bluuebunny/crossref_metadata_2025_split huggingface dataset:
Properties of the Na+/K+ pump current in small neurons from adult rat dorsal root ganglia
Authors: Hamada Kanako , Matsuura Hiroshi , Sanada Mitsuru , Toyoda Futoshi , Omatsu‐Kanbe Mariko , Kashiwagi Atsunori , Yasuda Hitoshi 
Published: April 2003

The present investigation was undertaken to characterize the Na+/K+ pump current in small (25 μm in soma diameter) dorsal root ganglion (DRG) neurons isolated from lumbar L4‐6 segments of adult rats.
The Na+/K+ pump current was identified as an ouabain‐sensitive current during square voltage steps to membrane potentials between +40 and −120 mV, using the whole‐cell patch‐clamp technique in which Ca2+ and K+ channel currents and Na+/Ca2+ exchange currents were minimized. The Na+/K+ pump current was practically time‐independent over the entire voltage range examined and exhibited a voltage‐dependence; its current – voltage (I–V) relationship displayed a positive slope at potentials between −120 and 0 mV but nearly plateau levels at positive membrane potentials.
The concentration‐dependent block of Na+/K+ pump current (activated by 30 mM pipette Na+) by ouabain at concentrations between 0.1 μM and 5 mM was biphasic and was well described using a two‐binding site model with dissociation constants for high‐ and low‐affinity binding sites of 0.20 and 140.1 μM, respectively. The relative amplitude of the Na+/K+ pump current produced by low‐ and high‐affinity sites (probably α1β1 and α3β1 isozymes, respectively) was estimated to be 13 : 1 in the presence of 30 mM Na+ in the pipette solution.
Additionally, the activation of Na+/K+ pump current by pipette Na+ at concentrations ranging from 5 to 100 mM also exhibited a biphasic concentration dependence which can be reasonably well fitted by assuming the existence of two isozymes having high and low affinities for Na+ (6.7 and 67.6 mM, respectively).
Thus, the present investigation provides functional evidence to suggest that the Na+/K+ ATPase comprises two functionally distinct isozymes as expected for α1β1 and α3β1 in rat small DRG neurons.

British Journal of Pharmacology (2003) 138, 1517–1527. doi:10.1038/sj.bjp.0705170
Growth hormone protects human lymphocytes from irradiation‐induced cell death
Authors: Lempereur Laurence , Brambilla Daria , Maria Scoto Giovanna , D'Alcamo Maria , Goffin Vincent , Crosta Lucia , Palmucci Tullio , Rampello Liborio , Bernardini Renato , Cantarella Giuseppina 
Published: April 2003

Undesired effects of cancer radiotherapy mainly affect the hematopoietic system. Growth hormone (GH) participates in both hematopoiesis and modulation of the immune response. We report both r‐hGH cell death prevention and restoration of secretory capacities of irradiated human peripheral blood lymphocytes (PBL) in vitro.
r‐hGH induced cell survival and increased proliferation of irradiated cells. Western blot analysis indicated that these effects of GH were paralleled by increased expression of the antiapoptotic protein Bcl‐2.
r‐hGH restored mitogen‐stimulated release of IL‐2 by PBL. Preincubation of irradiated lymphocytes with the growth hormone receptor (GHR) antagonists B2036 and G120 K abrogated r‐hGH‐dependent IL‐2 release.
These results demonstrate that r‐hGH protects irradiated PBL from death in a specific, receptor‐mediated manner. Such effect of r‐hGH on PBL involves activation of the antiapoptotic gene bcl‐2 and prevention of cell death, associated with preserved functional cell capacity. Finally, potential use of GH as an immunopotentiating agent could be envisioned during radiation therapy of cancer.

