bluuebunny/crossref_metadata_2025_split huggingface dataset:
Activation of potassium conductance by ophiopogonin‐D in acutely dissociated rat paratracheal neurones
Authors: Ishibashi Hitoshi , Mochidome Takanobu , Okai Junpei , Ichiki Hiroyuki , Shimada Hideaki , Takahama Kazuo 
Published: January 2005

The effect of ophiopogonin‐D (OP‐D), a steroidal glycoside and an active component of Bakumondo‐to, a Chinese herbal antitussive, on neurones acutely dissociated from paratracheal ganglia of 2‐week‐old Wistar rats was investigated using the nystatin‐perforated patch recording configuration.
Under current‐clamp conditions, OP‐D (10 μM) hyperpolarized the paratracheal neurones from a resting membrane potential of −65.7 to −73.5 mV.
At the concentration of 1 μM and above, OP‐D concentration‐dependently activated an outward current accompanied by an increase in the membrane conductance under voltage‐clamp conditions at a holding potential of −40 mV.
The reversal potential of the OP‐D‐induced current (IOP‐D) was −79.4 mV, which is close to the K+ equilibrium potential of −86.4 mV. The changes in the reversal potential for a 10 fold change in extracellular K+ concentration was 53.1 mV, indicating that the current was carried by K+.
The IOP‐D was blocked by an extracellular application of 1 mM Ba2+ by 59.0%, but other K+ channel blockers, including 4‐aminopyridine (3 mM), apamin (1 μM), charybdotoxin (0.3 μM), glibenclamide (1 μM), tolbutamide (0.3 mM) and tetraethylammonium (10 mM), did not inhibit the IOP‐D.
OP‐D also inhibited the ACh‐ and bradykinin‐induced depolarizing responses which were accompanied with firing of action potentials.
The results suggest that OP‐D may be of benefit in reducing the excitability of airway parasympathetic ganglion neurones and consequently cholinergic control of airway function and further, that the hyperpolarizing effect of OP‐D on paratracheal neurones via an activation of K+ channels might explain a part of mechanisms of the antitussive action of the agent.

British Journal of Pharmacology (2001) 132, 461–466; doi:10.1038/sj.bjp.0703818
Evidence for cocaine and methylecgonidine stimulation of M2 muscarinic receptors in cultured human embryonic lung cells
Authors: Yang Yinke , Ke Qingen , Cai Jingbo , Xiao Yong‐Fu , Morgan James P 
Published: January 2005

Muscarinic cholinoceptor stimulation leads to an increase in guanylyl cyclase activity and to a decrease in adenylyl cyclase activity. This study examined the effects of cocaine and methylecgonidine (MEG) on muscarinic receptors by measurement of cyclic GMP and cyclic AMP content in cultured human embryonic lung (HEL299) cells which specifically express M2 muscarinic receptors.
A concentration‐dependent increase in cyclic GMP production was observed in HEL299 cells incubated with carbachol, cocaine, or MEG for 24 h. The increase in cyclic GMP content was 3.6 fold for 1 μM carbachol (P<0.01), 3.1 fold for 1 μM cocaine (P<0.01), and 7.8 fold for 1 μM MEG (P<0.001), respectively. This increase in cyclic GMP content was significantly attenuated or abolished by the muscarinic receptor antagonist atropine or the M2 blocker methoctramine.
In contrast, cocaine, MEG, and carbachol produced a significant inhibition of cyclic AMP production in HEL299 cells. Compared to the control, HEL299 cells treated with 1 μM cocaine decreased cyclic AMP production by 30%. MEG and carbachol at 1 μM decreased cyclic AMP production by 37 and 38%, respectively. Atropine or methoctramine at 1 or 10 μM significantly attenuated or abolished the cocaine‐induced decrease in cyclic AMP production. However, the antagonists alone had neither an effect on cyclic GMP nor cyclic AMP production. Pretreatment of HEL299 cells with pertussis toxin prevented the cocaine‐induced reduction of cyclic AMP production.
Western blot analysis showed that HEL299 cells specifically express M2 muscarinic receptors without detectable M1 and M3. Incubation of HEL299 cells with cocaine, carbachol, and atropine did not alter the expression of M2 protein levels. However, the inducible isoform of nitric oxide synthase (iNOS) was induced in the presence of cocaine or carbachol and this induction was significantly attenuated after addition of atropine or methoctramine.
The present data show that cocaine and MEG significantly affect cyclic GMP and cyclic AMP production in cultured HEL299 cells. Our results also show that these effects result from the drug‐induced stimulation of M2 muscarinic receptors accompanied with no alterations of receptor expression. However, the induction of iNOS by cocaine may result in the increase in cyclic GMP production.

