bluuebunny/crossref_metadata_2025_split huggingface dataset:
Involvement of protein kinase C in the UTP‐mediated potentiation of cyclic AMP accumulation in mouse J774 macrophages
Authors: Lin W. W. , Chen B. C. 
Published: August 2006

We have investigated the effects of nucleotide analogues on cyclic AMP formation in mouse J774 macrophages and the mechanisms involved.
UTP, in the concentration range 0.1–100 μM, induced concentration‐dependent potentiation of prostaglandin E1 (PGE1)‐induced cyclic AMP formation, but had no effect on basal cyclic AMP formation. UDP showed an equal potency, while 2‐methylthio ATP, α,β‐methylene ATP and β,γ‐methylene ATP gave either a slight increase or had no effect at concentrations up to 100 μM. ATP, although 100 fold less effective than UTP, also caused cyclic AMP potentiation, but had no effect on agonist‐stimulated or basal cyclic AMP levels.
The cyclic AMP potentiation effect of UTP correlated with increased [Ca2+]i and inositol phosphate (IP) formation over the same concentration range.
Ionomycin, which evokes an increase in [Ca2+]i without affecting IP formation, did not cause an increase in cyclic AMP content, indicating that UTP‐induced cyclic AMP regulation is not due to activation of Ca2+‐sensitive adenylyl cyclase isoforms.
Although reduced, UTP potentiation was seen in cells incubated in a Ca2+‐free and/or BAPTA‐containing medium. Under these conditions, the UTP‐increased IP accumulation was similarly reduced.
Exposure of cells to phorbol 12‐myristate 13‐acetate (PMA) also increased PGE1 stimulation of cyclic AMP levels, and the UTP‐induced potentiation of cyclic AMP formation was inhibited by either staurosporine or Ro 31‐8220. Pretreatment of cells with PMA for 4–24 h resulted in marked attenuation of UTP‐stimulated cyclic AMP potentiation.
Pretreatment with pertussis toxin (24 h, 100 ng ml−1) did not significantly affect UTP‐induced cyclic AMP potentiation and IP formation, although it increased the cyclic AMP response to PGE1.
Analysis of J774 cells by Western blotting with antibodies specific for different protein kinase C (PKC) isoforms shows the presence of the βI, βII, δ, ε, ζ, μ, λ and ζ isoforms. Moreover, UTP significantly increased the level of PKC βI, βII, δ, ε, μ, λ and ζ immunoreactivity in the membrane fraction and decreased the cytosolic reactivity of PKC βII, δ, ε and ζ.
Immunoblot studies also indicate the presence of type II adenylyl cyclase.
These results indicate that PKC is required for the potentiation of adenylyl cyclase activity by macrophage pyrimidinoceptors, which exhibit a higher specificity for UTP and UDP than for ATP.

British Journal of Pharmacology (1997) 121, 1749–1757; doi:10.1038/sj.bjp.0701300
Inhibition by cannabinoid receptor agonists of acetylcholine release from the guinea‐pig myenteric plexus
Authors: Coutts Angela A. , Pertwee Roger G. 
Published: August 2006

