(1‐methyl‐4‐piperidinyl)acetyl]‐11H‐dibenzo‐[b,e] [1,4] diazepine‐11‐one hydrochloride) at M1 muscarinic receptors of rabbit vas deferens, M2 receptors of rat left atria and M3 receptors of rat ileum. Furthermore, N‐[3H]‐methylscopolamine competition binding experiments were performed to obtain its affinities for the five cloned human muscarinic receptors (m1‐m5) stably expressed in CHO‐K1 cells. Pirenzepine served as a reference drug throughout all experiments.
In all preparations used, UH‐AH 37 interacted with muscarinic receptors in a fashion characteristic of a simple competitive antagonist.
In the functional studies, UH‐AH 37, like pirenzepine, showed high affinity for M1 (pA2 8.49) and low affinity for M2 muscarinic receptors (pA2 6.63). In contrast to pirenzepine, UH‐AH 37 also displayed high affinity for M3 receptors (pA2 8.04).
In agreement with its functional profile, UH‐AH 37 bound with highest affinity to m1 (pKi 8.74) and with lowest affinity to m2 receptors (pKi 7.35). Moreover, it showed a 7 fold higher affinity for m3 (pKi 8.19) than for m2 receptors, whereas pirenzepine bound to both receptors with low affinities.
The binding affinity of UH‐AH 37 for m4 and m5 receptors (pKi 8.32 for both receptors) was only ca. 2.5 fold lower than that for m1 receptors, while the corresponding affinity differences were 6 and 13 fold in case of pirenzepine.
In conclusion, the receptor selectivity profile of UH‐AH 37 differs clearly from that of its parent compound, pirenzepine, in both functional and radioligand binding studies, the major characteristics being its pronounced M2 (m2)/M3 (m3) selectivity. UH‐AH 37 thus represents a useful tool for the further pharmacological characterization of muscarinic receptor subtypes.
Ageing is associated with increased 5‐HT2‐receptor affinity and decreased receptor reserve in rat isolated coronary arteries
Authors: Nyborg Niels C. Berg 
Published: July 2012

The 5‐hydroxytryptamine (5‐HT)‐receptor subtype and affinity for 5‐HT was determined in large and small coronary arteries isolated as ring segments from the proximal and distal part of the left coronary artery of 3 month (young) and 2‐year old (old) rats.
Ketanserin induced a rightward shift of the 5‐HT concentration‐response curve in both proximal and distal coronary arteries from young rats. The slopes of the Schild‐plots were indistinguishable from unity and the estimated pA2 values were 9.11 and 9.27 for proximal and distal coronary arteries, respectively. These data indicate a homogeneous population of 5‐HT2‐like receptors in the coronary arteries.
The contractile effect of 5‐HT as well as the sensitivity to 5‐HT was greater in proximal and distal coronary arteries from old than from young rats.
The apparent 5‐HT2‐receptor affinity, −log(KA[m]), and fractional receptor‐occupancy for relative responses between 10% and 90% of maximum was determined by partial irreversible inhibition of the 5‐HT2‐receptors with phenoxybenzamine.
Ageing was associated with an increase in 5‐HT2‐receptor affinity for 5‐HT in both proximal and distal coronary arteries, whereas the fractional receptor occupancy for half‐maximal response to 5‐HT decreased with age.
5‐HT2‐receptor affinity for 5‐HT could account for the 5‐HT sensitivity of distal coronary arteries in both young and old rats but not in proximal coronary arteries as the slope of the regression line of plots of 5‐HT2‐receptor affinity vs. sensitivity was indistinguishable from unity in only the distal vessels.
The 5‐HT2‐receptor affinity for 5‐HT was linearly correlated to the fractional receptor occupancy for half maximal response, suggesting that the 5‐HT2‐receptor reserve or density down‐regulates the receptor affinity for 5‐HT.