British Journal of Pharmacology (2001) 132, 451–460; doi:10.1038/sj.bjp.0703819
In vivo evidence for KCa channel opening properties of acetazolamide in the human vasculature
Authors: Pickkers Peter , Hughes Alun D , Russel Frans G M , Thien Theo , Smits Paul 
Published: January 2005

The selective carbonic anhydrase inhibitor acetazolamide is known to increase blood flow in several organs. Acetazolamide directly dilates isolated resistance arteries associated with activation of calcium‐activated potassium (KCa) channels. We examined both the presence and mechanism of the direct vascular action of acetazolamide in vivo in humans.
Forearm vasodilator responses of 30 healthy volunteers to infusion of placebo and increasing doses of acetazolamide (1‐3‐10 mg min−1 dl−1) into the brachial artery were recorded by venous occlusion plethysmography, before and after local administration of L‐NMMA (0.2 mg min−1 dl−1, an inhibitor of NO‐synthase, n=6), indomethacin (5.0 μg min−1 dl−1, an inhibitor of prostaglandin synthesis, n=6), glibenclamide (10 μg min−1 dl−1, an inhibitor of KATP channels, n=6), tetraethylammonium (0.1 mg min−1 dl−1, an inhibitor of KCa channels, n=6) or placebo (NaCl 0.9%, n=6). Lower dosages of acetazolamide did not affect vascular tone (n=6).
Acetazolamide infusions increased forearm blood flow from 2.41±0.17 to 2.99±0.18, 4.09±0.26 and 6.77±0.49 ml min−1 dl−1 in the infused forearm (P<0.001), with no significant changes in the non‐infused forearm, blood pressure or heart rate. Acetazolamide‐induced vasodilation was not inhibited by L‐NMMA, indomethacin, or glibenclamide but was significantly attenuated by TEA (vasodilation: 23±6, 82±19, 241±38% versus 27±8, 44±22, 42±35%).
We conclude that acetazolamide exerts a direct vasodilator effect in vivo in humans mediated by vascular KCa channel activation. This makes acetazolamide the first drug known that specifically modulates this channel.

British Journal of Pharmacology (2001) 132, 443–450; doi:10.1038/sj.bjp.0703825
Separation of cannabinoid receptor affinity and efficacy in delta‐8‐tetrahydrocannabinol side‐chain analogues
Authors: Griffin Graeme , Williams Stephanie , Aung Mie Mie , Razdan Raj K , Martin Billy R , Abood Mary E 
Published: January 2005

The activities of a number of side‐chain analogues of delta‐8‐tetrahydrocannabinol (Δ8‐THC) in rat cerebellar membrane preparations were tested.
The affinities of each compound for the CB1 receptor were compared by their respective abilities to displace [3H]‐SR141716A and their efficacies compared by stimulation of [35S]‐GTPγS binding.
It was found that the affinities varied from 0.19±0.03 nM for 3‐norpentyl‐3‐[6′‐cyano,1′,1′‐dimethyl]hexyl‐Δ8‐THC to 395±66.3 nM for 5′‐[N‐(4‐chlorophenyl)]‐1′,1′‐dimethyl‐carboxamido‐Δ8‐THC.
The efficacies of these compounds varied greatly, ranging from the very low efficacy exhibited to acetylenic compounds such as 1′‐heptyn‐Δ8‐THC and 4′‐octyn‐Δ8‐THC to higher efficacy compounds such as 5′‐(4‐cyanophenoxy)‐1′,1′‐dimethyl‐Δ8‐THC and 5′‐[N‐(4‐aminosulphonylphenyl)]‐1′,1′ dimethyl‐carboxamido Δ8‐THC. All agonist activities were antagonized by the CB1‐selective antagonist SR141716A.
It was found that a ligand's CB1 affinity and efficacy are differentially altered by modifications in the side‐chain. Decreasing the flexibility of the side‐chain reduced efficacy but largely did not alter affinity. Additionally, the positioning of electrostatic moieties, such as cyano groups, within the side‐chain also has contrasting effects on these two properties.
In summary, this report details the characterization of a number of novel Δ8‐THC analogues in rat cerebellar membranes. It provides the first detailed pharmacological analysis of how the inclusion of electrostatic moieties in the side‐chain and also how alteration of the side‐chain's flexibility may differentially affect a CB1 cannabinoid receptor ligand's affinity and efficacy.

