bluuebunny/crossref_metadata_2025_split huggingface dataset:
Parathyroid hormone increases the sensitivity of inositol trisphosphate receptors by a mechanism that is independent of cyclic AMP
Authors: Tovey Stephen C , Goraya Tasmina A , Taylor Colin W 
Published: January 2003

In fura 2‐loaded HEK‐293 cells stably expressing human type 1 parathyroid hormone (PTH) receptors, PTH potentiated the Ca2+ mobilization evoked by carbachol by >4 fold without itself increasing the intracellular [Ca2+].
PTH potentiated the Ca2+ release evoked by a cell‐permeant analogue of inositol 1,4,5‐trisphosphate (InsP3BM).
Prolonged incubation with InsP3BM emptied the Ca2+ stores as effectively as PTH in combination with a maximal concentration of carbachol, indicating that PTH did not increase the size of the InsP3‐sensitive Ca2+ pool.
Responses to PTH were unaffected by disruption of the cytoskeleton.
The EC50 for carbachol‐evoked Ca2+ release and InsP3 formation were indistinguishable (∼40 μM), consistent with even the highest concentrations of carbachol generating insufficient InsP3 to release the entire InsP3‐sensitive Ca2+ pool.
Inhibition of cyclic AMP‐dependent protein kinase A (PKA), using H89 or CMIQ, did not affect potentiation of carbachol‐evoked Ca2+ signals by PTH.
SQ22536 or DDA, inhibitors of adenylyl cyclase, inhibited PTH‐evoked cyclic AMP formation and IBMX, an inhibitor of cyclic nucleotide phosphodiesterase, increased the amount of cyclic AMP detected after stimulation by PTH. None of these drugs affected the potentiation of Ca2+ signals by maximal or submaximal concentrations of PTH.
We conclude that PTH potentiates the Ca2+ release evoked by receptors that stimulate InsP3 formation by sensitizing InsP3 receptors through a cyclic AMP‐independent mechanism.

British Journal of Pharmacology (2003) 138, 81–90. doi:10.1038/sj.bjp.0705011
α2 Adrenoceptor‐mediated vasoconstriction in porcine palmar lateral vein: role of phosphatidylinositol 3‐kinase and EGF receptor transactivation
Authors: Roberts R E 
Published: January 2003

α2 Adrenoceptors cause vasoconstriction in the porcine palmar lateral vein through a mechanism involving the ERK signal transduction cascade, calcium influx, and a Src tyrosine kinase. The aim of the present study was to determine if phosphatidylinositol 3‐kinase (PI 3‐kinase) and/or epidermal growth factor (EGF) receptor transactivation are also involved.
α2 Adrenoceptor‐mediated vasoconstriction and ERK2 activation in the porcine palmar lateral vein was inhibited in the presence of either the PI 3‐kinase inhibitor LY294002, or the EGF receptor tyrosine kinase inhibitor AG1478 suggesting the involvement of both PI 3‐kinase and EGF receptor transactivation.
Akt phosphorylation was increased in segments of porcine palmar lateral vein contracted with UK14304 indicating an increase in Akt activation. This is a further indication that PI 3‐kinase is involved in α2 adrenoceptor‐mediated vasoconstriction. Akt activation was inhibited by the Src tyrosine kinase inhibitor PP2, and removal of extracellular calcium.
UK14304 (10 μM) stimulated an increase in intracellular calcium in segments of palmar lateral vein. This was inhibited by removal of extracellular calcium, but not by nifedipine suggesting the rise in calcium is due to influx of calcium through non‐L type calcium channels. The increase in calcium was also inhibited by LY294002 indicating that PI 3‐kinase is upstream of calcium influx.
These data indicate that α2 adrenoceptor‐mediated vasoconstriction in the porcine palmar lateral vein is dependent upon stimulation of PI 3‐kinase, leading to an influx of calcium. This results in activation of the EGF receptor tyrosine kinase, and finally activation of ERK–MAP kinase.

