bluuebunny/crossref_metadata_2025 huggingface dataset:
The Mauve Factor of Porphyria, 3‐Ethyl‐5‐hydroxy‐4,5‐dimethyl‐delta‐3‐pyrroline‐2‐one: Effects on Behaviour of Rats and Mice
Authors: Cutler Margaret G. , Graham Douglas J. M. , Moore Michael R.
Published: March 2009

The monopyrrole, 3‐ethyl‐5‐hydroxy‐4,5‐dimethyl‐delta3‐pyrroline‐2‐one (HPL), was given by intraperitoneal injection to rats (0.65 mmol/kg) and to mice (0.98 and 1.95 mmol/kg). Behaviour of the rats was assessed for 1.5 hr after injection by monitoring their spontaneous activity, while behaviour of the mice was examined by ethological procedures during dyadic encounters over a 5 min. period at 50‐60 min. following injection. Activity of the rats, once habituated to the cage, was reduced by HPL. No other abnormalities were discernible. In mice, HPL at 1.95 mmol/kg increased the frequency of “head twitch” and evoked a smaller increase of “backward locomotion”. There were no changes in overall agonistic, social or non‐social behaviour in the HPL treated mice. Plasma concentrations of HPL in mice treated with the highest dose level amounted to 0.3 ± 0.1 mmol/1, many‐fold above its plasma concentrations during acute porphyric attacks in man. It thus appears that in rodents HPL has slight behavioural activity, but that it is unlikely to play any significant role in the psychiatric disturbances of acute porphyria.
Pharmacokinetics of Recombinant Human Erythropoietin in Chronic Haemodialysis Patients
Authors: Nielsen Ove Juul
Published: March 2009

Single dose intravenous and subcutaneous pharmacokinetics of recombinant human erythropoietin (rhEPO) has been determined in 6 chronic haemodialysis patients. Four patients, all on maintenance therapy with rhEPO, were consecutively treated both intravenously and subcutaneously with injections of rhEPO in a dose of 50 U/kg. Two previously untreated patients received 150 U/kg of rhEPO intravenously and subcutaneously. After intravenous injection of 50 U/kg of rhEPO a mean serum half‐life value of 5.4 ± 0.9 hr was found. The corresponding half‐life after injection of 150 U/kg was 7.6 hr. The peak concentration of serum EPO after subcutaneous injection was 12.5‐20 times lower than the corresponding intravenous Cmax. After administration of 150 U/kg subcutaneously the absorption of EPO was monitored to completion at 120 hr. The complete bioavailability of subcutaneous rhEPO after injection of 150 U/kg was 31.7%. Whether this low and protracted subcutaneous absorption of rhEPO is accounted for by either impeded absorption or partial skin degradation of rhEPO is not known.
Accumulation and Turnover of Metabolites of Toluene and Xylene in Nasal Mucosa and Olfactory Bulb in the Mouse
Authors: Ghaotous Hanan , Dencker Lennart , Gabrielsson Johan , Danielsson Bengt R. G. , Bergman Kerstin
Published: March 2009

Autoradiography of male mice following inhalation of the radioactively labelled solvents, toluene, xylene, and styrene, revealed an accumulation of non‐volatile metabolites in the nasal mucosa and olfactory bulb of the brain. Since no accumulation occurred after benzene inhalation, it was assumed that the activity represented aromatic acids, which are known metabolites of these solvents. This was supported by the finding that also radioactive benzoic acid (main metabolite of toluene) and salicylic acid accumulated in the olfactory bulb. High‐performance liquid chromatography revealed that after toluene inhalation (for 1 hr), nasal mucosa and olfactory bulb contained mainly benzoic acid, with a strong accumulation in relation to blood plasma, and considerably less of its glycine conjugate, hippuric acid. After xylene inhalation, on the other hand, methyl hippuric acid dominated over the non‐conjugated metabolite, toluic acid. The results indicate a specific, possibly axonal flow‐mediated transport of aromatic acids from the nasal mucosa to the olfactory lobe of the brain. The toxicological significance of these results remains to be studied.
Distribution of Disulfiram and Its Chief Metabolites over Erythrocyte Cell Membranes and Inactivation of Erythrocyte Aldehyde Dehydrogenase Activity
Authors: Johansson Benny
Published: March 2009

The distribution of disulfiram (Antabuse®) over erythrocyte cell membranes and the inhibitory action of the parent drug and its metabolites on a disulfiram sensitive erythrocyte isozyme of aldehyde dehydrogenase (ALDH) was investigated in intact and haemolyzed human erythrocytes. These studies showed that not only disulfiram but also its bis(diethyldithiocarbamato) copper complex (Cu(DDC)2) were distributed over the erythrocyte cell membranes. In addition, disulfiram was the only substance examined that inactivated erythrocyte ALDH, a reaction which was dependent on the concentration of disulfiram added.
Functional Supersensitivity of Antinociceptive Spinal Cord α2‐Adrenoceptors, Induced by Depletion of Endogenous Noradrenaline, is Associated with an Enhanced Sensitivity for Guanine Nucleotide Regulation of3H‐Clonidine Binding
Authors: Wikberg Jarl E. S. , Post Claes
Published: March 2009