British Journal of Pharmacology (2003) 138, 1411–1416. doi:10.1038/sj.bjp.0705173
Extracellular ATP‐induced calcium channel inhibition mediated by P1/P2Y purinoceptors in hamster submandibular ganglion neurons
Authors: Abe Mitsuhiro , Endoh Takayuki , Suzuki Takashi 
Published: April 2003

The presence and profile of purinoceptors in neurons of the hamster submandibular ganglion (SMG) have been studied using the whole‐cell configuration of the patch‐clamp technique.
Extracellular application of adenosine 5′‐triphosphate (ATP) reversibly inhibited voltage‐dependent Ca2+ channel (VDCC) currents (ICa) via Gi/o‐protein in a voltage‐dependent manner.
Extracellular application of uridine 5′‐triphosphate (UTP), 2‐methylthioATP (2‐MeSATP), α,β‐methylene ATP (α,β‐MeATP) and adenosine 5′‐diphosphate (ADP) also inhibited ICa. The rank order of potency was ATP=UTP>ADP>2‐MeSATP=α,β‐MeATP.
The P2 purinoceptor antagonists, suramin and pyridoxal‐5‐phosphate‐6‐azophenyl‐2′, 4′‐disulfonic acid (PPADS), partially antagonized the ATP‐induced inhibition of ICa, while coapplication of suramin and the P1 purinoceptor antagonist, 8‐cyclopentyl‐1,3‐dipropylxanthine (DPCPX), virtually abolished ICa inhibition. DPCPX alone partially antagonized ICa inhibition.
Suramin antagonized the UTP‐induced inhibition of ICa, while DPCPX had no effect.
Extracellular application of adenosine (ADO) also inhibited ICa in a voltage‐dependent manner via Gi/o‐protein activation.
Mainly N‐ and P/Q‐type VDCCs were inhibited by both ATP and ADO via Gi/o‐protein βγ subunits in seemingly convergence pathways.

British Journal of Pharmacology (2003) 138, 1535–1543. doi:10.1038/sj.bjp.0705174
Ethanol tachyphylaxis in spinal cord motorneurons: role of metabotropic glutamate receptors
Authors: Li Hui‐Fang , Wang Meng‐Ya , Knape Jessica , Kendig Joan J 
Published: April 2003

Ethanol (EtOH) tachyphylaxis (acute tolerance), a time‐dependent decrease in apparent potency, is known in vivo and in some neuronal preparations. The present studies characterize EtOH tachyphylaxis in spinal motorneurons and test the hypothesis that metabotropic glutamate receptors (mGluRs) play a role.
Patch clamp studies were carried out in motorneurons in rat spinal cord slices. Currents were evoked by pulses of glutamate, alpha‐amino‐3‐hydroxy‐5‐methylisoxazole‐4‐propionic acid (AMPA) or N‐methyl‐D‐aspartic acid (NMDA).
In nine of 15 cells, ethanol depression of glutamate‐evoked currents was time‐dependent. EtOH depressed current area 36.9±3% at 8–10 min, but only 16.8±3% at 20 min. Mean reduction in depression was 20.1±1%, N=9. Tachyphylaxis was less prominent in currents evoked by AMPA or NMDA, appearing in two of 10 AMPA and three of 11 NMDA currents.
The mGluR agonist trans‐(1S,3R)‐1‐amino‐1,3‐cyclopentanedicarboxylic acid (ACPD) increased, the antagonist (±)‐alpha‐methyl‐4‐carboxyphenylglycine (MCPG) decreased the area of glutamate‐evoked currents. ACPD also increased the area of NMDA‐ and AMPA‐evoked currents.
ACPD increased the incidence of tachyphylaxis in glutamate‐evoked currents to 100% (N=9); MCPG markedly reduced tachyphylaxis. ACPD also increased the incidence of tachyphylaxis in currents evoked by NMDA and AMPA to five of eight and four of seven neurons, respectively.
Block of G‐protein pathways by intracellular GDP‐β‐s abolished tachyphylaxis in glutamate‐evoked currents (N=8); however, currents recovered only partially following EtOH washout.
Activation of mGluRs contributes to neuronal tachyphylaxis to EtOH in spinal cord motorneurons, probably via G‐protein pathways.