British Journal of Pharmacology (2003) 138, 107–116. doi:10.1038/sj.bjp.0705014
Effector mechanism of magnolol‐induced apoptosis in human lung squamous carcinoma CH27 cells
Authors: Yang Shu‐Er , Hsieh Ming‐Tsuen , Tsai Tung‐Hu , Hsu Shih‐Lan 
Published: January 2003

Magnolol, an active component isolated from the root and stem bark of Magnolia officinalis, has been reported to exhibit antitumour effects, but little is known about its molecular mechanisms of action.
Magnolol inhibited proliferation of human lung squamous carcinoma CH27 cells at low concentrations (10–40 μM), and induced apoptosis at high concentrations (80–100 μM).
Treatment with 80 μM magnolol significantly increased the expression of Bad and Bcl‐XS proteins, whereas it decreased the expression of Bcl‐XL. Overexpression of Bcl‐2 protected CH27 cells against magnolol‐triggered apoptosis.
Magnolol treatment resulted in accumulation of cytosolic cytochrome c and activation of caspase‐9 and downstream caspases (caspase‐3 and ‐6). Pretreatment with z‐VAD‐fmk markedly inhibited magnolol‐induced cell death, but did not prevent cytosolic cytochrome c accumulation.
Magnolol induced a modest and persistent JNK activation and ERK inactivation in CH27 cells without evident changes in the protein levels. The responsiveness of JNK and ERK to magnolol suggests the involvement of these kinases in the initiation of the apoptosis process.
These results indicate that regulation of the Bcl‐2 family, accumulation of cytosolic cytochrome c, and activation of caspase‐9 and caspase‐3 may be the effector mechanisms of magnolol‐induced apoptosis.

British Journal of Pharmacology (2003) 138, 193–201. doi:10.1038/sj.bjp.0705024
Pharmacological characterization of 5‐HT1B receptor‐mediated inhibition of local excitatory synaptic transmission in the CA1 region of rat hippocampus
Authors: Mlinar Boris , Falsini Chiara , Corradetti Renato 
Published: January 2003

In the hippocampus, axon collaterals of CA1 pyramidal cells project locally onto neighbouring CA1 pyramidal cells and interneurones, forming a local excitatory network which, in disinhibited conditions, feeds polysynaptic epscs (poly‐epscs). 5‐hydroxytryptamine (5‐HT) has been shown to inhibit poly‐epscs through activation of a presynaptic receptor. The aim of the present work was the pharmacological characterization of the 5‐HT receptor involved in this 5‐HT action.
Poly‐epscs, evoked by electrical stimulation of the stratum radiatum and recorded in whole‐cell voltage‐clamp from CA1 pyramidal neurones, were studied in mini‐slices of the CA1 region under pharmacological block of GABAA, GABAB, and 5‐HT1A receptors.
The 5‐HT1B receptor selective agonist 1,4‐dihydro‐3‐(1,2,3,6‐tetrahydro‐4‐pyridinyl)‐5H‐pyrrolo[3,2‐b]pyridin‐5‐one dihydrochloride (CP 93129) inhibited poly‐epscs (EC50=55 nM), an effect mimicked by the 5‐HT1B ligands 5‐carboxamidotryptamine (5‐CT; EC50=14 nM) and methylergometrine (EC50=78 nM), but not by 1‐(3‐chlorophenyl)piperazine dihydrochloride (mCPP; 10 μM) or 7‐trifluoromethyl‐4(4‐methyl‐1‐piperazinyl)‐pyrrolo[1,2‐a]quinoxaline dimaleate (CGS 12066B; 10 μM).
The effects of CP 93129 and 5‐CT were blocked by the selective 5‐HT1B receptor antagonist 3‐[3‐(dimethylamino)propyl]‐4‐hydroxy‐N‐[4‐(4‐pyridinyl)phenyl]benzamide dihydrochloride (GR 55562; KB∼100 nM) and by cyanopindolol (KB=6 nM); methiothepin (10 μM) and dihydroergotamine (1 μM). For both GR 55562 and methiothepin, application times of at least two hours were required in order to achieve their full antagonistic effects.
Our results demonstrate that 5‐HT1B receptors are responsible for the presynaptic inhibition of neurotransmission at CA1/CA1 local excitatory synapses exerted by 5‐HT.

