bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Calcium Blockers on the Cytosolic Calcium, H2O2Production and Elastase Release in Human Neutrophils
Authors: Haga Yoshiyuki , Dumitrescu Alexandra , Zhang Yu , Stain‐Malmgren Rigmor , Sjöquist Per‐Ove
Published: March 2009

Abstract:Activated neutrophils are assumed to be one plausible cause of tissue injury in the ischaemic and reperfused myocardium. We studied the inhibitory effects of the calcium antagonists felodipine, nimodipine and verapamil on human neutrophil activation in order to elucidate the mechanisms underlying their myocardioprotective effects and to determine whether calcium antagonists with different chemical structures vary in their effect on neutrophil activation. Neutrophils were stimulated with formyl‐Met‐Leu‐Phe (0.1 μM) or by phorbol myristate acetate (0.16 μM), and the rise in cytosolic calcium and the H2O2production were determined. For felodipine, the inhibitory effect on granulocyte elastase release was also studied. The calcium antagonists reduced formyl‐Met‐Leu‐Phe and phorbol myristate acetate‐induced neutrophil activation in a concentration‐dependent manner, the order of potency being: felodipine >nimodipine >verapamil. For felodipine, the IC50(concentration causing 50% reduction) values were 3×10−6and 2×10−6M for the formyl‐Met‐Leu‐Phe‐induced cytosolic calcium increase and H2O2production, respectively. The IC50‐value for the phorbol myristate acetate‐induced cytosolic calcium increase was 6×10−6and for H2O2production 4×10−6M. For formyl‐Met‐Leu‐Phe‐induced granulocyte elastase release, the IC50‐value was 5×10−6M. The inhibitory effect of felodipine on the phorbol myristate acetate‐induced granulocyte elastase release did not exceed 50%. Nimodipine was a less potent inhibitor than felodipine for both formyl‐Met‐Leu‐Phe‐ and phorbol myristate acetate‐induced cell activities. Verapamil was even less potent than the other two agents. The present study demonstrates that felodipine potentially suppresses neutrophil activation at micromolar concentrations. However, this observation should not be directly extrapolated to explain the tissue protection by the compounds without evidence of profound local accumulation.
Progesterone Modulation of Diazepam Withdrawal Syndrome in Mice
Authors: Pesce M. E. , Acevedo X. , Pinardi G. , Miranda H.F.
Published: March 2009

Abstract: The influence of progesterone and oestrogens on the benzodiazepine withdrawal syndrome in mice was studied. The intraperitoneal administration of 15 mg/kg of flumazenil induced a withdrawal syndrome in chronic diazepam‐treated mice, characterized by jerks, usually accompanied by tail lifts, and seizures. The principal finding of the present work is that the intensity of diazepam withdrawal syndrome was significantly reduced by acute administration of progesterone as revealed by a low incidence of jerks and seizures. The action of progesterone could be due to a modulatory role of the hormone on neuronal activity as an anxiolytic agent. The modulatory activity of progesterone appears to be related to changes in the pharmacological properties of benzodiazepine receptors.
Stable Guanosine 5′‐Triphosphate‐Analogues Inhibit Specific (+)‐[3H]Isradipine Binding in Rat Hearts by a Ca2+‐Lowering, G Protein‐Independent Mechanism
Authors: Stokke Mimi , Hagelin Else Marie , Mende Ulrike , Brørs Odd
Published: March 2009

Abstract:We investigated if and how stable guanosine 5′‐triphosphate‐analogues affect (+)‐[3H]isradipine binding in rat hearts. Gpp(NH)p and GTP‐γ‐S inhibit specific (+)‐[3H]isradipine binding in membranes and cell‐homogenates by reducing the binding density without changing the Kdor the k‐1. Inhibition by Gpp(NH)p was less in crude tissue homogenates than in membranes apparently due to a soluble factor. Pretreatment of cardiomyocytes with cholera toxin or the presence of the protein kinase A inhibitor, PKI6‐22, did not influence the effect of 10‐3M Gpp(NH)p on binding. The inhibitory effect of 10‐3M Gpp(NH)p was not significantly altered in membranes fromin vivopertussis toxin treated rats. The addition of 10‐3M Ca2+or Mg2+abolished the inhibitions. Gpp(NH)p in the concentration that inhibits binding, reduced the free concentration of Ca2+. The Ca2+‐lowering effect of 10‐3M Gpp(NH)p produced 70%, 60% and 100% of the inhibition in membranes, sonicated and unsonicated cell homogenates. Thus, Gpp(NH)p inhibited specific (+)‐[3H]isradipine binding mainly by lowering the free concentration of Ca2+by chelation and not by activation of cholera toxin or pertussis toxin‐sensitive G proteins or protein kinase A.
The Influence of Preanalytical Factors on Concentrations of Morphine and Metabolites in Patients Receiving Morphine
Authors: Westerling D. , Bengtsson H.‐I. , Thysell C. , Hoglund P.
Published: March 2009

Abstract: To examine the importance of preanalytical factors on the sample concentration of morphine, morphine‐3‐glucuronide and morphine‐6‐glucuronide, blood samples were drawn in sets of four from 21 patients who were given morphine due to chronic pain or as premedication prior to surgery. Three different sampling tubes, different combinations of incubation temperature and time, and different temperatures during centrifugation were used and compared to reference standard treatment of blood samples using analysis of variance. Blood samples taken in EDTA tubes produced significantly higher (4.8%) concentrations of morphine compared with the reference levels obtained in heparin glass tubes. Incubation of blood samples at body temperature resulted in significantly higher (4.4%) morphine levels compared to reference levels. None of the other conditions studied influenced the sample concentrations of morphine significantly. The levels of the metabolites were not significantly affected under any of the tested conditions. Even if the preanalytical factors investigated in this study had little influence on the results, a standardised procedure is recommended for handling of blood samples for analysis of morphine and its metabolites.
Effects of Propionic Acid and Pravastatin on HMG‐CoA Reductase Activity in Relation to Forestomach Lesions in the Rat
Authors: Bueld J. E. , Bannenberg G. , Netter K. J.
Published: March 2009