British Journal of Pharmacology (2001) 132, 525–535; doi:10.1038/sj.bjp.0703827
β1‐Adrenoceptors compensate for β3‐adrenoceptors in ileum from β3‐adrenoceptor knock‐out mice
Authors: Hutchinson Dana S , Evans Bronwyn A , Summers Roger J 
Published: January 2005

This study examines β1‐, β2‐ and β3‐adrenoceptor (AR)‐mediated responses, mRNA levels and radioligand binding in ileum from β3‐AR knock‐out (−/−) (KO) and wild type (+/+) (FVB) mice.
In KO and FVB mice, SR59230A (100 nM) (β3‐AR antagonist) antagonized responses to (−)‐isoprenaline in both KO and FVB mice. (−)‐Isoprenaline mediated relaxation of ileum was antagonized weakly by ICI118551 (100 nM) (β2‐AR antagonist). Responses to (−)‐isoprenaline were more strongly antagonized by CGP20712A (100 nM) (β1‐AR antagonist), propranolol (1 μM) (β1‐/β2‐AR antagonist), carvedilol (100 nM) (non‐specific β‐AR antagonist), and CGP12177A (100 nM) (β1‐/β2‐AR antagonist) in ileum from KO than in FVB mice.
Responses to CL316243 (β3‐AR agonist) in ileum from FVB mice were antagonized by SR59230A (100 nM) but not by propranolol (1 μM) or carvedilol (100 nM). CL316243 was ineffective in relaxing ileum from KO mice.
CGP12177A had no agonist actions in ileum from either KO or FVB mice.
β1‐AR mRNA levels were increased 3 fold in ileum from KO compared to FVB mice. This was associated with an increased maximum number of β1‐/β2‐AR binding sites (Bmax). β2‐AR mRNA levels were unaffected while no β3‐AR mRNA was detected in KO mice.
In mouse ileum, β3‐ARs and to a lesser extent β1‐ARs are the predominant adrenoceptor subtypes mediating relaxation in ileum from FVB mice. In KO mice β1‐ARs functionally compensate for the lack of β3‐ARs, and this is associated with increased β1‐AR mRNA and levels of binding.

British Journal of Pharmacology (2001) 132, 433–442; doi:10.1038/sj.bjp.0703828
Improved diabetic syndrome in C57BL/KsJ‐db/db mice by oral administration of the Na+‐glucose cotransporter inhibitor T‐1095
Authors: Arakawa Kenji , Ishihara Tomomi , Oku Akira , Nawano Masao , Ueta Kiichiro , Kitamura Kazuyuki , Matsumoto Mamoru , Saito Akira 
Published: January 2005

The therapeutic effects of an orally active inhibitor of Na+‐glucose cotransporter (SGLT), T‐1095 (a derivative of phlorizin; 3‐(benzo[b]furan‐5‐yl)‐2′,6′‐dihydroxy‐4′‐methylpropiophenone 2′‐O‐(6‐O‐methoxycarbonyl‐β‐D‐glycopyranoside)) were examined in C57BL/KsJ‐db/db (db/db) mice, a genetic animal model of obese type 2 diabetes.
The higher renal SGLT activity in db/db mice than normoglycaemic C57BL/KsJ‐db/+m (db/+m) mice may support the rationale for using an SGLT inhibitor in the treatment regimen for type 2 diabetes. Both T‐1095 and its metabolite, T‐1095A, which had approximately 10 times more potency, effectively inhibited renal SGLT activity of these mice in vitro.
Single oral administration of T‐1095 (10, 30, 100 mg kg−1, p.o.) to db/db mice caused a dose‐dependent reduction in blood glucose levels and a concomitant increase in glucose excretion into urine. In contrast, T‐1095 only slightly affected blood glucose levels in db/+m mice.
Chronic administration of T‐1095 (0.1% w w−1 pellet chow, for 12 weeks) decreased blood glucose and haemoglobin A1C levels, and improved glucose intolerance in db/db mice. The age‐related decrease in plasma insulin levels was markedly inhibited and there was a 2.5 fold increase of insulin content in the pancreas of T‐1095‐treated db/db mice. Food consumption was not changed, while impaired body weight gain was ameliorated by T‐1095 treatment.
Both the development of albuminuria and the expansion of glomerular mesangial area in db/db mice were significantly suppressed by chronic T‐1095 treatment, indicating the prevention of the progression of diabetic nephropathy.
These results demonstrate that the SGLT inhibitor T‐1095 is able to improve the metabolic abnormalities and inhibit the development of diabetic complications in db/db mice. Thus, T‐1095 can be used for therapy of type 2 diabetic patients.