British Journal of Pharmacology (2003) 138, 71–80. doi:10.1038/sj.bjp.0705026
Comparison of signalling mechanisms involved in rat mesenteric microvessel contraction by noradrenaline and sphingosylphosphorylcholine
Authors: Altmann Christoph , Steenpaß Veronika , Czyborra Peter , Hein Peter , Michel Martin C 
Published: January 2003

We have compared the signalling mechanisms involved in the pertussis toxin‐sensitive and ‐insensitive contraction of rat isolated mesenteric microvessels elicited by sphingosylphosphorylcholine (SPC) and noradrenaline (NA), respectively.
The phospholipase D inhibitor butan‐1‐ol (0.3%), the store‐operated Ca2+ channel inhibitor SK>F 96,365 (10 μM), the tyrosine kinase inhibitor genistein (10 μM), and the src inhibitor PP2 (10 μM) as well as the negative controls (0.3% butan‐2‐ol and 10 μM diadzein and PP3) had only little effect against either agonist.
Inhibitors of phosphatidylinositol‐3‐kinase (wortmannin and LY 294,002, 10 μM each) or of mitogen‐activated protein kinase kinase (PD 98,059 and U 126, 10 μM each) did not consistently attenuate NA‐ and SPC‐induced contraction as compared to their vehicles or negative controls (LY 303,511 or U 124).
The phospholipase C inhibitor U 73,122 (10 μM) markedly inhibited the SPC‐ and NA‐induced contraction (70% and 88% inhibition of the response to the highest NA and SPC concentration, respectively), whereas its negative control U 73,343 (10 μM) caused only less than 30% inhibition.
The rho‐kinase inhibitors Y 27,632 (10 μM) and fasudil (30 μM) caused a rightward‐shift of the NA concentration‐response curve by 0.7–0.8 log units and reduced the response to 10 μM SPC by 88% and 83%, respectively.
These data suggest that SPC and NA, while acting on different receptors coupling to different G‐protein classes, elicit contraction of rat mesenteric microvessels by similar signalling pathways including phospholipase C and rho‐kinase.

British Journal of Pharmacology (2003) 138, 261–271. doi:10.1038/sj.bjp.0705028
Tachykinin NK3 and NK1 receptor activation elicits secretion from porcine airway submucosal glands
Authors: Phillips Jonathan E , Hey John A , Corboz Michel R 
Published: January 2003

We presently characterized the tachykinin receptor subtypes, using tachykinin receptor agonists and selective antagonists, that induce submucosal gland fluid flux (JG) from porcine tracheal explants with the hillocks technique. We also investigated the effects of the tachykinin receptor agonists on the electrophysiologic parameters of the tracheal epithelium in Ussing chambers.
The NK1 tachykinin receptor agonist substance P (SP, 1 μM) and the NK3 tachykinin receptor agonist [MePhe7]neurokinin B ([MePhe7]NKB, 1 μM) induced gland fluid fluxes of 0.29±0.03 μl min−1 cm−2 (n=26) and 0.36±0.05 μl min−1 cm−2 (n=24), respectively; while the NK2 tachykinin receptor agonist [βAla8]neurokinin A (4‐10) ([βAla8]NKA (4‐10), 1 μM) had no effect on JG (n=10).
The NK1 receptor antagonist CP99994 (1 μM, n=9) blocked 93% of the SP‐induced JG, whereas the NK3 receptor antagonist SB223412 (1 μM, n=12) had no effect on the SP‐induced JG. However, SB223412 (1 μM, n=9) blocked 89% of the [MePhe7]NKB‐induced JG while CP99994 (1 μM, n=10) did not affect the [MePhe7]NKB‐induced JG. The NK2 receptor antagonist SR48968 (1 μM) did not block the JG induced by either the NK1 (n=4) or NK3 (n=13) receptor agonists.
The nicotinic ganglionic acetylcholine receptor antagonist hexamethonium (1 μM) and the muscarinic acetylcholine receptor antagonist atropine (1 μM) also decreased the NK3 receptor agonist‐induced JG by 67% (n=10) and 71% (n=12), respectively.
The potential difference (PD), short‐circuit current (ISC), and membrane resistance (RM) of the porcine tracheal epithelial membranes were not significantly affected by any of the neurokinin agonists or antagonists (1 μM, basolateral) used in this study, although SP and [βAla8]NKA (4‐10) induced a slight transient epithelial hyperpolarization.
These data suggest that NK1 and NK3 receptors induce porcine airway gland secretion by different mechanisms and that the NK3 receptor agonists induced secretion is likely due to activation of prejunctional NK3 receptors on parasympathetic nerves, resulting in acetylcholine‐release. We conclude that tachykinin receptor antagonists may have therapeutic potential in diseases with pathophysiological mucus hypersecretion such as asthma and chronic bronchitis.