Abstract: Administration of 4% propionic acid in powdered diet to rats for 12 weeks induces severe hyperplastic lesions in the forestomach mucosa. The mechanisms underlying this damage are not yet clear. Several lipophilic 3‐hydroxy‐3‐methylglutaryl coenzyme A (HMG‐CoA) reductase inhibitors such as lovastatin and simvastatin produce forestomach lesions similar to propionic acid after oral administration and the degree of alterations is correlated with their in vitro inhibitory potency (Kloss et al. 1991). Therefore it is possible, that sustained inhibition of HMG‐CoA reductase and induction of hyperplasias may be somehow connected. For that reason we investigated, whether or not propionic acid has any influence on HMG‐CoA reductase activity in vitro and in vivo, because propionic acid has been suggested to suppress liver cholesterol synthesis, and also whether or not pravastatin, a more polar HMG‐CoA reductase inhibitor than lovastatin displays similar effects on forestomach mucosa. In untreated forestomach microsomes in vitro, propionic acid at a concentration of 51 mM (pH 5.7) inhibited HMG‐CoA reductase activity by 51±10%, but at pH 7.2 no inhibition of the enzyme could be detected. Furthermore 4% propionic acid‐treatment did not lower serum cholesterol. In contrast to lovastatin (Kloss et al. 1991), oral administration of pravastatin (up to 25% in the diet) did not produce any forestomach lesions in the rat. On the other hand, pretreatment with pravastatin revealed that HMG‐CoA reductase activity in microsomes exceeded the activity of control forestomach and liver microsomes by 4.9 fold and 6.7 fold respectively, whereas no induction of this enzyme (neither liver nor forestomach) could be observed by pretreatment with 4% propionic acid for 12 weeks. Despite increased hepatic HMG‐CoA reductase activity, pravastatin‐treatment significantly lowered serum cholesterol levels of rats. These results show that sustained inhibition of HMG‐CoA reductase activity in forestomach microsomes is not strongly connected with hyperplasia development.
Trimedoxime and HI‐6: Kinetic Comparison after Intravenous Administration to Mice
Authors: Milić B. , Maksimović M. , Nedelijković M.
Published: March 2009

Abstract: The intravenous pharmacokinetics of the oximes HI‐6 (pyridinium‐1‐(((4‐carbamoi 1‐pyridinio)metoxy)rnethyl)‐2‐(hydroxyiminomethyl)dichloride monohydrate), (132.54 μmol/kg) and trimedoxime (1,1′‐(1,3′‐propanedyl)bis((4‐hydroxyimino) methyl)‐pyridinium dibromide), (55,98 μmol/kg) in mice was investigated. The concentrations of oximes in plasma determined by high pressure liquid chromatography (HPLC) corresponded to a two‐compartment pharmacokinetic open model. The oximes were rapidly eliminated from mice plasma, with half‐times of 57.93 min. for HI‐6 and 108.08 min. for trimedoxime. Although the oximes passed from circulation into the tissues at approximately the same rate, their transport back to the central compartment was two‐times slower in the case of trimedoxime: t1/2k21 was 77.9 min. for trimedoxime and 41.7 min. for HI‐6. The total body clearance (CItot) of HI‐6 was about 25% higher than that of trimedoxime. The central compartment volume of HI‐6 distribution (V1) was greater, whereas the volume of distribution of the peripheral compartment (V2) was lower for about 35% with respect to the corresponding parameters of trimedoxime. The calculated pharmacokinetic parameters for the oxime HI‐6 and trimedoxime show that trimedoxime is eliminated more slowly in mice, and penetrates better into the peripheral comparment where it remains longer.
Chronic Effect of Aluminium Ingestion on Bone in Calcium‐Deficient Rats
Authors: Konishi Yuko , Yagyu Kenichi , Kinebuchi Hideo , Saito Noboru , Yamaguchi Takuya , Ohtsuki And Yuji
Published: March 2009

Abstract: In order to elucidate the relationship of osteogenesis with aluminum and iron deposition, we investigated the histopathological findings of bone in calcium and/or aluminium‐deficient rats, together with levels of calcium, aluminium and iron in sera and bone tissues, and also the level of serum parathyroid hormone. Four week old male STD‐Wistar rats were divided into four groups to examine the effects of four kinds of diets for ten weeks. The rats on normal diet (Group I) and normal diet+aluminum (Group II) did not show any pathological changes of the bones, but in both calcium‐deficient diet group (Group III) and calcium deficient diet added aluminium (Group IV), the compact bone converted into spongy bone in varying degrees, paticularly in Group IV. Aluminium deposition was demonstrated at the calcification fronts and the cement lines only in Group IV as red or violet‐red lines with aluminium stain, together with iron deposition as revealed with Berlin blue stain, showing similar distribution pattern as aluminum. It was clearly indicated that aluminium and iron, instead of calcium, deposited on the calcification front of the bone under the condition of calcium deficiency, inhibiting the normal osteogenesis.
Inhibition of Cell‐Cell Communication by Commercial Chlorinated Paraffins in Rat Liver Epithelial IAR 20 Cells
Authors: Kato Yoshihisa , Kenne Kerstin
Published: March 2009