The dose‐related inhibition of the twitch responses of the myenteric plexus‐longitudinal muscle preparation of the guinea‐pig small intestine by cannabinoid (CB) agonists, (+)‐WIN 55212 and CP 55940 during stimulation at 0.1 Hz with supramaximal voltage was confirmed. These agonists inhibited acetylcholine (ACh) release in the presence of physostigmine (7.7 μM) thus indicating a prejunctional site of action.
Inhibition of twitch responses and ACh release by CB agonists was reversed by the CB1‐selective cannabinoid receptor antagonist, SR141716A. Dose‐response curves to (+)‐WIN 55212 and CP 55940 were shifted to the right, with no reduction of maximal response, by pretreatment with SR141716A (31.6–1000 nM), but not its vehicle, Tween 80 (1 μM). However, at very high concentrations (25–400 μM), Tween 80 itself caused a dose‐related inhibition of the twitch response which was significantly reduced in the presence of SR141716A (1 μM). The opioid receptor antagonist, naloxone (1 μM) had no significant effect on the inhibition by CP 55940 of the twitch response.
(+)‐WIN 55212, CP 55940 and Tween 80 (50 μM) had no effect on responses to exogenous ACh, confirming that their actions were prejunctional. SR141716A (1 μM) did not increase the sensitivity of the longitudinal muscle to either ACh or histamine, but inhibited the responses to high doses of ACh.
The (−)‐enantiomer of WIN 55212, was approximately 300 times less active than the (+) enantiomer in inhibiting the twitch response, had no CB1 antagonist activity against the active isomer and did not inhibit the release of ACh in the presence of physostigmine.
The dissociation constant (KD) values for SR 141716A against the inhibitory effect of (+)‐WIN 55212 and CP 55940 on the twitch response were 12.07 nM (95% confidence intervals 8.55 and 20.83) and 6.44 nM (95% confidence intervals 4.70 and 10.24), respectively. In experiments in which the release of ACh was inhibited by (+)‐WIN 55212, the KD values were 9.21 nM and 10.53 nM at SR141716A concentrations of 31.6 nM and 100 nM, respectively. The KD values for the antagonism by naloxone of the inhibition of the twitch responses and the inhibition of ACh release by normorphine in this preparation were found to be 2.38±0.69 nM and 2.00±0.9 nM, respectively.
During maximal inhibition of ACh release by (+)‐WIN 55212, the addition of normorphine (400 nM) caused a further significant decrease in ACh output.
SR141716A alone produced a significant increase in ACh release in both the absence and presence of exogenous cannabinoid drugs, hence we conclude that it has a presynaptic site of action. We also conclude that SR141716A acts either by antagonizing the effect of an endogenous CB1 receptor agonist or by having an inverse agonist effect at these receptors.

British Journal of Pharmacology (1997) 121, 1557–1566; doi:10.1038/sj.bjp.0701301
Evidence that methyl arachidonyl fluorophosphonate is an irreversible cannabinoid receptor antagonist
Authors: Fernando Susanthi R. , Pertwee Roger G. 
Published: August 2006

Methyl arachidonyl fluorophosphonate (MAFP) (1 μM) significantly attenuated the ability of WIN 55,212‐2, CP 55,940, (−)‐Δ9‐tetrahydrocannabinol (THC), nabilone and (R)‐(+)‐arachidonoyl‐1′‐hydroxy‐2′‐propylamide (methanandamide) to inhibit electrically‐evoked isometric contractions of the myenteric plexus‐longitudinal muscle preparation of guinea‐pig small intestine.
The sizes of the maximal responses to WIN 55,212‐2 and CP 55,940 decreased significantly in the presence of 1 μM MAFP.
MAFP (1 μM) essentially abolished the inhibitory effects on the twitch response of the highest concentration of methanandamide used (3.162 μM). The dextral shift it induced in the log concentration‐response curve of nabilone was non‐parallel. In contrast, the dextral shift in the log concentration‐response curve of THC produced by MAFP did not deviate significantly from parallelism and was relatively small with a mean value of 3.45 and 95% confidence limits of 1.19 and 13.08.
MAFP (1 μM) did not attenuate the effects of normorphine or clonidine on the twitch response of the myenteric plexus‐longitudinal muscle preparation or affect the contractile response of this preparation to acetylcholine.
When administered by itself at concentrations of 1 to 1000 nM, MAFP had no detectable effect on the twitch response of the myenteric plexus‐longitudinal muscle preparation.
These results support the hypothesis that MAFP is an irreversible cannabinoid CB1 receptor antagonist that possesses some degree of selectivity.