The results indicate that the increase in 5‐HT sensitivity and contractile effect in rat coronary arteries rely upon an increase in both 5‐HT2‐receptor agonist affinity and efficiency of the excitation‐contraction coupling process in the vascular smooth muscle.
BAY u3405, a potent and selective thromboxane A2 receptor antagonist on airway smooth muscle in vitro
Authors: McKenniff M.G. , Norman P. , Cuthbert N.J. , Gardiner P.J. 
Published: July 2012

BAY u3405 (3(R)‐[[(4‐fluorophenyl) sulphonyl]amino]‐1,2,3,4‐tetrahydro‐9H‐carbazole‐9‐propanoic acid) has been evaluated on airway smooth muscle, from a number of species including man, for its thromboxane A2 (TXA2) antagonist activity.
BAY u3405 was a potent, and competitive, antagonist of the TXA2‐mimetic U46619‐induced contractions of human, guinea‐pig, rat and ferret airway smooth muscle with pA2 values between 8.0 and 8.9 and with no inherent contractile activity (10−9–10−4 m).
The TXA2 antagonist activity of BAY u3405 was stereoselective. Its (S)‐enantiomer, BAY u3406, was approximately 50 fold less effective against U46619 on guinea‐pig and human airway smooth muscle.
BAY u3405 also competitively antagonized contractions of guinea‐pig airway smooth muscle induced by prostaglandin D2 (PGD2) or its metabolite 9α, 11β‐PGF2. On human and ferret airway smooth muscle it abolished contractions induced by PGD2, PGF2α and 16, 16‐dimethyl‐PGE2.
A high concentration (10−6 m) of BAY u3405 had no effect on the contraction, or relaxation, of airway smooth muscle induced by a range of other agonists, nor did BAY u3405 have any effect on other prostanoid receptor types (DP, EP1, EP2, FP or IP).
BAY u3405, in contrast to some other TXA2 antagonists, is a potent and selective antagonist on a wide range of airways including human. This high affinity, and the oral activity of the compound described elsewhere, suggest it may be an appropriate tool to investigate the role of prostanoids in airway diseases such as asthma.
The change in the threshold for short‐term desensitization in isolated smooth muscle cells showing an all‐or‐none response to acetylcholine
Authors: Mita Mitsuo , Uchida Masaatsu K. 
Published: July 2012

Isolated smooth muscle cells from guinea‐pig taenia caecum were prepared by collagenase digestion. The cells showed an all‐or‐none response to acetylcholine (ACh) under our experimental conditions.
Desensitized cells showed an all‐or‐none response but required a higher concentration of ACh for induction of contraction, indicating that the desensitization was due to a change in the threshold concentration.
In [3H]‐quinuclidinyl benzilate ([3H]‐QNB) binding to the desensitized cells, KD and Bmax were not significantly different from those estimated in the control cells. The competitive inhibition curve for specific binding of [3H]‐QNB by ACh in the desensitized cells was in agreement with that of control cells.
The ACh‐stimulated increase of the 45Ca2+ influx was very rapid and correlated well with the contraction of the cells. The concentrations of ACh inducing the maximal 45Ca2+ influx were increased by desensitization.
These results indicated that although the binding of ACh to the receptor was not changed by desensitization, the threshold concentration of ACh for their contraction was raised by desensitization, and the 45Ca2+ influx accompanying the contraction was shifted to the side of high concentration of ACh.
These results suggest that the development of short‐term desensitization is due to an uncoupling of the receptor from the mechanism for initiation of the contraction.
Response of rabbit ear artery to endothelin‐1 during cooling
Authors: Monge L. , García‐Villalón A.L. , Montoya J.J. , García J.L. , Gómez B. , Diéguez G. 
Published: July 2012

The effects of cooling on the response of rabbit central ear artery to endothelin‐1 and the role of the endothelium in these effects were studied in 2 mm long cylindrical arterial segments.