British Journal of Pharmacology (2003) 138, 1417–1424. doi:10.1038/sj.bjp.0705175
Characterization of a fluorescent conjugate of the rabbit angiotensin AT1 receptor
Authors: Fortin Jean‐Philippe , Bouthillier Johanne , Bastien Luc , Bachvarov Dimcho R , Marceau François 
Published: April 2003

The rabbit AT1 receptor (AT1R) for angiotensin II (AII) has been conjugated to the yellow fluorescent protein (YFP) in order to establish the pharmacological profile of such a fusion protein and to facilitate the study of ligand‐induced regulation.
AII bound AT1R–YFP (KD 8.1 nM in transiently transfected cells) and stimulated HEK 293 cells expressing the fusion protein at concentration ranges similar to the ones that stimulate the contraction of the isolated rabbit aorta. Antagonists found to be insurmountable in the latter assay (candesartan and EXP‐3174 being the most extreme cases) were also insurmountable in the phospholipase A2 assay applied to cells expressing AT1R–YFP, whereas losartan appeared to be surmountable in both assays.
Cells expressing AT1R–YFP exhibited a membrane‐associated fluorescence that was partly and reversibly translocated into intracellular structures upon AII stimulation (confocal microscopy); the nonpeptide antagonists were not active in this respect, but prevented the effect of the agonist.
AII treatment increased the quantity of the fusion protein in cells, and phorbol 12‐myristate 13‐acetate (PMA) treatment even more so (immunoblot, confocal microscopy) but, unlike the agonist, the latter drug did not induce receptor endocytosis. A protein kinase C (PKC) inhibitor prevented the effect of either AII or PMA on AT1R–YFP abundance.
The conjugate AT1R–YFP retains the pharmacological properties of the parent rabbit AT1R. Agonist‐induced downregulation was not documented using this system; to the contrary, we have observed a PKC‐mediated increased expression AT1R–YFP likely to be the result of a decreased breakdown rate of the fusion protein.

British Journal of Pharmacology (2003) 138, 1495–1504. doi:10.1038/sj.bjp.0705176
Identification and functional characterization of hemorphins VV‐H‐7 and LVV‐H‐7 as low‐affinity agonists for the orphan bombesin receptor subtype 3
Authors: Lammerich Hans‐Peter , Busmann Annette , Kutzleb Christian , Wendland Martin , Seiler Petra , Berger Claudia , Eickelmann Peter , Meyer Markus , Forssmann Wolf‐Georg , Maronde Erik 
Published: April 2003

The human orphan G‐protein coupled receptor bombesin receptor subtype 3 (hBRS‐3) was screened for peptide ligands by a Ca2+ mobilization assay resulting in the purification and identification of two specific ligands, the naturally occurring VV‐hemorphin‐7 (VV‐H‐7) and LVV‐hemorphin‐7 (LVV‐H‐7), from human placental tissue. These peptides were functionally characterized as full agonists with unique specificity albeit low affinity for hBRS‐3 compared to other bombesin receptors.
VV‐H‐7 and LVV‐H‐7 induced a dose‐dependent response in hBRS‐3 overexpressing CHO cells, as well as in NCI‐N417 cells expressing the hBRS‐3 endogenously. The affinity of VV‐H‐7 was higher in NCI‐N417 cells compared to overexpressing CHO cells. In detail, the EC50 values were 45±15 μM for VV‐H‐7 and 183±60 μM for LVV‐H‐7 in CHO cells, and 19±6 μM for VV‐H‐7 and 38±18 μM for LVV‐H‐7 in NCI‐N417 cells. Other hemorphins had no effect. Gastrin‐releasing peptide (GRP) and neuromedin B (NMB) showed similar EC50 values of 13–20 μM (GRP) and of 1–2 μM (NMB) on both cell lines.
Structure‐function analysis revealed that both the N‐terminal valine and the C‐terminal phenylalanine residues of VV‐H‐7 are critical for the ligand‐receptor interaction.
Endogenous hBRS‐3 in NCI‐N417 activated by VV‐H‐7 couples to phospholipase C resulting in changes of intracellular calcium, which is initially released from an inositol trisphosphate (IP3)‐sensitive store followed by a capacitive calcium entry from extracellular space.
VV‐H‐7‐induced hBRS‐3 activation led to phosphorylation of p42/p44‐MAP kinase in NCI‐N417 cells, but did not stimulate cell proliferation. In contrast, phosphorylation of focal adhesion kinase (p125FAK) was not observed.