Abstract: The effects of six commercial chlorinated paraffins of different carbon chain length and chlorine content (Cereclor 50LV [C50LV], Hüls 60 [H60], Cereclor S45 [CS45], Cereclor S52 [CS52], Cereclor 42 [C42] and Cereclor 48 [C48] on cell communication have been investigated in the scrape‐loading/dye‐transfer assay in IAR 20 rat liver epithelial cells, as well as the effects of these compounds on connexin 43 (cx 43), the main gap junction protein in this cell line. The results clearly demonstrated that at non‐cytotoxic concentrations C50LV, H60, CS45 and CS52 completely inhibited the cell communication within 1 hr. The short carbon chain length chlorinated paraffins (C50LV and H60) were inhibiting the cell communication at lower concentration than the intermediate carbon chain length chlorinated paraffins (CS45 and CS52). Almost complete inhibition of the cell communication was maintained for at least 24 hrs of H60 exposure. Immunoblots of IAR 20 cell extracts after H60‐exposure showed a decreased phosphorylation of cx 43 after 1, 4 and 24 hrs of treatment. The phosphorylation pattern of cx 43 prepared from H60‐ or CS52‐exposed cells was different from that prepared from 12‐O‐tetradecanoylphobol‐13‐acetate (TPA)‐exposed cells after 1 hr treatment. The results show that the short and intermediate, but not the long carbon chain length chlorinated paraffins, are potent inhibitors of gap junction intercellular communication. Thus, our findings suggest that these compounds may act as tumour promoters.
Lysosomal Storage of Sulphated Glycosaminoglycans Induced by Dicationic Amphiphilic Drug molecules: Significance of the Central Planar Ring System
Authors: Lüllmann‐Rauch Renate , von Witzendorff Burkhard
Published: March 2009

Abstract: The immunomodulatory drug tilorone (2,7‐bis[2‐(diethylamino)ethoxy]fluoren‐9‐one) and several congeners are known to disturb the lysosomal degradation of sulphated glycosaminoglycans and thereby induce lysosomal storage of glycosaminoglycans in cultured cells and intact organisms. The molecules of tilorone and congeners consist of a planar aromatic ring system symmetrically substituted with two aliphatic side chains each carrying a protonizable nitrogen. In a previous study it was proposed that non‐degradable glycosaminoglycan‐drug complexes are formed by electrostatic interactions and that additionally intermolecular interactions between the drug molecules due to electronic coupling of their central planar ring system are important for formation and stabilization of the glycosaminoglycan‐drug complexes and thus for the drug side effect in question. The significance of the central planar ring system was tested in the present study by comparing tilorone and the compound bis(β‐diethylamino‐ethylether)hexestrol (DH) with respect to their potencies to cause lysosomal glycosaminoglycan storage in cultured bovine corneal fibroblasts. DH has the same side chains as tilorone, but its central apolar moiety lacks planarity. At a concentration (1.75 μM) which did not cause enhanced secretion of the lysosomal enzyme β‐hexosaminidase (E.C. 3.2.1.52), DH was significantly less potent than tilorone in causing storage of [35S]glycosaminoglycans. This is taken as support of the hypothesis that the planar tricyclic ring system is essential for the high potency of tilorone and its congeners to exert this adverse action.
Ethanol Interference with Morphine Metabolism in Isolated Guinea Pig Hepatocytes
Authors: Aasmundstad Tor A. , Lillekjendlie Bjørn , Mørland Jørg
Published: March 2009

Abstract:It has previously been shown that guinea pig hepatocytes metabolise morphine in a fashion similar to humans. The metabolism of morphine (5 μM) and the formation of metabolites morphine‐3‐glucuronide, morphine‐6‐glucuronide and normorphine was studied in the absence and presence of ethanol (5, 10, 25, 60 and 100 mM) in freshly isolated guinea pig hepatocytes. In order to gain more detailed information, a mathematical model was estimated on experimental data and used to analyse the effects of ehtanol on the reaction rates of the different morphine metabolites. Ethanol inhibited the rate of morphine elimination in a dose‐related manner, at the high ethanol concentrations the elimination rate was 40 per cent of the control rate. The formation of morhine‐glucuronides was influenced in a biphasic manner. Five and 10 mM ethanol increased both the morphine‐3‐glucuronide and morphine‐6‐glucuronide levels after 60 min incubation compared to the control, whereas at the higher ethanol concentrations (25‐100 mM) the levels of morphine‐glucuronides were reduced. Data from the mathematical model, however, demonstrated that the reaction rates for morphine‐glucuronide formation were decreased at all ethanol concentrations and in a dose‐dependent manner, the interpretation of this being that at the lower (5 and 10 mM) ethanol concentraions employed in this study, other metabolic pathways of morphine are more heavily inhibited than the glucuronidations, resulting in a shunting towards morphine‐3‐glucuronide and morphine‐6‐glucuronide. The pharmacodynamic consequences of these pharmacokinetic effects are thus somewhat diffucult to predict since morphine‐6‐glucuronide has a higher agonist potency than morphine. At high concentrations ethanol inhibition of morphine metabolism will increase the concentration of morphine and subsequently the euphoric and the toxic effects. The lower quantities of morphine‐6‐glucuronide formed in the presence of high ethanol concentrations on the other hand most probably imply reduction of such effects and the net pharmacodynamic effect would be uncertain. At low ethanol concentrations, however, morphine‐6‐glucuronide concentrations increased and morphine metabolism was less inhibited leading to a possible potentiation of the effects of morphine. Thus, a low ehtanol concentration might exert a more pronounced ethanol‐drug effect interaction than a higher ethanol concentration.
Eliprodil Prevents Expression of the 70 kDa Heat Shock Protein in MK801‐Injured Neurones
Authors: Wang Shu , Yang Qiner , Moller Claus J. , Sharp Frank R. , Haglid Kenneth G.
Published: March 2009

Abstract:The present study examined whether eliprodil (SL 82.0715), an N‐methyl‐D‐aspartate (NMDA) receptor antagonist acting on the polyamine sites induced expression of the 70 kDa heat shock protein (HSP70) in the rat brain. Whereas the NMDA channel blocker MK801 consistently induced HSP70 in posterior cingulate and retrosplenial cortices, eliprodil had no such effects even at the highest dose (50 mg/kg, intraperitoneally), supporting the idea that injury to the cerebrocortical neurones by NMDA receptor antagonists is probably related to specific sites of the receptor. Furthermore, eliprodil, given immediately after injection of MK801, blocked the effects of MK801 on HSP70. The result is discussed in terms of high affinity of eliprodil for the σ receptor.
Itraconazole Increases Serum Digoxin Concentration
Authors: Partanen Juhani , Jalava Kirsi‐Maija , Neuvonen Pertti J.
Published: March 2009