Concentration‐response curves for endothelin‐1 (10−10–3 × 10−7 m) were recorded isometrically in arteries with and without endothelium at 37°C and during cooling (24°C). To analyze further the endothelial mechanisms of the response to endothelin‐1 during cooling, the effects of this peptide in the presence of NG‐nitro‐l‐arginine methyl ester (l‐NAME) (10−4 m) or meclofenamate (10−5 m) were also determined.
In every condition tested, endothelin‐1 produced a marked, concentration‐dependent arterial contraction. Sensitivity of intact arteries to this peptide was consistently lower at 24°C than at 37°C. At 37°C there were comparable responses of arteries with and without endothelium, but at 24°C arteries without endothelium showed a higher sensitivity than intact arteries to endothelin‐1.
l‐NAME (10−4 m) increased the maximal contraction at 37°C, and both the sensitivity and maximal contraction at 24°C of intact arteries to endothelin‐1. Meclofenamate (10−5 m) did not affect the arterial response to endothelin‐1.
Sensitivity of arteries with and without endothelium to nitroprusside (10−9–10−3 m) was significantly decreased during cooling, and endothelium removal did not affect the relaxation to this nitrovasodilator.
These results suggest that cooling decreases sensitivity of cutaneous arteries (ear artery) to endothelin‐1 probably by increasing the availability of endothelial nitric oxide.
Differentiation by hydroquinone of relaxations induced by exogenous and endogenous nitrates in non‐vascular smooth muscle: role of superoxide anions
Authors: Hobbs Adrian J. , Tucker John F. , Gibson Alan 
Published: July 2012

The influence of hydroquinone on relaxations induced by nitric oxide (NO), nitrovasodilator drugs, and non‐adrenergic, non‐cholinergic (NANC) field stimulation has been investigated in three tissues in which endogenous nitrates have been implicated in the NANC response; the mechanism of action of hydroquinone was also studied.
In mouse anococcygeus, hydroquinone (10–100 μm) produced a concentration‐dependent inhibition of relaxations induced by 15 μm NO. Hydroquinone, 100 μm, which reduced responses to NO by 85%, had no effect on relaxations induced by NANC field stimulation (10 Hz; 20s trains), hydroxylamine (10 μm), sodium nitroprusside (1 μm) or sodium azide (20 μm).
In guinea‐pig trachea, 100 μm hydroquinone reduced relaxations to 150 μm NO by 75%, but had no effect on those to NANC stimulation (10 Hz; 30 s trains) or sodium azide (5 μm).
In rat gastric fundus, 100 μm hydroquinone reduced relaxations to 1 μm NO by 85%, but had no effect on those to NANC stimulation (0.5 Hz; 15 s trains) or sodium azide (2 μm).
Superoxide dismutase (SOD; 50 u ml−1) had no effect on relaxations of the mouse anococcygeus in response to 15 μm NO or 10 Hz NANC stimulation. Further, the inhibition of responses to NO by hydroquinone was unaffected in the presence of SOD.
Hydroquinone (10–100 μm) failed to generate superoxide anions, as detected by a chemiluminescent assay. However, 100 μm hydroquinone, like SOD (50 u ml−1), produced almost complete inhibition of superoxide anion chemiluminescence induced by xanthine (500 μm): xanthine oxidase (0.07 u ml−1).
It is concluded that, in our system, hydroquinone inhibits NO by acting as a free radical scavenger rather than by generating superoxide anions. The ability of hydroquinone to block relaxations to NO, but not NANC stimulation, may suggest that the endogenous nitrate substance released by these NANC nerves may not be free NO, but may be an NO‐containing, or NO‐generating, molecule.
Pharmacological analysis of 5‐hydroxytryptamine effects on electrically stimulated human isolated urinary bladder
Authors: Corsi M. , Pietra C. , Toson G. , Trist D. , Tuccitto G. , Artibani W. 
Published: July 2012

5‐Hydroxytryptamine (5‐HT) is able to potentiate the contractions induced by electrical field stimulation of pieces of human isolated urinary bladder. On the basis of available selective 5‐HT agonists and antagonists, we have further investigated the receptors involved and their site of action.