British Journal of Pharmacology (2003) 138, 254–260. doi:10.1038/sj.bjp.0705029
Monovalent cation (MC) current in cardiac and smooth muscle cells: regulation by intracellular Mg2+ and inhibition by polycations
Authors: Zakharov Sergey I , Smani Tarik , Leno Endri , Macianskiene Regina , Mubagwa Kanigula , Bolotina Victoria M 
Published: January 2003

Previously we have described a monovalent cation (MC) current that could be unmasked by the removal of extracellular divalent cations in vascular smooth muscle cells (SMC) and cardiac myocytes, but specific and potent inhibitors of MC current have not been found, and the mechanism of its intracellular regulation remains obscure.
Here we show that small MC current is present in intact cells and could be dramatically up‐regulated during cell dialysis. MC current in dialyzed cells strongly resembled monovalent cation current attributed to Ca2+ release‐activated Ca2+‐selective (CRAC) channels, but its activation did not require depletion of Ca2+ stores, and was observed when the cells were dialyzed with, or without BAPTA.
Intracellular free Mg2+ inhibits MC current with Kd=250 μM.
Extracellular (but not intracellular) spermine effectively blocked MC current with Kd =3–10 μM, while store‐operated cations (SOC) channels and capacitative Ca2+ influx were not affected.
Spermine effectively inhibited MC current‐induced SMC depolarization, and prevented Ca2+ paradox‐induced vascular contracture.
Both, MC and SOC currents were inhibited by 2‐aminoethoxydiphenyl borate (2‐APB).
It is concluded that MC current could be regulated by intracellular Mg2+, and low concentrations of extracellular spermine could be used to discriminate it from SOC current, and to assess its role in cellular function.

British Journal of Pharmacology (2003) 138, 234–244. doi:10.1038/sj.bjp.0705074
Evaluation of cytochrome P4502C9 metabolic activity with tolbutamide in CYP2C9*1 heterozygotes
Authors: Lee Craig R. , Pieper John A. , Hinderliter Alan L. , Blaisdell Joyce A. , Goldstein Joyce A. 
Published: January 2003