Abstract: Itraconazole can interact with several drugs by inhibiting their metabolism. Many drugs known to increase serum digoxin concentration are inhibitors of CYP enzymes (e.g. verapamil, diltiazem, amiodarone, cyclosporine). Case reports suggest that itraconazole, added to digoxin therapy, may induce digoxin intoxications; hence we wanted to study their possible interaction. In this two‐phase study ten healthy young volunteers ingested 0.25 mg of digoxin daily for 20 days. Concomitantly, they received either 200 mg itraconazole or placebo orally once daily for 10 days in a double‐blind, randomized, cross‐over study design. Serum concentrations of digoxin and itraconazole were measured (12 hr after administration) on days 1, 2, 4, 6, 8, 10, 11, 12, 14, 16, 18 and 20. Digoxin concentrations were measured by fluorescence polarization immunoassay and confirmed (days 10 and 20) by affinity column‐mediated immunoassay. Itraconazole increased serum digoxin concentration in each of the subjects. On the 10th day of the placebo phase serum digoxin concentration was 1.0±0.1 nmol/1, and on the 10th day of the itraconazole phase 1.8±0.1 nmol/1 (P<0.001). Care should be taken if itraconazole is prescribed to patients using digoxin. The mechanism of the itraconazole‐digoxin interaction is unclear but may be related to CYP3A4‐mediated changes in the pharmacokinetics of digoxin.
5‐HT3Receptor Antagonist MDL 72222 Dose‐Dependently Attenuates Cocaine‐ and Amphetamine‐Induced Elevations of Extracellular Dopamine in the Nucleus Accumbens and the Dorsal Striatum
Authors: Kankaanpää Aino , Lillsunde Pirjo , Ruotsalainen Minna , Ahtee Liisa , Seppälä Timo
Published: March 2009

Abstract:The effects of a 5‐HT3receptor antagonist MDL 72222 on cocaine‐ and amphetamine‐induced increases in extracellular dopamine in the nucleus accumbens and the dorsal striatum were studied with microdialysis technique using halothane anaesthesized rats. Dopamine and its metabolites were measured by HPLC with electrochemical detection. Cocaine elevated extracellular dopamine in the nucleus accumbens and to a lesser extent in the dorsal striatum, but it did not affect dopamine metabolites,3,4‐dihydroxyphenylacetic acid (DOPAC) and homovanillic acid. Pretreatment with MDL 72222 (25‐100 μg/kg) dose‐dependently attenuated cocaine‐induced elevation of dopamine in both of the nuclei studied. Amphetamine elevated extracellular dopamine and reduced DOPAC and homovanillic acid equally in the nucleus accumbens and in the dorsal striatum. MDL 72222 also attenuated the amphetamine‐induced elevation of extracellular dopamine concentration in both brain areas studied, but first at a dose of 100 μg/kg. The different potencies of the interactions of the 5‐HT3receptor antagonist with cocaine and amphetamine could be related to the different mechanisms by which these drugs primarily elevate extracellular dopamine.
Capsaicin‐, Resiniferatoxin‐, and Lactic Acid‐Evoked Vascular Effects in the Pig Nasal Mucosain vivowith Reference to Characterization of the Vanilloid Receptor
Authors: Rinder JoHan , Szallasi Arpad , Lundberg Jan M.
Published: March 2009

Abstract:Nasal cavity volume, mucosal and superficial skin blood flow as well as renal splenic vascular effects of capsaicin, resiniferatoxin and lactic acid were investigated, using a novelin vivopig model. The present results show that locally intraarterially injected capsaicin, resiniferatoxin and lactic acid evoke similar vasodilatory responses, although with different duration, in the nasal mucosa and superficial skin as well as an increase in heart rate and mean arterial blood pressure. Nasal vascular responses evoked by capsaicin, resiniferatoxin and lactic acid were unaffected by the cyclooxygenase inhibitor diclofenac. Moreover, chlorisondamine did not alter the nasal vasodilatory responses evoked by capsaicin and lactic acid. However, chlorisondamine abolished sympathetic reflex‐mediated vasoconstrictor effects of capsaicin in the spleen and kidney. Lactic acid‐evoked vasodilation in the nasal mucosa and skin was inhibited by the 8‐37 fragment of calcitonin gene‐related peptide, a calcitonin gene‐related peptide‐receptor antagonist. Lactic acid‐evoked vasoconstriction in the spleen and kidney was reduced but not abolished by chlorisondamine, suggesting that the effects of lactic acid are not exclusively reflex‐mediated. Capsazepine did not inhibit the vasodilatation in the nasal mucosa evoked by capsaicin and lactic acid. [3H]Resiniferatoxin bound to pig nasal mucosa membranes with an affinity of 134 pM in a non‐cooperative fashion; this binding behaviour contrasted to the apparent positive cooperativity (a Hill coefficient of 2.2) of specific resiniferatoxin binding to pig spinal cord preparations. Specific [3H]resiniferatoxin binding to nasal mucosa membranes was fully inhibited by capsaicin (Ki= 5 μM) and lactic acid (IC50at pH 5.0) but not by capsazepine (up to 10 μM), in accord with the physiological findings. Capsazepine, by contrast, displaced [3H]resiniferatoxin from spinal vanilloid receptors with an affinity of 3 μM. These findings show the presence of vanilloid receptors in the pig nasal mucosa and suggest heterogeneity in the properties of vanilloid receptors in the pig. Furthermore, lactic acid evokes vascular effects similar to those of capsaicin and resiniferatoxin, possibly via interaction of protons and/or proton‐generated substances at vanilloid receptors with a subsequent release of calcitonin gene‐related peptide.
Cardiovascular Actions of Chronic Intracerebroventricular Administration of Metformin in Normotensive Rats
Authors: Andersen Ditte , Haugan Ketil , Sørensen Anne‐Mette , Christensen Sten , Petersen Jøryen Søberg
Published: March 2009