British Journal of Pharmacology (1997) 121, 1716–1720; doi:10.1038/sj.bjp.0701303
Investigation of the mechanisms underlying the hypophagic effects of the 5‐HT and noradrenaline reuptake inhibitor, sibutramine, in the rat
Authors: Jackson Helen C. , Bearham M. Clair , Hutchins Lisa J. , Mazurkiewicz Sarah E. , Needham Andrew M. , Heal David J. 
Published: August 2006

Sibutramine is a novel 5‐hydroxytryptamine (5‐HT) and noradrenaline reuptake inhibitor (serotonin‐ noradrenaline reuptake inhibitor, SNRI) which is currently being developed as a treatment for obesity. Sibutramine has been shown to decrease food intake in the rat. In this study we have used a variety of monoamine receptor antagonists to examine the pharmacological mechanisms underlying sibutramine‐induced hypophagia.
Individually‐housed male Sprague‐Dawley rats were maintained on reversed phase lighting with free access to food and water. Drugs were administered at 09 h 00 min and food intake was monitored over the following 8 h dark period.
Sibutramine (10 mg kg−1, p.o.) produced a significant decrease in food intake during the 8 h following drug administration. This hypophagic response was fully antagonized by the α1‐adrenoceptor antagonist, prazosin (0.3 and 1 mg kg−1, i.p.), and partially antagonized by the β1‐adrenoceptor antagonist, metoprolol (3 and 10 mg kg−1, i.p.) and the 5‐HT receptor antagonists, metergoline (non‐selective; 0.3 mg kg−1, i.p.); ritanserin (5‐HT2A/2C; 0.1 and 0.5 mg kg−1, i.p.) and SB200646 (5‐HT2B/2C; 20 and 40 mg kg−1, p.o.).
By contrast, the α2‐adrenoceptor antagonist, RX821002 (0.3 and 1 mg kg−1, i.p.) and the β2‐adrenoceptor antagonist, ICI 118,551 (3 and 10 mg kg−1, i.p.) did not reduce the decrease in food intake induced by sibutramine.
These results demonstrate that β1‐adrenoceptors, 5‐HT2A/2C‐receptors and particularly α1‐adrenoceptors, are involved in the effects of sibutramine on food intake and are consistent with the hypothesis that sibutramine‐induced hypophagia is related to its ability to inhibit the reuptake of both noradrenaline and 5‐HT, with the subsequent activation of a variety of noradrenaline and 5‐HT receptor systems.

British Journal of Pharmacology (1997) 121, 1613–1618; doi:10.1038/sj.bjp.0701311
Study of the in vivo and in vitro cardiovascular effects of a hydralazine‐like vasodilator agent (HPS‐10) in normotensive rats
Authors: Orallo Francisco 
Published: August 2006

In this work, the cardiovascular effects of HPS‐10, a new vasodilator agent, were studied in rats.
In conscious normotensive rats, oral administration of HPS‐10 (4–9 mg kg−1) produced a dose‐related and long‐lasting fall in systolic arterial blood pressure (ED30 of 5.32 mg kg−1), accompanied by an increase in heart rate (ED30 of 8.43 mg kg−1). This tachycardia was totally inhibited by pretreatment with (±)‐propranolol (10 mg kg−1, p.o.).
In anaesthetized normotensive rats, HPS‐10 (0.3–0.6 mg kg−1, i.v.) produced a gradual, dose‐dependent and sustained decrease in systolic, diastolic and mean arterial pressure (MAP) (ED30 for MAP of 0.41 mg kg−1, i.v.), accompanied by a significant bradycardia at high doses (>0.4 mg kg−1; ED20 of 0.61 mg kg−1, i.v.). HPS‐10 (0.5 mg kg−1, i.v.) did not modify the positive chronotropic effects induced by intravenous administration of noradrenaline (NA; 5 μg kg−1), angiotensin II (AII; 0.2 μg kg−1) and nicotine (200 μg kg−1) but markedly inhibited the hypertensive response produced by these agents.
In rat isolated rubbed aorta, HPS‐10 (0.1–1 mM) non‐competitively and with almost equal effectiveness antagonized the contractions induced by NA, AII (in normal Krebs solution) and Ca2+ (in depolarizing Ca2+‐free high‐K+ 50 mM solution). In the experiments in Ca2+‐free medium, HPS‐10 (1 mM) considerably inhibited the contractions induced by NA, AII and caffeine in rat aorta.
Furthermore, in the studies with radioactive Ca2+, HPS‐10 (1 mM) did not modify the basal uptake of 45Ca2+ but strongly decreased the influx of 45Ca2+ induced by NA, AII and K+ in rat aortic rings.
In rat isolated atria, HPS‐10 (1 mM) produced a positive inotropic/negative chronotropic effect.
HPS‐10 (0.3 mM) significantly inhibited the sustained and transient Ba2+ inward current (IBa) recorded in whole‐cell clamped rat aortic myocytes.
These results indicate that the non‐selective vasorelaxant effects of HPS‐10 in rat aortic rings can be attributed to transmembrane Ca2+‐antagonist activity and an intracellular action on smooth muscle cells. The direct vasodilator action of HPS‐10 observed in rat isolated aorta may be responsible for the HPS‐10 hypotensive activity in anaesthetized normotensive rats.