ObjectivesMultiple single‐nucleotide polymorphisms in the gene encoding cytochrome P450 (CYP) 2C9 have been identified, but the functional significance of the various putative defective genotypes in humans merits further study.MethodsUsing tolbutamide as a probe of CYP2C9 activity, we evaluated CYP2C9 phenotype in 15 healthy individuals expressing the CYP2C9*1/*1, *1/*2, and *1/*3 genotypes (n = 5 per group). CYP2C9 genotype was determined by polymerase chain reaction‐restriction fragment length polymorphism methods. Subjects received 500 mg of tolbutamide, with plasma and urine collected over a 24‐hour period. Plasma tolbutamide and urinary tolbutamide, 4′‐hydroxytolbutamide, and carboxytolbutamide concentrations were determined by an HPLC method.ResultsTolbutamide area under the plasma concentration‐time curve from time zero to infinity [AUC(0‐∞)] significantly increased by 1.5‐fold and 1.9‐fold, respectively, in subjects expressing the CYP2C9*1/*2 and *1/*3 genotypes compared with *1/*1 subjects. Statistically significant reductions in tolbutamide oral clearance (29% and 48%) and formation clearance (38% and 56%) were detected in the *1/*2 and *1/*3 individuals, respectively, compared with *1/*1 subjects. The increases in AUC(0‐∞) and decreases in oral clearance observed in the *1/*3 individuals were also significantly greater than those expressing the *1/*2 genotype (P < .05). The amount of urinary 4′‐hydroxytolbutamide and carboxytolbutamide excreted in the 0‐ to 12‐hour and 6‐ to 12‐hour collection intervals was significantly less in *1/*2 and *1/*3 individuals compared with *1/*1 subjects. With tolbutamide used as a CYP2C9 probe, CYP2C9 genotype was the major determinant of CYP2C9 phenotype (r2 = 0.77)ConclusionsCYP2C9 activity was significantly reduced in *1 heterozygotes compared with *1 homozygotes, and metabolism was more severely impaired in *1/*3 individuals compared with those expressing *1/*2.Clinical Pharmacology & Therapeutics (2002) 72, 562–571; doi: 10.1067/mcp.2002.127913
Nimodipine: Drug pharmacokinetics and plasma adenosine levels in patients affected by cerebral ischemia
Authors: Blardi Patrizia , Urso Renato , de Lalla Arianna , Volpi Luciana , Perri Tullio Di , Auteri Alberto 
Published: January 2003

Background and ObjectiveNimodipine is a dihydropyridine calcium channel blocker used in the treatment of ischemic damage in subarachnoid hemorrhage. Recent investigations have shown that it is able to inhibit adenosine transport in human red blood cells and parietal cortex neurons. In this study we investigated the pharmacokinetics of nimodipine and the effect on plasma adenosine levels in patients affected by cerebral ischemia.MethodsTwelve patients with cerebral ischemia (9 men and 3 women; mean age, 68.8 ± 11.2 years; mean weight, 67.9 ± 9.3 kg) were admitted to the study. They received nimodipine intravenously (a bolus of 0.03 mg/kg) and orally (single doses of 30, 60, and 90 mg) during different sessions. Blood samples for adenosine and nimodipine were collected at fixed intervals up to 480 minutes. Adenosine and nimodipine plasma levels were detected by HPLC methods.ResultsBoth the intravenous and oral administrations induced a statistically significant increase in plasma adenosine levels (P < .001), which appeared to be related to the dose and route of drug administration. In particular, a 67.8% increase was observed after intravenous administration, and increases of 28.9%, 43.6%, and 60.2% were observed after 30 mg, 60 mg, and 90 mg of nimodipine, respectively. The pharmacokinetic parameters of nimodipine after intravenous administration were as follows: peak concentration (Cmax), 319.6 ± 38.9 ng/mL at the first sampling time; area under the curve (AUC), 239 ± 25 ng · h/mL; and terminal half‐life, 3.12 ± 0.97 hours. After oral administration, the drug kinetics was linear in the administered dose range and the pharmacokinetic parameters were as follows: Cmax(30 mg), 46.1 ± 5.8 ng/mL; Cmax(60 mg), 81.7 ± 14.6 ng/mL; Cmax(90 mg), 131.6 ± 16.3 ng/mL; AUC(30 mg), 119 ± 25 ng · h/mL; AUC(60 mg), 256 ± 48 ng · h/mL; and AUC(90 mg), 389 ± 54 ng · h/mL. The half‐life was similar to the values observed after intravenous administration, whereas the bioavailability ranged between 2% and 5.9%.ConclusionsOur data indicate that the administration of nimodipine induces an increase in plasma adenosine levels, and we hypothesize that the drug activity could be associated, at least partially, with adenosine mediation.Clinical Pharmacology & Therapeutics (2002) 72, 556–561; doi: 10.1067/mcp.2002.128127
Pharmacokinetics and pharmacodynamics of darbepoetin alfa and epoetin in patients undergoing dialysis*
Authors: Allon Michael , Kleinman Kenneth , Walczyk Michael , Kaupke Charles , Messer‐Mann Louise , Olson Kurt , Heatherington Anne C. , Maroni Bradley J. 
Published: January 2003