Abstract:Acute intracerebroventricular administration of the antihyperglycaemic agent metformin (0.25–1 mg) elicits sympathoinhibitory responses in spontaneously hypertensive rats. However, cardiovascular actions of chronic intracerebroventricular metformin administration are unknown. To define the dose‐response relationship during chronic intracerebroventricular metformin administration, mean arterial pressure, heart rate, and locomotor activity were measured continuously by radiotelemetry in 40 normotensive rats. After a 10 day control period, an intracerebroventricular cannula was implanted and connected to an osmotic minipump which delivered metformin in the following doses: 0 [saline], 0.01, 0.1, 1, and 10 mg/day. LD50was 1.5 mg/day. Metformin, 1 mg/day attenuated the nocturnal, physiological increase in mean arterial pressure (‐7.3+1.6% versus before metformin), produced behavioural changes and tended to increase locomotor activity. Lower doses of intracerebroventricular metformin (0.1 and 0.01 mg/day) did not affect mean arterial pressure, heart rate or locomotor activity. In conclusion, chronic intracerebroventricular administration of high dose metformin (1.0 mg/day) attenuates the nocturnal, physiological increase in mean arterial pressure. These findings are compatible with a toxic, sympathoinhibitory action of high doses of metformin intracerebroventricularly.
Stretch‐Induced Stimulation of Lower Airway Nitric Oxide Formation in the Guinea‐Pig: Inhibition by Gadolinium Chloride
Authors: Bannenberg Gerard L. , Gustafsson Lars E.
Published: March 2009

Abstract: The effect of stretch on lower airway nitric oxide formation was studied in normoxic tracheostomized anaesthetized guinea‐pigs. Increase of level of positive end‐expiratory pressure caused increased lower airway nitric oxide formation, as measured by its presence in exhaled tracheal air. The L‐type calcium channel blocker, verapamil, did not decrease lower airway nitric oxide formation. Neither the local anaesthetic xylocaine nor the ganglion blocker trimetaphan affected exhaled nitric oxide, excluding local and centrally‐mediated neuronal reflexes. Intravenous administration of gadolinium chloride (GdCl3, 50 mg/kg) induced a rapid and pronounced decrease (75%) in the basal level of exhaled nitric oxide. GdCl3 completely abolished lower airway nitric oxide formation induced by ventilation with positive end‐expiratory pressure (7 cm H2O). GdCl3 induced hypoxaemia, but there was no indication for the development of lung oedema. The results indicate that positive end‐expiratory pressure stimulates lower airway nitric oxide formation in the guinea‐pig. GdCl3 inhibits lower airway nitric oxide formation in the guinea‐pig in vivo, perhaps by interference with stretch‐induced cellular calcium‐influx.
Cholecystokinin‐B/Gastrin Receptor Blockade Suppresses the Activity of Rat Stomach ECL Cells
Authors: Ding Xi‐Qin , Lindström Erik , Håkanson Rolf
Published: March 2009

Abstract:Gastrin controls the histamine‐ and chromogranin A‐ producing enterochromaffinn‐like (ECL) cells, the predominant endocrine cell population in the acid‐producing part of the rat stomach. They are responsible for most of the circulating pancreastatin, a chromogranin A‐derived peptide. The present study examines the ability of two potent and highly selective cholecystokinin‐B/gastrin receptor antagonists. RP73870 and YM022, to incapacitate the ECL cells. The two antagonists were given by continuous subcutaneous infusion to otherwise untreated rats and to hypergastrinaemic rats treated with gastrin‐17 (continuous subcutaneous infusion) or omeprazole (orally) for 7 days. Several parameters reflecting ECL cell activity were measured: The oxyntic mucosal histidine decarboxylase activity, the histamine concentration, the histidine decarboxylase mRNA and chromogranin A mRNA concentrations, and the serum pancreastatin concentration. In addition, the serum gastrin concentration was measured. RP73870 and YM022 greatly lowered the oxyntic mucosal histidine decarboxylase activity and the histidine decarboxylase mRNA and chromogranin A mRNA concentrations, and also reduced the oxyntic mucosal histamine concentration and the serum pancreastatin concentration. Moreover, they raised the serum gastrin concentration. With respect to blockade of histidine decarboxylase activity, 1.0 μmol· g−1· hr−1was an almost maximally effective dose for both RP73870 and YM022. The corresponding ID50values were 0.04 and 0.05 μmol‐ kg−1· hr−1. RP73870 and YM022 inhibited the hypergastrinaemia‐evoked rise in all ECL‐cell parameters. The results suggest that sustained cholecystokinin‐B/gastrin receptor blockade causes lasting deactivation of the ECL cells.
Accumulation of Nicotine in Human Hair during Long‐Term Controlled Exposure to a Low Concentration of Nicotine Vapour
Authors: Nilsen Turid , Nilsen Odd G.
Published: March 2009

Abstract: Hair from 5 subjects were exposed in dynamic exposure chambers to air nicotine vapour for 72 hr or 12 months at concentrations of 200 or 5μg/m3, respectively. Nicotine in the chamber air and human hair was determined by GC/ MS. A linear accumulation of nicotine in hair was found with time for all hairs during the long‐term, low concentration exposure, with individual hair nicotine uptake rate constants ranging from 0.70 to 3.75×10−3 m3/gxhr. The corresponding hair nicotine uptake rate constants during short‐term, high concentration exposure, were significantly higher, ranging from 1.35 to 15.11×10−3 m3/gxhr, showing, however, a highly significant linear correlation with the individual long‐term exposure rate constants, r2=0.9961. It is indicated that long‐term hair nicotine uptake rate constants calculated from controlled exposure experiments with pure nicotine vapour are adequate for estimation of individual long‐term hair accumulation of nicotine from environmental tobacco smoke even at variable and intermittent exposure. Although higher than the long‐term uptake rate constants, the short‐term uptake rate constants seem well fitted for a differentiation between different types of hair in their ability to adsorb nicotine also during long‐term exposures. The short‐term uptake rate constants might also be useful parameters for establishing a reliable cut‐off limit in the hair concentration of nicotine between smokers and non‐smokers which otherwise seems to be overlapping.
In vitro Toxicity of Cobalt and Hard Metal Dust in Rat and Human Type II Pneumocytes
Authors: Roesems G. , Hoet P. H. M. , Demedts M. , Nemery B.
Published: March 2009