British Journal of Pharmacology (1997) 121, 1627–1636; doi:10.1038/sj.bjp.0701314
Differential effect of L‐NAME and S‐methyl‐isothiourea on leukocyte emigration in carrageenin‐soaked sponge implants in rat
Authors: Iuvone Teresa , Van Osselaer Nancy , D'Acquisto Fulvio , Carnuccio Rosa , Herman Arnold G. 
Published: August 2006

The role of nitric oxide (NO) in leukocyte (polymorphonuclear cells, monocytes and lymphocytes) emigration was studied in a model of carrageenin‐sponge implants in rats.
The subcutaneous implantation of 1% (w/v) of λ‐carrageenin‐soaked sponges elicited an inflammatory response that was characterized by a time‐related increase in leukocyte infiltration in the sponges and increased levels of nitrite in the exudate. Total leukocyte infiltration and nitrite production were maximal at 24 h and decreased after 48 and 96 h. The mononuclear cell influx was maximal at 48 h (21% of the total leukocytes). Therefore, this time point was used in the successive experiments.
Polymorphonuclear cell (PMN) and lymphocyte infiltration in the sponges significantly increased when rats were treated with the non‐specific NO‐synthase (NOS) inhibitor, NG‐nitro‐L‐arginine methylester (L‐NAME) (1 mg ml−1 in drinking water ad libitum). Monocyte emigration was not affected by L‐NAME treatment. The nitrite levels in the exudate of L‐NAME‐treated rats were significantly reduced. The concomitant ingestion of L‐arginine (30 mg ml−1) resulted in a reversion of the L‐NAME effect, while D‐arginine (30 mg ml−1) had no effect, indicating the involvement of the L‐arginine: NO pathway.
Administration of L‐NAME resulted also in an increased release of tumour necrosis factor‐α (TNF‐α) and prostacyclin (measured as the stable metabolite, 6‐keto‐PGF1α). L‐NAME had no effect on monocyte chemoattractant protein‐1 (MCP‐1) release in the exudate.
Since L‐NAME may have effects on the local blood flow, phenylephrine (0.034 mg ml−2 in drinking water) was used as it has an effect on the local blood flow similar to L‐NAME. Phenylephrine had no effect on either leukocyte emigration, or on nitrite, TNF‐α, prostacyclin or MCP‐1 accumulation in the exudate.
In contrast, the more selective iNOS inhibitor S‐methyl‐isothiourea (SMT) (10 μg ml−1 in drinking water) significantly reduced PMNs and lymphocyte influx in the sponge, having no effect on monocyte influx. Moreover, SMT decreased nitrite production in the exudate to a comparable extent as L‐NAME.
Administration of SMT significantly reduced MCP‐1 release in the exudate, without an effect on TNF‐α or prostacyclin production. Moreover SMT did not produce any changes in local blood flow.
Our results show that a different outcome of the inflammatory process can be obtained depending on the types of NOS inhibitor used.