5‐HT produced a concentration‐dependent increase of the contractile response to electrical field stimulation from 0.1 nm to μm. At higher concentrations (up to 100 μm) the effect decreased. These activities were mimicked by a variety of 5‐HT agonists, for which the following rank order of potency was found: 5‐HT > α‐methyl 5‐HT > 5‐methoxytryptamine > 5‐carboxamidotryptamine > 2‐methyl 5‐HT ≫ GR 43175. In addition the gastro‐prokinetics agents metoclopramide, cisapride and the 5‐HT3 antagonist ICS 205–930 behaved as 5‐HT agonists, their EC50 values being 2.3, 0.3, and 0.5 (μm) respectively.
The 5‐HT potentiating effect was resistant to antagonism by ondansetron (1 μm) and cyanopindolol (1 μm), selective 5‐HT3 and 5‐HT1A/1B antagonists respectively. The 5‐HT2 antagonists ketanserin (1 μm), spiperone (1 μm) and methysergide (1 μm) also showed a weak inhibitory activity. Methiothepin (0.1–1 μm) antagonized only the inhibitory effect of 5‐HT. Metoclopramide (0.1–1 μm), cisapride (0.01–0.1 μm) and ICS 205–930 (0.3–3 μm) all produced a rightward displacement of the 5‐HT response curve with concomitant reduction of the maximum response. The pA2 values calculated were 7.4, 8.5 and 7.0 respectively. The antagonism of metoclopramide was receptor specific and was not apparently related to interactions with dopaminergic activity since domperidone showed no antagonism of 5‐HT, and metoclopramide, itself, did not antagonize the potentiating effect of prostaglandin F2α.
The receptor involved in the potentiating effect of 5‐HT may be located prejunctionally because 5‐HT did not potentiate responses to acetylcholine (ACh) or electrical field stimulation with the parameters of direct muscle excitation. Also, since the 5‐HT potentiating effect was blocked by atropine, it may be attributed to a release of ACh.
This study suggests that in the human urinary bladder 5‐HT causes two opposite effects on the contractile response to electrical field stimulation. A potentiating effect at low concentrations due to an interaction with an atypical receptor, different from the classical 5‐HT1, 5‐HT2 or 5‐HT3 subtypes and an inhibitory effect at greater concentrations probably due to an interaction with 5‐HT1‐like receptors. The possibility that this atypical receptor possesses some characteristics of those found in other isolated preparations like guinea‐pig ileum, rat oesophagus and mouse embryo colliculi neurones is discussed.
Interleukin‐8 as a mediator of sympathetic pain
Authors: Cunha F.Q. , Lorenzetti B.B. , Poole S. , Ferreira S.H. 
Published: July 2012

The hyperalgesic effects of interleukin‐8 (IL‐8), interleukin‐1β (IL‐1β) and carrageenin were measured in a rat paw pressure test.
IL‐8 evoked a dose‐dependent hyperalgesia which was attenuated by a specific antiserum, the β‐adrenoceptor antagonists atenolol and propranolol, the dopamine1 receptor antagonist SCH 23390 and the adrenergic neurone‐blocking agent guanethidine. The hyperalgesia was not attenuated by the cyclo‐oxygenase inhibitor indomethacin or the IL‐1β analogue Lys‐d‐Pro‐Thr.
IL‐1β‐evoked hyperalgesia was attenuated by indomethacin and Lys‐d‐Pro‐Thr but not by atenolol or SCH 23390.
Carrageenin‐evoked hyperalgesia was attenuated by atenolol, indomethacin and anti‐IL‐8 serum. The effects of atenolol and anti‐IL‐8 serum were not additive. The effects of indomethacin and anti‐IL‐8 serum were additive: this combination abolished carrageenin‐evoked hyperalgesia.