Abstract: It has been demonstrated that hard metal dust, which consists of a mixture of cobalt and tungsten carbide, is more toxic toward mouse peritoneal and rat alveolar macrophages than pure cobalt (Co) or tungsten carbide (WC). The aim of this study was to investigate the toxic effects of Co and hard metal dust on alveolar epithelial type II cells (AT‐II), and to compare these with alveolar macrophages. Freshly isolated rat and human AT‐II and rat alveolar macrophages were exposed for 18 hr to particles of Co, WC or Co/WC. As an index for cell toxicity, release of lactate dehydrogenase was measured. For rat AT‐II, TD50 values per 105 cells were 672 μg (95% C.I. = 264‐1706 μg) for pure Co and 101 μg (95% C.I. = 59‐172 μg) for Co in Co/WC mixture. For rat alveolar macrophages, TD50 values per 105 cells were 18 μg (95% C.I.=15‐24 μg) for pure Co and 5 μg (95% C.I. = 5‐6 μg) for Co in Co/WC mixture. WC only caused an increase in lactate dehydrogenase at high concentrations. No toxicity was found in human AT‐II for either Co, WC or Co/WC. These results indicate that 1) rat AT‐II are less sensitive to Co than rat alveolar macrophages, 2) human AT‐II are less sensitive to Co than rat AT‐II, 3) the toxicity of Co is increased by the presence of WC.
Effects of Lead Exposure on Bromocriptine‐Induced Penile Erection in Rats
Authors: Ghazi‐Khansari Mahmoud , Heidari Ismaeel , Zarrindast Mohammad‐Reza
Published: March 2009

Abstract: In the present work we have studied the effects of lead exposure on penile erection induced by bromocriptine. Intraperitoneal injection of bromocriptine (2, 3, 4 and 8 mg/kg) induced dose‐related penile erection in rats. Maximum response was observed with 4 mg/kg of the drug. Lead exposure (as Pb‐acetate in drinking water) for periods of 7, 14, 21 and 28 days decreased the bromocriptine‐induced penile erection response. Higher concentrations of lead (0.05%) were shown to cause a more prominent decrease of penile erection. The same procedure for lead administration did not significantly alter penile erection induced by physostigmine (0.1 and 0.3 mg/kg, intraperitoneally). In a series of experiments, blood lead concentrations were measured 7 and 21 days after lead exposure. Significant increases of lead concentrations were found after lead exposure. It is concluded that lead can influence bromocriptine‐induced penile erection.
The Efficacy of Monopyridinium (2‐PAAM, 2‐PAEM) and Bispyridinium (Obidoxime, HI‐6) Oximes against Mevinphos in Mice
Authors: Kassa Jiří , Bielavský Jiří
Published: March 2009

Abstract: The efficacy of two new monopyridinium oximes (2‐PAAM, 2‐PAEM) and two bispyridinium oximes (obidoxime. HI‐6) was tested in combination with atropine sulphate against acute poisoning with the organophosphorus insecticide mevinphos in mice. When mice were treated two min. after mevinphos poisoning, no significant differences in the therapeutic effect of tested oximes were observed. The oximes increased the 24 hr LD50 values of mevinphos about two times in comparison with the 24 hr LD50 values of mevinphos in mice protected with atropine sulphate alone and more than three times in comparison with non‐treated intoxicated animals. On the other hand, both monopyridinium oximes were significantly more efficacious than HI‐6 and as efficacious as obidoxime when they were administered 30 sec. after mevinphos poisoning. Both monopyridinium oximes and obidoxime increased the 24 hr values of mevinphos almost three times in comparison with the 24 hr values of mevinphos in mice protected with atropine sulphate alone and about twenty‐five times in comparison with non‐treated intoxicated animals, while the oxime HI‐6 less than two times in comparison with the 24 hr values of mevinphos in mice protected with atropine sulphate alone and about fifteen times in comparison with non‐treated intoxicated animals. (change‐para‐here) Use of new monopyridinium oximes seems to be the improvement in the antidotal treatment of poisoning with organophosphorus insecticide mevinphos in comparison with HI‐6 but not in comparison with obidoxime when oximes are used in equimolar doses.
Effects of 3‐Deazaadenosine on Apoptosis‐Related Gene Transcripts in HL‐60 Cells
Authors: Loennechen Thrina , Moens Ugo , Kildalsen Hanne , Andersen Anders , Rekvig Ole Petter , Aarbakke Jarle
Published: March 2009