British Journal of Pharmacology (2003) 138, 1431–1440. doi:10.1038/sj.bjp.0705177
Effects of U‐50,488H and U‐50,488H withdrawal on c‐fos expression in the rat paraventricular nucleus. Correlation with c‐fos in brainstem catecholaminergic neurons
Authors: Laorden Maria Luisa , Castells Maria Teresa , Milanés Maria Victoria 
Published: April 2003

In the present work, we have studied the expression of Fos during acute and chronic administration of the κ‐opioid receptor agonist U‐50,488H and after U‐50,88H withdrawal in the rat hypothalamic paraventricular nucleus (PVN). Fos production was also studied in brainstem regions that innervate the PVN: the A2 cell group of the nucleus of solitary tract (NTS‐A2) and the A1 cell group of the ventrolateral medulla (VLM‐A1), combined with immunostaining for tyrosine hydroxylase (TH) for immunohistochemical identification of active neurons after acute U‐50,488H administration.
For acute experiments, male rats were treated with saline i.p. for 4 days. On day 5, rats were given saline or U‐50,488H (15 mg kg−1, i.p.). Other groups of rats were rendered tolerant/dependent on U‐50,488H by injecting the drug twice daily (15 mg kg−1, i.p.) for 4 days. Control animals received saline i.p. on the same time schedule. On day 5, rats were treated with vehicle i.p., with U‐50,488H (15 mg kg−1) or with the selective κ opioid‐receptor antagonist nor‐binaltorphimine (Nor‐BNI, 5 mg kg−1, i.p.).
Using immunohistochemical staining of Fos, present results indicate that acute administration of U‐50,488H produced an increase in Fos expression in the PVN and in the noradrenergic A1 and A2 cell groups. Moreover, when double‐label immunohistochemistry was used to identify Fos and catecholaminergic‐positive neurons in the brainstem, it was found that catecholaminergic‐positive neurons in the NTS and VLM showed a significant increase in Fos expression in response to acute U‐50,488H injection. Chronic application of U‐50,488H leads to the development of tolerance towards their effects on Fos expression in the PVN as well as in the NTS and VLM. However, administration of Nor‐BNI to U‐50,488H‐dependent rats did not induce any changes in Fos immunoreactivity in the PVN or in the brainstem.
These findings demonstrate that acute activation of κ‐opioid receptors results in different altered patterns of immediate‐early gene expression in the PVN, which occurs concurrently with an increased activity of their inputs from the brainstem. Interestingly in contrast to morphine withdrawal, present results demonstrate that rats withdrawn from U‐50,488H did show no changes in Fos‐immunoreactivity in the PVN, NTS or VLM, indicating the absence of dependence on the κ‐agonist under the present experimental conditions.

British Journal of Pharmacology (2003) 138, 1544–1552. doi:10.1038/sj.bjp.0705179
Extracellular nucleotides induce vasodilatation in human arteries via prostaglandins, nitric oxide and endothelium‐derived hyperpolarising factor
Authors: Wihlborg Anna‐Karin , Malmsjö Malin , Eyjolfsson Atli , Gustafsson Ronny , Jacobson Kenneth , Erlinge David 
Published: April 2003

