bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cardiovascular actions of a novel NO‐independent guanylyl cyclase stimulator, BAY 41‐8543: in vivo studies
Authors: Stasch Johannes‐Peter , Dembowsky Klaus , Perzborn Elisabeth , Stahl Elke , Schramm Matthias 
Published: January 2005

BAY 41‐8543 is a novel non‐NO‐based stimulator of sGC. This study investigates the acute effects of BAY 41‐8543 on haemodynamics in anaesthetized rats and dogs, its long‐term effects in conscious hypertension rat models and its antiplatelet effects.
In anaesthetized dogs, intravenous injections of BAY 41‐8543 (3–100 μg kg−1) caused a dose‐dependent decrease in blood pressure and cardiac oxygen consumption as well as an increase in coronary blood flow and heart rate.
In anaesthetized normotensive rats, BAY 41‐8543 produced a dose‐dependent and long‐lasting blood pressure lowering effect after intravenous (3–300 μg kg−1) and oral (0.1–1 mg kg−1) administration. A dose‐dependent and long‐lasting decrease in blood pressure was also observed in conscious spontaneously hypertensive rats with a threshold dose of 0.1 mg kg−1 p.o. After 3 mg kg−1 the antihypertensive effect lasted for nearly 24 h. After multiple dosages, BAY 41‐8543 did not develop tachyphylaxis in SHR.
BAY 41‐8543 prolonged the rat tail bleeding time and reduced thrombosis in the FeCl3 thrombosis model after oral administration.
In a low NO, high renin rat model of hypertension, BAY 41‐8543 prevented the increase in blood pressure evoked by L‐NAME and reveals a kidney protective effect. In this model, the overall beneficial effects of BAY 41‐8543 manifested as both antiplatelet effect and vasodilatation were reflected in a significant reduction in mortality.
The pharmacological profile of BAY 41‐8543 suggests therefore that this compound has the potential to be an important research tool for in vivo investigations in the sGC/cGMP field and it also has the potential of being a unique clinical utility for treatment of cardiovascular diseases.

British Journal of Pharmacology (2002) 135, 344–355; doi:10.1038/sj.bjp.0704483
A study of P2X1 receptor function in murine megakaryocytes and human platelets reveals synergy with P2Y receptors
Authors: Vial Catherine , Rolf Michael G , Mahaut‐Smith Martyn P , Evans Richard J 
Published: January 2005

We have examined the role of ATP‐dependent P2X1 receptors in megakaryocytes (MKs) and platelets using receptor‐deficient mice and selective agonists.
α,β‐meATP‐ and ATP‐ evoked ionotropic inward currents were absent in whole‐cell recordings from MKs of P2X1−/− mice, demonstrating that the P2X receptor phenotype in MKs, and by inference, platelets, is due to expression of homomeric P2X1 receptors.
P2X1 receptor deficiency had no effect on MK (CD 41) numbers or size distribution, showing that it is not essential for normal MK development.
P2Y receptor‐stimulated [Ca2+]i responses were unaffected in MKs from P2X1−/− mice, however the inward cation current associated with Ca2+ release was reduced by ∼50%, suggesting an interaction between the membrane conductances activated by P2X1 and P2Y receptors.
Interaction between P2X1 and P2Y receptors in human platelets was also examined using [Ca2+]i recordings from cell suspensions. α,β‐meATP (10 μM) evoked a rapid transient P2X1 receptor‐mediated increase in [Ca2+]i, whereas ADP‐(10 μM) evoked P2Y receptor responses were slower, peaked at a higher level and remained elevated for longer periods. Co‐application of α,β‐meATP and ADP resulted in marked acceleration and amplification of the peak [Ca2+]i response.
We conclude that ionotropic P2X1 receptors may play a priming role in the subsequent activation of metabotropic P2Y receptors during platelet stimulation.