Abstract:The effect of the transmethylation inhibitor 3‐deazaadenosine on transcription levels of genes associated with apoptosis was investigated in HL‐60 cells. After incubation of HL‐60 cells with 100 μM 3‐deazaadenosine for 45 min., a schedule known to perturb transmethylation metabolites and initiate apoptosis in these cells, a 50% decrease inc‐mycand a 50% increase inbcl‐2RNA steady‐state levels compared to control cells were observed. Transcription levels ofc‐myccontinued to decrease after extended exposure to 3‐deazaadenosine, whilebcl‐2mRNA levels dropped to 25% and 30% below those in control cells after 1.5 hr and 3 hr, respectively. The expression levels of thebcl‐2relatedbaxgene, showed a similar pattern asbcl‐2;a 60% increase was initially measured, but after 1.5 and 3 hr,baxtranscripts were 80% and 70% respectively, of those found in untreated cells. Anotherbcl‐2related gene,bcl‐x, was previously reported to generate two transcripts in human cells. The long variantbcl‐x1acts asbcl‐2, while the short formbcl‐xsinduces apoptosis. We were unable to detectbcl‐xstranscripts in untreated and 3‐deazaadenosine treated cells by the highly sensitive reverse transcriptase polymerase chain reaction method. This suggests that this gene product may not be involved in 3‐deazaadenosine induced apoptosis in HL‐60 cells.Bcl‐x1mRNA levels, however, slowly decreased with about 50% after 1.5 or 3 hr 3‐deazaadenosine treatment. It is concluded that 3‐deazaadenosine initiated apoptosis affectsc‐myc, bcl‐2, baxandbcl‐x1mRNA levels.
Analysis of Native Human Plasma Proteins and Haemoglobin for the Presence of Bityrosine by High‐Performance Liquid Chromatography
Authors: Daneshvar Bahrain , Frandsen Henrik , Dragsted Lars O. , Knudsen Lisbeth E. , Autrup Herman
Published: March 2009

Abstract: Generation of reactive oxygen species in vivo results in oxidative‐damage to cellular components, including proteins. Due to the relatively long half‐lives of several blood proteins the cumulative formation of oxidatively damaged proteins might serve as a biomarker for reactive oxygen species formation. The most prominent sources of reactive oxygen species in vivo are site‐specific metal ion‐catalyzed reactions of the Fenton and Haber‐Weiss types and the H2O2/peroxidase system. In vitro oxidation of L‐tyrosine using a peroxidase or Cu++/H2O2 system gives rise to the formation of a highly fluorescent substance, bityrosine. High‐performance liquid chromatography (HPLC) analysis of acid hydrolyzed serum albumin after oxidation with peroxidase/ H2O2 or with Cu++/H2O2 showed that bityrosine had been formed whereas oxidation of this protein with Fe(III)/ ascorbate did not result in the formation of bityrosine. Bityrosine could not be detected in human plasma proteins or haemoglobin with the detection limit of one pmol per mg protein.
Modulation by the Endothelium of the Inhibitory Effects of Pinacidil and Nimodipine on Endothelin‐Induced Contraction in Cerebral Arteries
Authors: Petersson Jesper , Andersson Karl‐Erik , Brandt Lennart , Högestätt Edward D.
Published: March 2009

Abstract:The effects of pinacidil and nimodipine on endothelin‐1‐induced contractions in isolated cerebral arteries with and without endothelium were compared. The sensitivity to endothelin‐1 was increased (0.5 log units) in the rabbit basilar artery after removal of the endothelium. The nitric oxide synthase inhibitor Nω‐nitro‐L‐arginine (0.1 mM) also increased the sensitivity to endothelin‐1 (0.6 log units) in basilar arteries with endothelium, whereas Nω‐nitro‐D‐arginine (0.1 mM) and indomethacin (3 μM) had no effect, indicating that withdrawal of endothelium‐derived nitric oxide may account for the enhancement of the endothelin‐1‐induced contraction after endothelial denudation. Pinacidil (1 μM) shifted the concentration‐response curve for endothelin‐1 to the right without affecting the maximal response in arteries without endothelium, but had no effect on the endothelin‐1‐induced contraction in vessels with endothelium. Nimodipine (1 μM) reduced the maximal endothelin‐1‐induced contraction by approximately 50% in both the presence and absence of endothelium, whereas the sensitivity to endothelin‐1 was reduced only in vessels without endothelium. Incubation in "calcium‐free" medium reduced the maximal endothelin‐1‐induced contraction by 69% and 80% in vessels with and without endothelium, respectively. In human pial arteries with endothelium, pinacidil did not affect the endothelin‐1‐induced contraction, whereas nimodipine and exposure to "calcium‐free" solution reduced the maximal response by 31% and 74%, respectively. The results show that, in the rabbit, pinacidil and to a lesser extent nimodipine preferentially act on cerebral arteries with disrupted endothelium, indicating that vasoactive factors liberated from the endothelium may modify the effect of a vasodilator.
Inotropic Response of Rat Heart Papillary Muscle to α1‐and β‐Adrenoceptor Stimulation in Relation to Dietary n‐6 and n‐3 Polyunsaturated Fatty Acids (PUFA) and Age
Authors: Skúladóttir Gudrún V. , Jóhannsson Magnús
Published: March 2009

Abstract:The effect of dietary n‐6 and n‐3 polyunsaturated fatty acids (PUFA) and age on inotropic responses of heart papillary muscle to α1‐or β‐adrenoceptor stimulation was examined in young (4 months), middle‐aged (12 months) and senescent (27 months) male Wistar rats. From the age of two months the rats were fed a diet containing 2% or 12% of fat by weight varying in PUFA type: a) standard low‐fat n‐6 PUFA diet, b) high‐fat n‐6 PUFA diet or c) high‐fat n‐3 PUFA diet. The inotropic responses to α1‐adrenoceptor stimulation with phenylephrine were triphasic (positive, negative, then positive). Young, high‐fat n‐3 PUFA‐fed rats exhibited significantly lower negative and higher positive responses to phenylephrine stimulation, and higher positive responses to isoprenaline stimulation than young, high‐fat n‐6 PUFA‐fed rats. On the other hand, no such dietary‐related difference was found between young rats fed a high‐fat n‐3 PUFA diet and a standard low‐fat n‐6 PUFA diet. The young high‐fat n‐6 PUFA‐fed rats exhibited inotropic responses similar to those of the middle‐aged and senescent rats within the three dietary groups. The time to peak force and the time of half relaxation did not differ within dietary and age groups. The findings indicate that dietary n‐6 PUFA‐rich supplementation at a young age induces changes resembling the effects of age, as evidenced by decreasing cardiac responses to adrenoceptor agonists, such as phenylephrine or isoprenaline.
Ibuprofen Inhibits the Metabolism of the Endogenous Cannabimimetic Agent Anandamide
Authors: Fowler Christopher J. , Stenström Anders , Tiger Gunnar
Published: March 2009