British Journal of Pharmacology (2001) 132, 578–586; doi:10.1038/sj.bjp.0703829
A N‐terminal PTHrP peptide fragment void of a PTH/PTHrP‐receptor binding domain activates cardiac ETA receptors
Authors: Schlüter Klaus‐Dieter , Katzer Christian , Piper Hans Michael 
Published: January 2005

Adult ventricular cardiomyocytes show an unusual structure‐function relationship for cyclic AMP‐dependent effects of PTHrP. We investigated whether PTHrP(1 – 16), void of biological activity on classical PTHrP target cells, is able to mimic the positive contractile effect of PTHrP(1 – 34), a fully biological agonist on cardiomyocytes.
Adult ventricular cardiomyocytes were paced at a constant frequency of 0.5 Hz and cell contraction was monitored using a cell‐edge‐detection system. Twitch amplitudes, expressed as per cent cell shortening of the diastolic cell length, and rate constants for maximal contraction and relaxation velocity were analysed.
PTHrP(1 – 16) (1 μmol l−1) mimicked the contractile effects of PTHrP(1 – 34) (1 μmol l−1). It increased the twitch amplitude from 5.33±0.72 to 8.95±1.10 (% dl l−1) without changing the kinetic of contraction.
PTH(1 – 34) (10 μmol l−1) affected the positive contractile effect of PTHrP(1 – 34), but not that of PTHrP(1 – 16).
RpcAMPS (10 μmol l−1) inhibited the positive contractile effect of PTHrP(1 – 34), but not that of PTHrP(1 – 16).
The positive contractile effect of PTHrP(1 – 16) was antagonized by the ETA receptor antagonist BQ123.
Sarafotoxin 6b and PTHrP(1 – 16), but not PTHrP(1 – 34), replaced 3H‐BQ123 from cardiac binding sites.
We conclude that N‐terminal PTHrP peptides void of a PTH/PTHrP‐receptor binding domain are able to bind to, and activate cardiac ETA receptors.

British Journal of Pharmacology (2001) 132, 427–432; doi:10.1038/sj.bjp.0703830
Evidence for expression and function of phosphodiesterase type 5 (PDE‐V) in rat resistance arteries
Authors: Sampson L J , Hinton J M , Garland C J 
Published: January 2005

Evidence is provided for expression and a functional role for phosphodiesterase type V (PDE‐V) in the rat isolated small mesenteric artery. The reverse transcription polymerase chain reaction (RT – PCR) demonstrated mRNA for PDE‐V, while Western blotting and immunocytochemical studies showed corresponding protein expression. Smooth muscle relaxation to the nitric oxide donor, diethylamine NONOate (DEA NONOate; 1 nM – 10 μM; pEC50=6.7±0.3) was potentiated significantly by the specific inhibitor of PDE‐V, 4‐[[3,4‐(methylenedioxy)benzyl]amino]‐6‐chloroquinazoline (MBCQ; 1 μM; pEC50=10.5±0.04). These data show that PDE‐V is expressed in both the smooth muscle and endothelial cells of a resistance artery, and the enzyme can significantly influence nitric oxide‐evoked vasorelaxation.British Journal of Pharmacology (2001) 132, 13–17; doi:10.1038/sj.bjp.0703831
Differential modulation by GTPγS of agonist and inverse agonist binding to h5‐HT1Areceptors revealed by [3H]‐WAY100,635
Authors: Newman‐Tancredi Adrian , Verrièle Laurence , Millan Mark J 
Published: January 2005