British Journal of Pharmacology (2002) 135, 363–372; doi:10.1038/sj.bjp.0704486
Mechanisms of nitric oxide generation from nitroglycerin and endogenous sources during hypoxia in vivo
Authors: Agvald Per , Adding L Christofer , Artlich Andreas , Persson Magnus G , Gustafsson Lars E 
Published: January 2005

Nitroglycerin (GTN), often used in conditions of cardiovascular ischaemia, acts through the liberation of nitric oxide (NO) and the local concentration of NO in the tissue is responsible for any biological effect. However, little is known about the way in which the concentration of NO from GTN and other NO‐donors is influenced by low oxygen tension in the target tissues.
To evaluate the impact of changes in oxygen tension in the metabolism of NO‐donors we measured exhaled NO in anaesthetized rabbits in vivo and expired NO and perfusate nitrite (NO2−) in buffer‐perfused lungs in situ. The impact of acute hypoxia on NO formation from GTN, isosorbide‐5‐mononitrate (ISMN), dissolved authentic NO, NO2− and NO generated from endogenous NO‐synthase (NOS) was studied in either model.
Acute hypoxia drastically increased exhaled NO concentrations from all NO‐donors studied, both in vivo and in the perfused lung. During similar conditions endogenous NO generation from NOS was strongly inhibited. The effects were most pronounced at less than 3% inspired oxygen.
The mechanisms for the increased NO‐formation during hypoxia seems to differ between GTN‐ and NO2−‐derived NO. The former phenomenon is likely due to diminished breakdown of NO.
In conclusion, hypoxic conditions preserve very high local NO concentrations generated from organic nitrates in vivo and we suggest that this might benefit preferential vasodilation in ischaemic tissue regions. Our findings point out the necessity to consider the influence of oxygen tension when studying the action of NO‐donors.

British Journal of Pharmacology (2002) 135, 373–382; doi:10.1038/sj.bjp.0704489
Histamine H3‐receptor‐mediated [35S]GTPγ[S] binding: evidence for constitutive activity of the recombinant and native rat and human H3 receptors
Authors: Rouleau A , Ligneau X , Tardivel‐Lacombe J , Morisset S , Gbahou F , Schwartz J ‐C , Arrang J ‐M 
Published: January 2005

Constitutive activity of the recombinant and native rat and human H3 receptors (H3Rs) was studied using H3R‐mediated [35S]GTPγ[S] binding and [3H]‐arachidonic acid release.
Ciproxifan, an inverse agonist at the rat H3R (rH3R), decreased [3H]arachidonic acid release from CHO cells expressing moderate densities (∼200–300 fmol mg−1 protein) of the human H3R (hH3R). This effect occurred with the same magnitude than at the rH3R.
The expression of the hH3R was associated with an increase in [35S]GTPγ[S] binding to membranes of CHO cells. Ciproxifan decreased [35S]GTPγ[S] binding to membranes of CHO (hH3R) cells. Both effects were correlated to receptor density and revealed that constitutive activity of the hH3R, although lower than that of the rH3R in this assay, was again observed at physiological densities (<500 fmol mg−1 protein). Ciproxifan was less potent at the human than the rat receptor, not only as an antagonist (Ki=45 nM), but also as an inverse agonist (EC50=15 nM).
Constitutive activity of the hH3R was also evidenced using inhibition of [35S]GTPγ[S] binding by unlabelled GTPγS. The expression of the hH3R generated a high affinity binding for GTPγS which was increased by imetit, but partially decreased by ciproxifan, therefore acting as a partial inverse agonist.
[35S]GTPγ[S] binding to rat brain membranes was decreased in several regions by thioperamide, ciproxifan and FUB 465, three inverse agonists at the H3R, whose effects were blocked by proxyfan, a neutral antagonist. [35S]GTPγ[S] binding was also decreased by an A1‐adenosine receptor inverse agonist, but remained unchanged in the presence of inverse agonists at D2/D3 dopamine, H1 and H2 histamine, α2‐adrenergic and δ opioid receptors.
In conclusion, the present study shows that the recombinant rat and human H3 receptors expressed at physiological densities display constitutive activity and suggests that constitutive activity of native H3Rs is one of the highest among G‐protein‐coupled receptors present in rat brain.