The present study was aimed at examining P2 receptor‐mediated vasodilatation in human vessels. The isometric tension was recorded in isolated segments of the human left internal mammary artery branches precontracted with 1 μM noradrenaline.
Endothelial denudation abolished the dilator responses.
The selective P2Y1 agonist, 2‐MeSADP, induced a potent vasodilatation (pEC50=6.9±0.1). The P2Y1 antagonist of 10 μM, MRS 2216, shifted the 2‐MeSADP concentration‐response curve 1.1 log units to the right. The combined P2Y1 and P2X agonist, 2‐MeSATP, stimulated a dilatation with a potency similar to that of 2‐MeSADP. Furthermore, MRS 2216 had a similar antagonistic effect on both 2‐MeSATP and 2‐MeSADP indicating that P2X receptors do not mediate vasodilatation.
Both the P2Y2/4 agonist, UTPγS and the P2Y6 agonist, UDPβS, stimulated potent dilatations (pEC50=7.8±0.4 for UTPγS and 8.4±0.2 for UDPβS).
The 2‐MeSADP‐induced nitric oxide (NO)‐mediated dilatation was studied in the presence of 10 μM indomethacin, 50 nM charybdotoxin and 1 μM apamin. The involvement of the endothelium‐derived hyperpolarising factor (EDHF) was investigated in the presence of 0.1 mM L‐NOARG and indomethacin. The involvement of prostaglandins was investigated in the presence of L‐NOARG, charybdotoxin and apamin. Both NO, EDHF and prostaglandins mediated 2‐MeSADP dilatation with similar efficacy (Emax=25±5% for NO, 25±6% for EDHF and 27±5% for prostaglandins).
In conclusion, extracellular nucleotides induce endothelium‐derived vasodilatation in human vessels by stimulating P2Y1, P2Y2/4 and P2Y6 receptors, while P2X receptors are not involved. Endothelial P2Y receptors mediate dilatation by release of EDHF, NO and prostaglandins

British Journal of Pharmacology (2003) 138, 1451–1458. doi:10.1038/sj.bjp.0705186
Polarized Th1 and Th2 cells are less responsive to negative feedback by receptors coupled to the AC/cAMP system compared to freshly isolated T cells
Authors: Heijink Irene H , Vellenga Edo , Borger Peter , Postma Dirkje S , Monchy Jan G R de , Kauffman Henk F 
Published: April 2003

The adenylyl cyclase (AC)/cyclic adenosine monophosphate (cAMP) system is known to negatively regulate transcriptional activity of T cells, thereby possibly modulating T‐cell‐mediated responses at the sites of inflammation. Effects of cAMP have been widely studied in freshly isolated T cells and T‐cell clones; yet, effects in differentiated Th1 and Th2 cells are largely unknown.
To obtain differentiated T helper cells, we activated naive T cells for 1 week in the presence of IL‐12 plus α‐IL‐4 to generate Th1‐type cells and in the presence of IL‐4 plus α‐IL‐12 to generate Th2‐type cells.
We demonstrate that, in contrast to freshly isolated T cells, the production of Th1 (IFN‐γ) and Th2 (IL‐4, IL‐5) cytokines in polarized T helper cells is not strictly controlled by the activation of AC/cAMP‐linked β2‐adrenergic and prostaglandin (PG)E2 receptors.
In Th2 cells, PGE2 could still activate the Gs protein‐coupled AC/cAMP system and subsequently induce CREB phosphorylation, whereas PGE2 was unable to activate the cAMP‐dependent pathway in Th1 cells. In both Th1 and Th2 cells, the induction of CREB phosphorylation by β2‐agonist fenoterol was impaired.
The loss of control over cytokine production by cAMP elevating agents in differentiated Th1 and Th2 subsets may have important implications for the regulation of Th1‐ and Th2‐mediated diseases, in particular those associated with the ongoing immune responses.

British Journal of Pharmacology (2003) 138, 1441–1450. doi:10.1038/sj.bjp.0705193
Cannabinoid CB1 receptor‐mediated inhibition of hippocampal acetylcholine release is preserved in aged mice
Authors: Redmer Agnes , Kathmann Markus , Schlicker Eberhard 
Published: April 2003