A new biological activity of IL‐8 is described, namely the capacity to evoke hyperalgesia by a prostaglandin‐independent mechanism. IL‐8 is the first endogenous mediator to be identified as evoking hyperalgesia involving the sympathetic nervous system. Since IL‐8 is released by activated macrophages and endothelial cells it may be a humoral link between tissue injury and sympathetic hyperalgesia.
Effect of carbenoxolone on the biological activity of nitric oxide: relation to gastroprotection
Authors: Dembinska‐Kiec A. , Pallapies D. , Simmet Th. , Peskar B.M. , Peskar B.A. 
Published: July 2012

The interactions between carbenoxolone and nitric oxide (NO) were examined by investigating their effects on human platelet aggregation, on rat aortic strips precontracted by phenylephrine and on protection of rat gastric mucosa against ethanol‐induced injury.
Carbenoxolone (100–300 μm) caused a significant and concentration‐dependent potentiation of rat peritoneal neutrophil (RPN)‐, 3‐morpholino‐sydnonimine (SIN‐1)‐ or iloprost‐induced inhibition of platelet aggregation. Higher concentrations (500 μm) of carbenoxolone alone markedly inhibited platelet aggregation. Pretreatment with carbenoxolone (100–300 μm) antagonized the reversal of the RPN‐ or SIN‐1‐induced antiaggregatory effect by oxyhaemoglobin (10 μm).
Rat aortic strips with intact endothelium precontracted by phenylephrine (0.1–0.3 μm) were relaxed by carbenoxolone (100–300 μm) in a concentration‐dependent manner. Relaxations were abolished by mechanical removal of the endothelium or by incubation with methylene blue (10 μm) or NG‐nitro‐l‐arginine (l‐NNA, 100 μm). Sodium nitroprusside (10 nm)‐induced relaxations of endothelium‐denuded rat aortic strips were potentiated by carbenoxolone (100 μm).
The carbenoxolone (200 mg kg−1, p.o.)‐induced gastroprotection against ethanol was antagonized by l‐NNA (5–40 mg kg−1) in a dose‐dependent manner. Pretreatment of rats with indomethacin (10 mg kg−1, s.c.) increased the effect of l‐NNA.
The results suggest that the activity of carbenoxolone in the experimental systems tested is due to phosphodiesterase inhibition, although radical scavenging properties of the drug could contribute to some of the effects observed. In the rat gastric mucosa both increased prostaglandin levels and effects on the NO system could contribute to the protective action of carbenoxolone.
Effect of respiratory tract viral infection on murine airway β‐adrenoceptor function, distribution and density
Authors: Henry Peter J. , Rigby Paul J. , Mackenzie John S. , Goldie Roy G. 
Published: July 2012

The effects of a respiratory tract viral infection on β‐adrenoceptor density, distribution and function were investigated in murine airways.
Following intranasal inoculation of CBA/CaH mice with influenza A/PR‐8/34 virus, the virus proliferated rapidly in trachea (peak titres 2 days post‐inoculation) and lung (peak titres 4–6 days post‐inoculation). Respiratory tract viral infection was associated with a significant increase in lung weight (88% higher than control mice at day 6 post‐inoculation) that was related temporally to the development of peripheral lung inflammation and consolidation.
Analysis of specific binding of [125I]‐cyanopindolol to β‐adrenoceptors revealed that on days 2, 4 and 8 post‐inoculation with virus, mouse isolated tracheal sections contained, on average, 40% more β‐adrenoceptors than tracheal sections from time matched control mice. Subsequent quantitative autoradiographic studies demonstrated that this increase in total tracheal β‐adrenoceptors was due primarily to a 90% increase in the density of β‐adrenoceptors in the tracheal epithelium in virus‐infected mice.