British Journal of Pharmacology (2002) 135, 383–392; doi:10.1038/sj.bjp.0704490
Disparate effects of non‐steroidal anti‐inflammatory drugs on apoptosis in guinea‐pig gastric mucous cells: inhibition of basal apoptosis by diclofenac
Authors: Ashton Miranda , Hanson Peter J 
Published: January 2005

Non‐steroidal anti‐inflammatory drugs (NSAIDs) induce apoptosis in gastrointestinal cancer cell lines. Similar actions on normal gastric epithelial cells could contribute to NSAID gastropathy. The present work therefore compared the actions of diclofenac, ibuprofen, indomethacin, and the cyclo‐oxygenase‐2 selective inhibitor, NS‐398, on a primary culture of guinea‐pig gastric mucous epithelial cells.
Cell number was assessed by staining with crystal violet. Apoptotic activity was determined by condensation and fragmentation of nuclei and by assay of caspase‐3‐like activity. Necrosis was evaluated from release of cellular enzymes.
Ibuprofen (250 μM for 24 h) promoted cell loss, and apoptosis, under both basal conditions and when apoptosis was increased by 25 μM N‐Hexanoyl‐D‐sphingosine (C6‐ceramide).
Diclofenac (250 μM for 24 h) reduced the proportion of apoptotic nuclei from 5.2 to 2.1%, and caused inhibition of caspase‐3‐like activity, without causing necrosis under basal conditions. No such reduction in apoptotic activity was evident in the presence of 25 μM C6‐ceramide.
The inhibitory effect of diclofenac on basal caspase‐3‐like activity was also exhibited by the structurally similar mefenamic and flufenamic acids (1–250 μM), but not by niflumic acid.
Inhibition of superoxide production by the cells increased caspase‐3‐like activity, but the inhibitory action of diclofenac on caspase activity remained. Diclofenac did not affect superoxide production.
Diclofenac inhibited caspase‐3‐like activity in cell homogenates and also inhibited human recombinant caspase‐3.
In conclusion, NSAIDs vary in their effect on apoptotic activity in a primary culture of guinea‐pig gastric mucous epithelial cells, and the inhibitory effect of diclofenac on basal apoptosis could involve an action on caspase activity.

British Journal of Pharmacology (2002) 135, 407–416; doi:10.1038/sj.bjp.0704497
Transient relaxation of rat mesenteric microvessels by ceramides
Authors: Czyborra Peter , Saxe Miriam , Fetscher Charlotte , Meyer zu Heringdorf Dagmar , Herzig Stefan , Jakobs Karl H , Michel Martin C , Bischoff Angela 
Published: January 2005

We have investigated the vasodilating effects of D‐erythro‐C2‐ceramide (C2‐ceramide) in methoxamine‐contracted rat mesenteric microvessels.
C2‐ceramide (10–100 μM) caused a concentration‐dependent, slowly developing relaxation which reached maximum values after ∼10 min and partially abated thereafter.
Endothelium removal or inhibitors of guanylyl cyclase (3 μM ODQ), protein kinase A (10 μM H7, 1 μM H89) and various types of K+ channels (10 μM BaCl2, 3 mM tetraethylammonium, 30 nM charybdotoxin, 30 nM iberiotoxin, 300 nM apamine, 10 μM glibenclamide) had only small if any inhibitory effects against C2‐ceramide‐induced vasodilation, but some of them attenuated vasodilation by sodium nitroprusside or isoprenaline. A combination of ODQ and charybdotoxin almost completely abolished C2‐ceramide‐induced vasodilation.
A second administration of C2‐ceramide caused a detectable but weaker relaxation. L‐threo‐C2‐ceramide (100 μM), which should not be a substrate to ceramide metabolism, had no biphasic time course. The ceramidase inhibitor (1S,2R)‐D‐erythro‐2‐(N‐myristoylamino)‐1‐phenyl‐1‐propanol (100 μM) alone caused some vasodilation, indicating vasodilation by endogenous ceramides, and also hastened relaxation by exogenous C2‐ceramide. The late‐developing reversal of C2‐ceramide‐induced vasodilation was absent when α‐adrenergic tone was removed by addition of 10 μM phentolamine.
We conclude that C2‐ceramide relaxes rat resistance vessels in an endothelium‐independent manner which is prevented only by combined inhibition of guanylyl cyclase and charybdotoxin‐sensitive K+ channels. The vasodilation abates with time partly due to desensitization of the ceramide response and partly due to metabolism of C2‐ceramide to an inactive metabolite.