ObjectiveThe aim of this multicenter, randomized, open‐label study was to compare the pharmacokinetic and pharmacodynamic profiles of darbepoetin alfa, a new erythropoiesis‐stimulating protein, and recombinant human erythropoietin (epoetin) after repeated intravenous dosing in patients with chronic kidney disease receiving hemodialysis.MethodsForty‐seven patients were randomized to receive darbepoetin alfa administered once weekly (n = 17) or 3 times weekly (n = 15) or epoetin administered 3 times weekly (n = 15) for up to 52 weeks. Pharmacokinetic profiles were measured during weeks 1 and 12 and at hemoglobin steady state (defined as a hemoglobin concentration within the target range for 4 consecutive weeks after week 12 with no change in study drug dose) or between weeks 36 and 40, whichever occurred first.ResultsAt each of the 3 time points evaluated, the terminal half‐life of darbepoetin alfa was 2 to 3 times longer and the clearance approximately 4 times slower than those of epoetin. At week 12, the terminal half‐life was 23.4 hours with darbepoetin alfa once weekly, 18.3 hours with darbepoetin alfa 3 times weekly, and 8.0 hours with epoetin 3 times weekly. The pharmacokinetics of darbepoetin alfa was not dependent on dose or time. Mean hemoglobin values at steady state were all approximately 11 g/dL, within the target range of 9.0 to 13.0 g/dL. Safety analyses revealed no differences between darbepoetin alfa and epoetin.ConclusionsThe pharmacokinetic and pharmacodynamic profiles and safety data for darbepoetin alfa demonstrate that it can be administered less frequently than epoetin in patients with chronic kidney disease receiving hemodialysis, thus simplifying anemia management.Clinical Pharmacology & Therapeutics (2002) 72, 546–555; doi: 10.1067/mcp.2002.128374
Disposition of nasal, intravenous, and oral methadone in healthy volunteers
Authors: Dale Ola , Hoffer Christine , Sheffels Pamela , Kharasch Evan D. 
Published: January 2003

ObjectiveNasal administration of many opioids demonstrates rapid uptake and fast onset of action. Nasal administration may be an alternative to intravenous and oral administration of methadone and was therefore studied in human volunteers.MethodsThe study was approved by the Institutional Review Board of the University of Washington, Seattle. Eight healthy volunteers (6 men and 2 women) aged 19 to 33 years were enrolled after informed written consent was obtained. Subjects received 10 mg methadone hydrochloride nasally, orally, or intravenously on 3 separate occasions in a crossover design. Nasal methadone (50 mg/mL in aqueous solution) was given as a 100‐μL spray in each nostril (Pfeiffer BiDose sprayer). Blood samples for liquid chromatography‐mass spectrometry analyses of methadone and the metabolite 2‐ethyl‐1,5‐dimethyl‐3,3‐diphenylpyrrolinium were drawn for up to 96 hours. The methadone effect was measured by noninvasive infrared pupilometry coincident with blood sampling.ResultsNasal uptake of methadone was rapid, with maximum plasma concentrations occurring within 7 minutes. The maximum effects of intravenous, nasal, and oral methadone, on the basis of dark‐adapted pupil diameter, were reached in about 15 minutes, 30 minutes, and 2 hours, respectively. The respective durations were 24, 10, and 8 hours. Both nasal and oral bioavailabilities were 0.85. Subjects reported that nasal methadone caused a burning sensation.ConclusionsNasal administration of methadone results in rapid absorption and onset of effect and high bioavailability, which was greater than that reported for other nasal opioids, with a similar duration of effect. Nasal administration may be an alternative route of methadone administration; however, improved formulations are desirable to reduce nasal irritation.Clinical Pharmacology & Therapeutics (2002) 72, 536–545; doi: 10.1067/mcp.2002.128386