The interaction of serotonergic ligands at human (h) 5‐HT1Areceptors expressed in Chinese hamster ovary cells was examined with the selective ‘neutral’ 5‐HT1Aantagonist [3H]‐WAY100,635. Its binding was saturable (KD=0.056 nM) with a Bmax(3.65 pmol mg−1) significantly higher than that of two other selective 5‐HT1Aradioligands: the partial agonist, [3H]‐S15535 (2.77 pmol mg−1) and the agonist, [3H]‐8‐OH‐DPAT (2.02 pmol mg−1).The influence of GTPγS (100 μM) on the binding affinity of 15 serotonergic agonists, partial agonists, antagonists and inverse agonists was investigated in competition binding experiments with [3H]‐WAY100,635.Agonists, including 5‐HT, 8‐OH‐DPAT and buspirone, displayed biphasic isotherms which shifted to the right in the presence of GTPγS. In contrast, isotherms of theinverseagonists, methiothepin, (+)butaclamol and spiperone, were shifted to the left in the presence of GTPγS. Unlabelled WAY100,635 was the only ligand that was unaffected by GTPγS, consistent with ‘neutral’ antagonist properties.The magnitude of affinity changes induced by GTPγS for 13 ligands was highly correlated (r=0.98) with their efficacy (positive and negative) previously determined by [35S]GTPγS binding.In contrast, the napthylpiperazine derivative and high efficacy agonist, S14506, displayed only a modest GTPγS shift, in accordance with previous indications of ‘atypical’ binding properties of this ligand. A further full agonist, S14671, which is chemically closely‐related to S14506, also displayed a minimal GTPγS shift, underpinning this observation.In conclusion, [3H]‐WAY100,635 constitutes a useful neutral antagonist radioligand for the characterization of drug actions at h5‐HT1Areceptors. GTPγS‐induced affinity changes of agonist and inverse agonist competition isotherms generally correlate well with ligand efficacy, with the notable exception of two chemically‐similar agents, S14506 and S14671, which are efficacious agonists, yet relatively insensitive to h5‐HT1Areceptor/G‐protein coupling changes.British Journal of Pharmacology(2001)132, 518–524; doi:10.1038/sj.bjp.0703832
Contractile actions of proteinase‐activated receptor‐derived polypeptides in guinea‐pig gastric and lung parenchymal strips: evidence for distinct receptor systems
Authors: Saifeddine M , Al‐Ani B , Sandhu S , Wijesuriya S J , Hollenberg M D 
Published: January 2005

We have measured the contractile activities and relative potencies (EC50s) of six thrombin PAR1 receptor‐derived receptor‐activating peptides (PAR‐APs): AparafluroFRChaCit‐y‐NH2 (Cit‐NH2); SFLLRNP(P7); SFLLRNP‐NH2 (P7‐NH2); SFLLR (P5); SFLLR‐NH2 (P5‐NH2); TFLLR‐NH2 (TF‐NH2) and a PAR2 receptor activating peptide [SLIGRL‐NH2 (SL‐NH2)] (a) in a guinea‐pig lung peripheral parenchymal strip preparation and (b) in a gastric longitudinal smooth muscle preparation.
The relative potencies of the PAR‐APs in the lung preparation (Cit‐NH2≅TF‐NH2≅P5‐NH2>P7≅P5≅P7‐NH2; SL‐NH2 not active) differed appreciably from their relative potencies in the gastric preparation: Cit‐NH2≅TF‐NH2≅P7‐NH2≅P5‐NH2>P7≅percnt;SL‐NH2.
The contractile actions of the PAR1‐selective peptide, TF‐NH2 in the gastric preparation were entirely dependent on extracellular calcium and were blocked by tyrosine kinase inhibitors (genistein, tyrphostin 47/AG213, PP1) and by the cyclooxygenase inhibitor, indomethacin, whereas in the lung preparation, the PAR1‐mediated contractile response was only partially dependent on extracellular calcium and was refractory to the actions of either tyrosine kinase inhibitors or indomethacin.
Partial sequencing of the PAR cDNAs detected by RT – PCR both in whole lung and in the peripheral parenchymal strip bioassay tissue demonstrated the presence of both PAR1 and PAR2 mRNA; the expression of PAR2 was detected by immunohistochemistry.
The data point to the presence of distinct receptor systems for the PAR1‐APs in guinea‐pig lung parenchymal and gastric smooth muscle and indicate that PAR2 does not regulate contractile activity in peripheral parenchymal guinea‐pig lung tissue