British Journal of Pharmacology (2002) 135, 417–426; doi:10.1038/sj.bjp.0704498
Spontaneous phasic activity of the pig urinary bladder smooth muscle: characteristics and sensitivity to potassium channel modulators
Authors: Buckner Steven A , Milicic Ivan , Daza Anthony V , Coghlan Michael J , Gopalakrishnan Murali 
Published: January 2005

A hallmark for unstable bladder contractions is hyperexcitability and changes in the nature of spontaneous phasic activity of the bladder smooth muscle. In this study, we have characterized the spontaneous activity of the urinary bladder smooth muscle from the pig, a widely used model for studying human bladder function.
Our studies demonstrate that phasic activity of the pig detrusor is myogenic and is influenced by the presence of urothelium. Denuded strips exhibit robust spontaneous activity measured as mean area under the contraction curve (AUC=188.9±15.63 mNs) compared to intact strips (AUC=7.3±1.94 mNs).
Spontaneous phasic activity, particularly the amplitude, is dependent on both calcium entry through voltage‐dependent calcium channels and release from ryanodine receptors as shown by inhibition of spontaneous activity by nifedipine and ryanodine respectively.
Inhibition of BKCa channels by iberiotoxin (100 nM) resulted in an increase in contraction amplitude (89.1±20.4%) and frequency (92.5±31.0%). The SKCa channel blocker apamin (100 nM) also increased contraction amplitude (69.1±24.3%) and frequency (53.5±13.6%) demonstrating that these mechanisms are critical to the regulation of phasic spontaneous activity.
Inhibition of KATP channels by glyburide (10 μM) did not significantly alter myogenic contractions (AUC=18.5±12.3%). However, KATP channel openers (KCOs) showed an exquisite sensitivity for suppression of spontaneous myogenic activity. KCOs were generally 15 fold more potent in suppressing spontaneous activity compared to contractions evoked by electrical field‐stimulation. These studies suggest that potassium channel modulation, particularly KATP channels, may offer a unique mechanism for controlling spontaneous myogenic activity especially those associated with the hyperexcitability occurring in unstable bladders.

British Journal of Pharmacology (2002) 135, 639–648; doi:10.1038/sj.bjp.0704499
Alterations in phenylephrine‐induced contractions and the vascular expression of Na+,K+‐ATPase in ouabain‐induced hypertension
Authors: Rossoni Luciana V , Salaices Mercedes , Marín Jesús , Vassallo Dalton V , Alonso María J 
Published: January 2005