In contrast, virus‐infection had no significant effect on the density of β‐adrenoceptors in tracheal airway smooth muscle, although within 2 days of inoculation with virus, mouse tracheal smooth muscle segments were approximately 2 fold less sensitive to the β‐adrenoceptor agonist, noradrenaline (mean pD2 = 6.57 ± 0.04, n = 24) and to the adenylyl cyclase‐activator forskolin (mean pD2 = 6.78 ± 0.04, n = 12) compared to segments from control mice (mean pD2 = 6.84 ± 0.06 for noradrenaline; mean pD2 = 7.03 ± 0.07 for forskolin). Similar values were obtained 8 days post‐inoculation. At day 2, but not day 8 post‐inoculation with virus, relaxation responses to theophylline were also marginally attenuated compared with controls.
Mouse isolated tracheal segments obtained 2 days after virus inoculation and segments from time‐matched control mice were equisensitive to the spasmogenic actions of the muscarinic cholinoceptor agonist, carbachol. However, tracheal segments from mice inoculated with virus were less responsive to carbachol on day 4 (mean pD2 = 6.45 ± 0.04, n = 8) and day 8 (mean pD2 = 6.45 ± 0.02, n = 12) compared to control preparations (day 4, mean pD2 = 6.73 ± 0.06, n = 8; day 8, mean pD2 = 6.65 ± 0.04, n = 12, P < 0.05). In contrast, endothelin‐1‐induced contractions of tracheal smooth muscle were not affected by virus‐infection.
These data demonstrate that respiratory tract viral infection can produce significant tissue‐selective changes in airway β‐adrenoceptor density as well as small reductions in airway smooth muscle muscarinic cholinoceptor and β‐adrenoceptor function.
Effects of porcine relaxin on contraction, membrane response and cyclic AMP content in rat myometrium in comparison with the effects of isoprenaline and forskolin
Authors: Osa Takuro , Inoue Hiroyoshi , Okabe Koji 
Published: July 2012

The longitudinal muscle from the uterus of oestrogen‐treated rats was quiescent in Mg‐free Krebs solution. Electrical stimulation generated phasic contraction, which was depressed to 35% and 18% by 50 mu and 150 mu porcine relaxin, respectively.
The phasic contractions were more strongly depressed to 26% by 50 mu relaxin in solution containing 0.6 mm Mg, and the depression lasted for more than 4 h after the removal of relaxin. During the persisting depression, raising the external Ca to 7.5 mm did not restore the contraction, but the contraction was restored by removal of Mg.
The depression of the phasic contraction by relaxin, examined in Mg‐free solution, was enhanced and reduced by pretreatment of the tissue with 0.6 mm Mg and 0.6 mm Mn, respectively, for about 15 min. In contrast, the depression of contraction by isoprenaline or forskolin was enhanced by pretreatment with either Mg or Mn.
The cellular content of cyclic AMP was measured in Krebs solution containing 0.6 mm Mg. The values were 1.24 (pmol mg−1 protein) in control solution, and 2.31 and 1.56 when the tissues were treated with 150 mu relaxin and 10−9 m isoprenaline, respectively.
The cyclic AMP production in response to 10−7 m forskolin measured in Mg‐free solution was enhanced when the tissue was pretreated with either 0.6 mm Mg or Mn for 15 min. The cyclic AMP production in response to 100 mu relaxin was increased when the tissue was pretreated with 0.6 mm Mg, and was unchanged by pretreatment with Mn. The cyclic AMP production in response to 10−9 m isoprenaline was unchanged by pretreatment with the divalent cations.
The membrane potential of the muscle was −60.8 mV in Krebs solution containing 0.3 mm Mg, and electrical stimulation induced an action potential which consisted of spike and plateau components. Application of 150 mu relaxin reduced the duration of the plateau; the contractions were progressively depressed. The resting membrane potential and membrane resistance were unchanged by application of 150 mu relaxin. The membrane was hyperpolarized by 2.8 mV, accompanied by a decrease in membrane resistance, when 10−9 m isoprenaline was applied.
Although there were several differences between the effects of relaxin and isoprenaline, it is probable that some process, which is cyclic AMP‐dependent, accelerated by Mg and depressed by Mn, is involved in the depressant action of relaxin on contraction.