British Journal of Pharmacology (2001) 132, 556–566; doi:10.1038/sj.bjp.0703839
Effect of chronic morphine treatment on α2‐adrenoceptor mediated autoinhibition of transmitter release from sympathetic varicosities of the mouse vas deferens
Authors: Karunanithi Shanker , Lavidis Nickolas A 
Published: January 2005

The effect of chronic morphine treatment (CMT) on sympathetic innervation of the mouse vas deferens and on α2‐adrenoceptor mediated autoinhibition has been examined using intracellular recording of excitatory junction potentials (EJPs) and histochemistry.
In chronically saline treated (CST) preparations, morphine (1 μM) and the α2‐adrenoceptor agonist (clonidine, 1 μM) decreased the mean amplitude of EJPs evoked with 0.03 Hz stimulation by 81±8% (n=16) and 92±6% (n=7) respectively. In CMT preparations, morphine (1 μM) and clonidine (1 μM) decreased mean EJP amplitude by 68±8% (n=7) and 79±8% (n=7) respectively.
When stimulating the sympathetic axons at 0.03 Hz, the mean EJP amplitude recorded from smooth muscles acutely withdrawn from CMT was four times greater than for CST smooth muscles (40.7±3.8 mV, n=7 compared with 9.9±0.3 mV, n=7).
Part of the increase in mean EJP amplitude following CMT was produced by a 31% increase in the density of sympathetic axons and varicosities innervating the smooth muscle.
Results from the present study indicate that the effectiveness of α2‐adrenoceptor mediated autoinhibition is only slightly reduced in CMT preparations. Most of the cross tolerance which develops between morphine, clonidine and α2‐adrenoceptor mediated autoinhibition occurs as a consequence of increased efficacy of neuromuscular transmission which is produced by an increase in the probability of transmitter release and an increase in the density of sympathetic innervation.

British Journal of Pharmacology (2001) 132, 403–410; doi:10.1038/sj.bjp.0703842
Stereoselective effects of the enantiomers of a new local anaesthetic, IQB‐9302, on a human cardiac potassium channel (Kv1.5)
Authors: González T , Longobardo M , Caballero R , Delpón E , Sinisterra J V , Tamargo J , Valenzuela C 
Published: January 2005

The N‐substituent of IQB‐9302 has the same number of carbons as bupivacaine, but it exhibits a different spatial localization (n‐butyl vs cyclopropylmethyl). Thus, the study of the effects of IQB‐9302 enantiomers on hKv1.5 channels will lead to a better knowledge of the determinants of stereoselective block.
The effects of the IQB‐9302 enantiomers were studied on hKv1.5 channels stably expressed in Ltk− cells using the whole‐cell configuration of the patch‐clamp technique. Drug molecular modelling was performed using Hyperchem software.
Block induced by IQB‐9302 was stereoselective with the R(+) enantiomer being 3.2‐fold more potent than the S(−) one (KD of 17.8±0.5 μM vs 58.6±4.0 μM).
S(−)‐ and R(+)IQB‐9302 induced‐block was time‐ and voltage‐dependent consistent with an electrical distance from the cytoplasmic side of 0.173±0.022 (n=12) and 0.181±0.018 (n=10), respectively.
Potency of block of pipecoloxylidide local anaesthetics was linearly related to the length between the cationic tertiary amine and the end of the substituent.
Molecular modelling shows that only when S(−) and R(+) enantiomers are superimposed by their aromatic ring, their N‐substituents are in opposite directions, which can explain the stereospecific block induced by bupivacaine and IQB‐9302 with hKv1.5 channels.
These results suggest that: (a) IQB‐9302 enantiomers block the open state of hKv1.5 channels, and (b) the length of the N‐substituent in these local anaesthetics and not its volume determines the potency and degree of their stereoselective hKv1.5 channel block.

British Journal of Pharmacology (2001) 132, 385–392; doi:10.1038/sj.bjp.0703844