Abstract:A measure of the metabolism of anandamide, an endogenous cannabimimetic agent, by rat cerebellar membrane preparations was obtained by following the time‐dependent reduction in potency of this compound towards inhibition of binding of the high‐affinity cannabinoid agonist ligand [3H]WIN 55212‐2 to cannabinoid receptors. Thus for example, incubation of the membranes with 100 nM anandamide for 0, 10 and 30 min. prior to addition of [3H]WIN 55212‐2 and phenylmethylsulphonyl fluoride (to inhibit the activity of anandamide amidase, thereby blocking further anandamide metabolism during the binding assay) produced 57±3, 38±5 and 19±7% inhibition, respectively, of [3H]WIN 55212‐2 binding. This time‐dependent effect was blocked by ibuprofen but not by acetyl salicylic acid, sulindac, acetaminophen or to any significant extent by ketoprofen and naproxen. Preliminary experiments using a direct assay of anandamide amidase with [14C]anandamide as ligand gave an IC50value for ibuprofen of ∼400 μM. The potency of ibuprofen as an inhibitor of anandamide metabolism was of the same order of magnitude as required for inhibition of cyclooxygenase‐2 in cell‐free systems and of the peak plasma concentrations of this drug following a 2x200 mg dose regimen. It is concluded that following therapeutic doses of ibuprofen, the metabolism of anandamide may be affected.
Age Might Influence the Frequency Distribution of Metoprolol Hydroxylation Polymorphism in a Chinese Population
Authors: Wan Jie , Xie Yan‐Hong , Xia Hui , Lu Yi‐Qing
Published: March 2009

Abstract: The frequency distribution of the 8‐hour urinary ratio of metoprolol/α‐hydroxymetoprolol (MR) was investigated in 206 healthy rural Chinese volunteers. The frequency of the poor metabolizer phenotype of metoprolol α‐hydroxylation was 0% in this Chinese population. When the 206 subjects were subgrouped into four groups by age, the excretion of α‐hydroxymetoprolol was significantly lower in the subjects with age older than 41 years compared to two younger groups (16–30 years), and the metoprolol hydroxylation metabolic ratio(metoprolol/a‐hydroxymetoprolol, MR) was higher in these middle‐aged subjects, indicating that age may affect the frequency distribution of the 8‐hour urinary MR or log MR, although multiple regression analysis did not show a significant correlation between age, urine volume and MR. Also, a significant correlation was found between age and the excretion (percentage of dose) of α‐hydroxymetoprolol in 8‐hour urine (r= −0.259, P<0.001). On the other hand, both multiple regression analysis and nonparametric tests showed that the larger the amount of urine excreted, the more metoprolol was recovered, demonstrating that the urinary excretion of unchanged metoprolol is renal flow‐limited.
Effects of Mercuric Chloride and Methyl Mercury on Cholinergic Neuromuscular Transmission in the Guinea‐Pig Ileum
Authors: Candura Stefano M. , D'Agostino Gianluigi , Castoldi Anna F. , Messori Eliana , Liuzzi Maddalena , Manzo Luigi , Tonini Marcello
Published: March 2009

Abstract:The effects of mercuric chloride (HgCl2) and methyl mercury (MeHg) were examined on basal mechanical activity and electrically‐induced neurogenic cholinergic contractions (twitch contractions) in longitudinal muscle‐myenteric plexus strips from guinea‐pig distal ileum. Both compounds at 0.3‐3 μM slightly enhanced the amplitude of twitch contractions in ~50% preparations. This effect was probably due to facilitation of acetylcholine (ACh) release since 0.1 and 1 μM mercurials increased electrically‐evoked tritium outflow from [3H]choline preloaded muscle layer with attached myenteric plexus. Conversely, higher mercury concentrations inhibited twitch contractions (HgCl2IC50=21.3±6.4 μM; MeHg IC50=45.1±5.5 μM), as well as contractions to exogenous ACh (0.1 μM) in resting preparations, and concomitantly increased the basal tone. The former effects possibly reflected an antimuscarinic activity of mercury, while the latter was related to alterations of calcium homeostasis in the effector cells. Indeed, the effect of HgCl2on basal tone was antagonized by the Ca2+entry blocker nifedipine (3, 10, 30 nM), indicating Hg‐induced facilitation of Ca2+influx through voltage‐dependent channels. On the whole, our results suggest that cholinergic neuromuscular transmission and Ca2+‐dependent mechanisms underlying smooth muscle contractility are targets for mercury toxicity in the intestine.
Comparative Study on the Effect of Calcium Channel Blockers on Basal and Parathyroid Hormone‐Induced Bone Resorptionin vitro
Authors: Redlich K. , Pietschmann Peter , Štulc T. , Peterlik M.
Published: March 2009

Abstract:A number of clinical and experimental studies suggest that the effects of calcium channel blockers are not limited to the cardiovascular system but might also involve skeletal calcium metabolism due to the presence of L‐type calcium channels in osteoblastic cells. We therefore investigated the influence of calcium channel blockers of the dihydropyridine type (nifedipine, amlodipine) as well as of the phenylalkylamine type (verapamil, gallopamil) on basal and parathyroid hormone‐induced bone resorption utilizing organ‐cultured neonatal mouse calvaria. Only at 10‐4M, amlodipine, verapamil and gallopamil reduced basal and parathyroid hormone‐induced resorption In contrast, nifedipine, between 10‐6–10‐4M, exhibited a dose‐dependent inhibitory effect on parathyroid hormone‐related bone resorption by up to 50%. When calvariae were cultured for 48 hr in the presence of inhibitory concentrations of the calcium channel blockers and then stimulated with parathyroid hormone, only parietal bones pretreated with nifedipine remained completely responsive to the bone resorbing action of the hormone.