Hypertension development, phenylephrine‐induced contraction and Na+,K+‐ATPase functional activity and protein expression in aorta (AO), tail (TA) and superior mesenteric (SMA) arteries from ouabain‐ (25 μg day−1, s.c., 5 weeks) and vehicle‐treated rats were evaluated.
Ouabain treatment increased systolic blood pressure (127±1 vs 160±2 mmHg, n=24, 35; P<0.001) while the maximum response to phenylephrine was reduced (P<0.01) in AO (102.8±3.9 vs 67.1±10.1% of KCl response, n=12, 9) and SMA (82.5±7.5 vs 52.2±5.8%, n=12, 9).
Endothelium removal potentiated the phenylephrine response to a greater extent in segments from ouabain‐treated rats. Thus, differences of area under the concentration‐response curves (dAUC) in endothelium‐denuded and intact segments for control and ouabain‐treated rats were, respectively: AO, 56.6±9.6 vs 198.3±18.3 (n=9, 7); SMA, 85.5±15.4 vs 165.4±24.8 (n=6, 6); TA, 13.0±6.1 vs 39.5±10.4% of the corresponding control AUC (n=6, 6); P<0.05.
The relaxation to KCl (1 – 10 mM) was similar in segments from both groups. Compared to controls, the inhibition of 0.1 mM ouabain on KCl relaxation was greater in AO (dAUC: 64.8±4.6 vs 84.0±5.1%, n=11, 14; P<0.05), similar in SMA (dAUC: 39.1±3.9 vs 43.3±7.8%, n=6, 7; P>0.05) and smaller in TA (dAUC: 62.1±5.5 vs 41.4±8.2%, n=12, 13; P<0.05) in ouabain‐treated rats.
Protein expression of both α1 and α2 isoforms of Na+,K+‐ATPase was augmented in AO, unmodified in SMA and reduced in TA from ouabain‐treated rats.
These results suggest that chronic administration of ouabain induces hypertension and regional vascular alterations, the latter possibly as a consequence of the hypertension.

British Journal of Pharmacology (2002) 135, 771–781; doi:10.1038/sj.bjp.0704501
The effect of 3,4‐methylenedioxymethamphetamine (MDMA, ?ecstasy?) and its metabolites on neurohypophysial hormone release from the isolated rat hypothalamus
Authors: Forsling Mary L , Fallon John K , Shah Darshna , Tilbrook Gary S , Cowan David A , Kicman Andrew T , Hutt Andrew J 
Published: January 2005

Methylenedioxymethamphetamine (MDMA, “ecstasy”), widely used as a recreational drug, can produce hyponatraemia. The possibility that this could result from stimulation of vasopressin by MDMA or one of its metabolites has been investigated in vitro.
Release of both oxytocin and vasopressin from isolated hypothalami obtained from male Wistar rats was determined under basal conditions and following potassium (40 mM) stimulation. The results were compared with those obtained for basal and stimulated release in the presence of MDMA or metabolites in the dose range 1 μM to 100 pM (n=5 – 8) using Student's t‐test with Dunnett's correction for multiple comparisons.
All compounds tested affected neurohypophysial hormone release, HMMA (4‐hydroxy‐3‐methoxymethamphetamine) and DHA (3,4‐dihydroxyamphetamine) being more active than MDMA, and DHMA (3,4‐dihydroxymethamphetamine) being the least active. The effect on vasopressin release was greater than that on oxytocin. In the presence of HMMA the ratio test:control for basal release increased for vasopressin from 1.1±0.16 to 2.7±0.44 (s.e.m., P<0.05) at 10 nM and for oxytocin from 1.0±0.05 to 1.6±0.12 in the same hypothalami. For MDMA the ratio increased to 1.5±0.27 for vasopressin and to 1.28±0.04 for oxytocin for 10 nM.
MDMA and its metabolites can stimulate both oxytocin and vasopressin release in vitro, the response being dose dependent for each drug with HMMA being the most potent.