British Journal of Pharmacology (1997) 121, 1637–1644; doi:10.1038/sj.bjp.0701317
Capsaicin and neurokinin A‐induced bronchoconstriction in the anaesthetised guinea‐pig: evidence for a direct action of menthol on isolated bronchial smooth muscle
Authors: Wright C. E. , Laude E. A. , Grattan T. J. , Morice A. H. 
Published: August 2006

For many years menthol has been used in the treatment of respiratory disorders although, a bronchodilator effect of menthol has yet to be described. Using the bronchoconstrictors capsaicin (acting via stimulating the release of neuropeptides from sensory afferents) and neurokinin A (NKA) we have raised airways resistance in the guinea‐pig (GP) and studied the effect of menthol on both capsaicin and NKA‐induced bronchoconstriction in vivo. In vitro the effect of menthol on acetylcholine (ACh) and KCl precontracted GP bronchi was also studied.
GP (n=13) were anaesthetized (urethane 1.5 g kg−1, i.p.) and a bolus injection of capsaicin (7.5 μg ml−1, i.v.) or infusion of NKA (1 μg min−1, i.v.) was given either in the presence of air (0.81 min−1) or air impregnated with menthol vapour (7.5 μg l−1) freely breathed from a tracheal cannula via a T‐piece. Airways resistance (Raw) and ventilation were measured throughout. Bronchi of mean internal diameter (1029+73.6 μm; n=24) were removed from GP (n=16) and mounted in the Cambustion myograph. Bronchial rings were maximally precontracted with 80 mM KC1 or 2 mM ACh. Relaxation due to a cumulative dose of menthol (1–3000 μM) was measured.
Menthol produced a significant (P<0.05) 51.3% reversal of the capsaicin‐induced increase in Raw, and also inhibited the significant (P<0.05) reduction in minute ventilation (Ve) associated with the capsaicin‐induced increased in Raw. Menthol also caused a significant (P<0.05) 41% reversal of the NKA‐induced increase in Raw. The NKA‐induced decrease in Ve was again significantly (P<0.05) reversed with menthol inhalation. Menthol caused a significant (P<0.001) dose‐dependent relaxation of KCl and ACh precontracted bronchi.
We have shown that menthol attenuates both capsaicin and NKA‐induced bronchoconstriction in vivo and relaxes KCl and ACh preconstricted bronchi in vitro. Menthol inhibition of NKA and capsaicin‐induced bronchoconstriction could be, in part, explained by a direct action of menthol on bronchial smooth muscle.

British Journal of Pharmacology (1997) 121, 1645–1650; doi:10.1038/sj.bjp.0701319
The role of cyclic nucleotides in guinea‐pig bladder contractility
Authors: Longhurst Penelope A. , Briscoe Janice A K. , Rosenberg David J. , Leggett Robert E. 
Published: August 2006

The effects of phosphodiesterase (PDE) inhibition and forskolin pretreatment on the contractile responses of guinea‐pig urinary bladder strips to electrical field stimulation, carbachol, ATP and KCl were studied.
Inhibition of cyclic AMP‐specific PDE4 isozymes by rolipram significantly reduced the contractile response of bladder strips to field stimulation. Rolipram also suppressed the contractile response to low concentrations of carbachol, but potentiated the response to high concentrations. The contractile response to ATP was significantly reduced by rolipram treatment, but that to KCl was unaltered.
Inhibition of cyclic GMP‐specific PDE5 isozymes by zaprinast had no effects on the contractile response of bladder strips to field stimulation, ATP or KCl. Zaprinast suppressed the contractile responses to 1 μM carbachol and potentiated the response to high concentrations.
Contractile responses to field stimulation and to carbachol after pretreatment with the adenylyl cyclase activator, forskolin, were qualitatively similar to those caused by rolipram treatment. β‐Adrenoceptor blockade with propranolol partially reversed the inhibitory effects of rolipram on the response to field stimulation.
Rolipram significantly reduced the contractile response of bladder strips from sensitized guinea‐pigs to ovalbumin challenge, but zaprinast was ineffective. PDE inhibition had similar effects on the responsiveness of control and of sensitized guinea‐pig bladder strips to field stimulation, carbachol, ATP and KCl.
The data suggest that the contractile response of guinea‐pig bladder strips can be modified by increases in cyclic AMP levels.