The cannabinoid CB1 receptor inverse agonist/antagonist SR 141716 increases acetylcholine release in rodent hippocampus and improves memory in some experimental paradigms. Since drugs like SR 141716 may represent a novel class of cognition‐enhancing drugs, we wanted to check whether the function of the CB1 receptor is preserved during ageing.
Hippocampal and striatal slices from 2‐ to 3‐ and 24‐ to 28‐month‐old C57BL/6J mice were preincubated with [3H]‐choline or [3H]‐noradrenaline ([3H]‐NA) and superfused.
The cannabinoid receptor agonist WIN 55,212‐2 inhibited, and SR 141716 facilitated, the electrically (3 Hz) evoked tritium overflow in hippocampal slices (preincubated with [3H]‐choline) from young and aged mice to the same extent. The evoked overflow per se was less by 33% in slices from aged animals.
WIN 55,212‐2 and SR 141716 did not affect, but the muscarinic receptor agonist oxotremorine inhibited, the evoked (3 Hz) overflow in striatal slices (preincubated with [3H]‐choline) from young and aged mice to the same extent. The evoked overflow per se tended to be less in slices from aged animals.
The evoked (0.3 Hz) overflow in hippocampal slices (preincubated with [3H]‐NA) was not affected by WIN 55,212‐2 and SR 141716, but was inhibited by histamine (via H3 receptors) in slices from young mice and, to a somewhat less extent, in slices from aged mice. The evoked overflow per se did not differ between age groups.
In conclusion, the function of the CB1 receptor involved in the tonic inhibition of hippocampal acetylcholine release is preserved in aged mice.

British Journal of Pharmacology (2003) 138, 1425–1430. doi:10.1038/sj.bjp.0705194
Effects of flecainide and quinidine on Kv4.2 currents: voltage dependence and role of S6 valines
Authors: Caballero Ricardo , Pourrier Marc , Schram Gernot , Delpón Eva , Tamargo Juan , Nattel Stanley 
Published: April 2003

The effects of flecainide and quinidine were studied on wild‐type Kv4.2 channels (Kv4.2WT), channels with deletion of the N‐terminal domain (N‐del) and channels with mutations in the valine residues located at positions 402 and 404 in the presence (V[402,404]I) or in the absence (N‐del/V[402,404]I) of the N‐terminus.
The experiments were performed at 37°C on COS7 cells using the whole‐cell configuration of the patch‐clamp technique.
Flecainide and quinidine inhibited Kv4.2WT currents in a concentration‐dependent manner (IC50=23.6±1.1 and 12.0±1.4 μMat +50 mV, respectively), similar to their potency for the rest of the constructs at the same voltage. In Kv4.2WT channels, flecainide‐ and quinidine‐induced block increased as channel inactivation increased. In addition, the inhibition produced by quinidine, but not by flecainide, increased significantly at positive test potentials. Similar effects were observed in N‐del channels. However, in V[402,404]I and N‐del/V[402,404]I channels, the voltage dependence of block by both quinidine and flecainide was lost, without significant modifications in potency at +50 mV.
These results point to an important role for S6 valines at positions 402 and 404 in mediating voltage‐dependent block by quinidine and flecainide.

British Journal of Pharmacology (2003) 138, 1475–1484. doi:10.1038/sj.bjp.0705199
Benzoquinolines and chloride secretion in murine colonic epithelium
Authors: Cuthbert Alan W 
Published: April 2003

In all, 27 compounds related chemically to phenanthrolines were investigated for their ability to stimulate electrogenic chloride secretion in murine colonic epithelia under short circuit current conditions. A total of 11 compounds, not previously examined, were shown to have substantial activity. Cumulative concentration – response relations were obtained in the presence of amiloride to inhibit electrogenic sodium absorption and Ba2+ to prevent potassium secretion.
Single‐ or double‐ring substitutions in 1,10 phenanthroline (EC50=612 μM) produced only modest increases in affinity of between 0.7‐ and 2.1‐fold.
Naphthalenes with either one or two ring nitrogens showed some activity but had very low affinity, yet some (e.g. isoquinoline, EC50=700 μM) were able to produce maximal responses.
Removal of one nitrogen from 1,10‐phenanthroline or from 4,7‐phenanthroline gave, respectively, 7,8‐benzoquinoline and 5,6‐benzoquinoline. These two were the most active compounds found, the EC50 for 5,6‐benzoquinoline being 29 μM.
Most concentration – response curves were steep with Hill slopes of approximately 3. At high concentration, some compounds inhibited the response, producing a characteristic bell shape.
5,6‐ and 7,8‐benzoquinoline may be useful starting points for the synthesis of more potent agents by the addition of ring substituents.

British Journal of Pharmacology (2003) 138, 1528–1534. doi:10.1038/sj.bjp.0705203