British Journal of Pharmacology (2002) 135, 649–656; doi:10.1038/sj.bjp.0704502
The effects of heparin and related molecules on vascular permeability and neutrophil accumulation in rabbit skin
Authors: Jones Helen , Paul William , Page Clive P 
Published: January 2005

Unfractionated heparin (UH) has been shown to possess a wide range of properties which are potentially anti‐inflammatory. Many of these studies, including effects of heparin on adhesion of inflammatory cells to endothelium, have been carried out in vitro. In the present study, we have used radioisotopic techniques to study the effect of UH, and related molecules, on in vivo inflammatory responses (plasma exudation (PE) and PMN accumulation) in rabbit skin induced by cationic proteins, mediators and antigen.
Intradermal (i.d.) pretreatment with UH dose‐dependently inhibited poly‐L‐lysine (PLL)‐induced responses. The same treatment had no effect on antigen (extract of Alternaria tenuis, AT)‐, formyl‐methionyl‐leucyl‐phenylalanine (fMLP)‐ or leukotriene (LT) B4‐induced responses, although i.d. dextran sulphate (DS) significantly inhibited responses to all of these mediators.
High dose (10,000 u kg−1) intravenous UH significantly decreased cutaneous responses to fMLP and LTB4. By comparison, the selectin inhibitor, fucoidin, and DS, were very effective inhibitors of these responses, and of responses to AT and PLL.
In contrast to the weak effect in the in vivo studies, UH significantly inhibited in vitro homotypic aggregation of rabbit PMNs, showing that it can modify PMN function.
Our data with i.d. UH confirm the important ability of this molecule to interact with and neutralize polycationic peptides in vivo, suggesting that this is a prime role of endogenous heparin. The lack of effect of exogenous heparin on acute inflammatory responses induced by allergen, suggests that cationic proteins are unlikely to be primary mediators of the allergen‐induced PE or PMN accumulation.

British Journal of Pharmacology (2002) 135, 469–479; doi:10.1038/sj.bjp.0704505
Effects of chronic drug treatments on increases in intracellular calcium mediated by nicotinic acetylcholine receptors in SH‐SY5Y cells
Authors: Ridley Diana L , Pakkanen Jukka , Wonnacott Susan 
Published: January 2005

SH‐SY5Y cells express α7 and α3* subtypes of nicotinic acetylcholine receptors (AChR). Numbers of these receptors are upregulated by chronic treatment with nicotinic agonists or KCl. In this study we have examined the functional consequences of these drug treatments on nicotine‐ or KCl‐evoked increases in [Ca2+]i, in SH‐SY5Y cells.
In untreated cells, nicotine increased [Ca2+]i (EC50 7.5 μM). Responses to 10 μM nicotine were abolished by the non‐selective nicotinic antagonist mecamylamine and were partially blocked by α7‐selective antagonists, the α3β2*‐selective antagonist α‐conotoxin‐MII, and by cadmium and verapamil.
After treatment for 4 days with nicotinic agonists, nicotine‐evoked increases in [Ca2+]i were significantly decreased by about 25%. Nicotine‐evoked responses were paradoxically increased in the presence of acute methyllycaconitine (MLA; an α7‐selective antagonist) although other α7‐selective antagonists were without effect, while α‐conotoxin‐MII gave a partial inhibition. The increase observed with MLA was abolished by mecamylamine but not by α‐conotoxin‐MII and was still observed 24 h after chronic nicotine treatment.
After treatment for 4 days with KCl, nicotine‐evoked increases in [Ca2+]i were also decreased by 25%, but acute MLA was without effect. Responses to 20 mM KCl were unchanged by prior treatment with nicotine or KCl. Treatment for 4 days with 5 μM verapamil reduced responses to both nicotine and KCl by about 50%.
Multiple nicotinic AChR subtypes contribute to nicotine‐evoked increases in [Ca2+]i in SH‐SY5Y cells. Responses to acute nicotine are reduced after chronic nicotine or KCl treatment, with loss of the component attributed to the α7 subtype. However, in nicotine‐treated cells this effect is reversed when nicotine stimulation is applied in the presence of acute MLA. The antagonist may assist in converting a non‐functional α7 nicotinic AChR to a conducting state.

British Journal of Pharmacology (2002) 135, 1051–1059; doi:10.1038/sj.bjp.0704508