British Journal of Pharmacology (1997) 121, 1665–1672; doi:10.1038/sj.bjp.0701328
Characterization of [3H]‐prostaglandin E2 binding to prostaglandin EP4 receptors expressed with Semliki Forest virus
Authors: Marshall Fiona H. , Patel Kalpana , Lundstrom Kenneth , Camacho Janet , Foord Steven M. , Lee Melanie G. 
Published: August 2006

The human prostaglandin EP4 receptor has been expressed by use of the Semliki Forest virus system.
In cell membranes [3H]‐prostaglandin E2 ([3H]‐PGE2) bound to a high affinity site with a Kd of 1.12±0.3 nM and a Bmax of 3.1±0.3 pmol mg−1 protein.
In competition studies the rank order of potency for prostaglandins was PGE2  = PGE1  ∼#62;  PGF2α =PGI2.
The binding of [3H]‐PGE2 to cell membranes was inhibited by approximately 60% by the addition of guanylnucleotides, suggesting that this proportion of the receptors was G‐protein coupled.
[3H]‐PGE2 binding was increased by greater than 200% by the addition of divalent cations, with little change in the IC50 of PGE2.
In saturation studies removal of divalent cations and addition of GTPγS resulted in a 65% reduction in the Bmax with no change in the Kd. These results are consistent with the ligand labelling two states of the receptor R*, a high affinity state and R*G, a high affinity G protein coupled state.

British Journal of Pharmacology (1997) 121, 1673–1678; doi:10.1038/sj.bjp.0701332
Agonist and antagonist modulation of [35S]‐GTPγS binding in transfected CHO cells expressing the neurotensin receptor
Authors: Hermans Emmanuel , Geurts Muriel , Maloteaux Jean‐Marie 
Published: August 2006

The functional interaction of the cloned rat neurotensin receptor with intracellular G‐proteins was investigated by studying the binding of the radiolabelled guanylyl nucleotide analogue [35S]‐GTPγS induced by neurotensin to membranes prepared from transfected Chinese hamster ovary (CHO) cells.
The agonist‐induced binding of [35S]‐GTPγS was only detected in the presence of NaCl in the incubation buffer. However, it was also demonstrated that the binding of [3H]‐neurotensin to its receptor was inhibited by NaCl. In the presence of 50 mM NaCl, the binding of the labelled nucleotide was about 2 fold increased by stimulation with saturating concentrations of neurotensin (EC50 value of 2.3±0.9 nM).
The stimulation of [35S]‐GTPγS binding by neurotensin was mimicked by the stable analogue of neurotensin, JMV‐449 (EC50 value of 1.7±0.4 nM) and the neurotensin related peptide neuromedin N (EC50 value of 21±6 nM).
The NT‐induced [35S]‐GTPγS binding was competitively inhibited by SR48692 (pA2 value of 9.55±0.28), a non‐peptide neurotensin receptor antagonist. SR48692 alone had no effect on the specific binding of [35S]‐GTPγS.
The response to neurotensin was found to be inhibited by the aminosteroid U‐73122, a putative inhibitor of phospholipase C‐dependent processes, indicating that this drug may act at the G‐protein level.
Taken together, these results constitute the first characterization of the exchange of guanylyl nucleotides at the G‐protein level that is induced by the neuropeptide neurotensin after binding to its receptor.

British Journal of Pharmacology (1997) 121, 1817–1823; doi:10.1038/sj.bjp.0701334
Evidence that anandamide and EDHF act via different mechanisms in rat isolated mesenteric arteries
Authors: Plane F , Holland M , Waldron G. J. , Garland C. J. , Boyle J. P. 
Published: August 2006

The endogenous cannabinoid, anandamide, has been suggested as an endothelium‐derived hyperpolarizing factor (EDHF). We found that anandamide‐evoked relaxation in isolated segments of rat mesenteric artery was associated with smooth muscle hyperpolarization. However, although anandamide‐evoked relaxation was inhibited by either charybdotoxin (ChTX) or iberiotoxin, inhibition of the relaxation to EDHF required a combination of ChTX and apamin. The relaxations induced by either anandamide or EDHF were not inhibited by the cannabinoid receptor (CB1) antagonist SRI41716A, or mimicked by selective CB1 agonists. Thus, anandamide appears to cause smooth muscle relaxation via a CB1 receptor‐independent mechanism and cannabinoid receptor activation apparently does not contribute to EDHF‐mediated relaxation in this resistance artery. British Journal of Pharmacology (1997) 121, 1509–1511; doi:10.1038/sj.bjp.0701361