In spinal cords from normal mice,3H‐clonidine bound to α2‐adrenoceptors with an apparant Kdof 4.6 nM and capacity (Bmax) of 430 fmol/mg protein. The non‐hydrolyzable GTP analogue Gpp(NH)p was found to dose‐dependently reduce the binding of3H‐clonidine the effect of Gpp(NH)p being essentially maximal at 10‐4M. Gpp(NH)p was found to reduce the apparent affinity as well as the apparent number of binding sites for3H‐clonidine; the Kdof3H‐clonidine being 16 nM and the Bmax, 300 fmol/mg protein when 10‐4M of the nucleotide was present. In mice pretreated with the noradrenaline neurotoxin DSP4 for 14 days prior to assay, the specific binding of nearly saturating concentrations (10–30 nM) of3H‐clonidine was virtually the same as for control mice. However, for the DSP4 treated animals the down‐regulation of3H‐clonidine binding induced by 10‐4M Gpp(NH)p was significantly higher than for control mice. Thus, at a3H‐clonidine concentration of 10 nM the down‐regulation induced by Gpp(NH)p was 64.1±2.6% for the DSP4 versus 58.9±2.3% for the control mice (P<0.05). At a3H‐clonidine concentration of 30 nM the down‐regulation was 52.4±1.4% for DSP4 versus 41.8±4.1% for control mice (P<0.05). DSP4 pretreatment also potentiated the antinociceptive effect of intrathecal clonidine, as assessed by the tail‐flick and hot plate tests. It is suggested that the functional supersensitivity induced by DPS4 for clonidine is related to the increased sensitivity for guanine nucleotide regulation of the spinal cord α2‐adrenoceptors.
Inverse Relationship Between Total Glutathione S‐Transferase Content and Bile Acid Release in Isolated Hepatocytes from Untreated, Phenobarbital Pretreated and Hypothyroid Rats*
Authors: Willson R. A. , Hart J. , Hall T. , Vincent S. H.
Published: March 2009

The role of cytosolic anion binding proteins (glutathione S‐transferases) in the hepatic transport of bile acids remains controversial. To investigate whether increased levels of the hepatocyte total glutathione S‐transferase content were associated with changes in the release of bile acids from the hepatocyte, we measured the rate of release of radioactive bile acids in isolated hepatocytes from thyroidectomized, phenobarbital pretreated and untreated rats. The isolated hepatocytes were preincubated with either 14C‐cholic acid or 14C‐taurocholic acid, and the release rate of radiolabeled bile acids was determined. Hepatocyte total glutathione S‐transferase content was measured by rocket immunoelectrophoresis. The release rate of the radiolabeled bile acids was significantly (P<0.005) decreased in both hypothyroid and phenobarbital pretreated hepatocytes. The levels of total glutathione S‐transferase content were significantly (P<0.001) increased in the hepatocytes from both hypothyroid and phenobarbital pretreated animals. Our findings reveal a striking inverse relationship between the total glutathione S‐transferase content of the hepatocyte and the release rate of radiolabeled bile acids in isolated hepatocytes from two independent animal models. These observations support the hypothesis that cytosolic anion binding proteins (glutathione S‐transferases) may influence the net flux across the hepatocyte plasma membrane largely by limiting efflux.
Mechanism of Diethyldithiocarbamate‐Induced Gastric Ulcer Formation in the Rat
Authors: Ogino Keiki , Hobara Tatsuya , Kawamoto Toshihiro , Kobayashi Haruo , Iwamoto Susumu , Oka Shinji , Okazaki Yukinori
Published: March 2009

Diethyldithiocarbamate (DDC) was injected subcutaneously in the rat and the mechanism of gastric ulcer formation was investigated. DDC induced gastric ulcers in a dose‐dependent manner. DDC significantly suppressed gastric mucosal copper‐zinc superoxide dismutase (Cu, Zn‐SOD) activity at 2 hr. However, manganese‐superoxide dismutase (Mn‐SOD) activity was not changed. Gastric mucosal blood flow (GMBF) decreased to 52% of the control level at 2 hr after administration of DDC and gradually increased to reach the control level by 7 hr. A Shay rat preparation (4 hr) was used to study gastric secretion. DDC (200, 400 and 800 mg/kg) inhibited acid secretion to about 80% of the control level. Histopathological examination of the gastric mucosa after administration of DDC revealed mucosal congestive findings from 1 hr to 3 hr. These data suggested that the mechanism of DDC‐induced gastric ulcer formation may be attributable to a decreased level of GMBF and O2‐ production owing to decreased SOD activity.
Cocaine‐Induced Arrhythmia in Human Foetal Myocardium in Vitro: Possible Mechanism for Foetal Death in Utero
Authors: Richards Ira S. , Kulkarni Arun P. , Bremner William Frasier
Published: March 2009

We examined the acute in vitro effects of cocaine on cell membrane potentials and contractility of 12–16 week old human foetal heart, to better assess the potential for the induction of serious arrhythmia, in utero, by this abused substance. Ventricular preparations were maintained in a tissue bath, and continuously provided with oxygen and glucose during the measurement of membrane potentials with microelectrodes, and developed force of contractions with microforce transducers. Cocaine (600 ng/ml) had a significant effect on the ability of the heart to produce action potentials of normal rising velocity, amplitude, and duration. Within 90 min., all electromechanical activity had ceased. Under the conditions of our study, the effects of cocaine were reversible, however, reversibility in vitro may have no counterpart in utero, and irreversible loss of cardiac function may result.
κ‐Opioid Receptor Agonists Differentially Affect the Release of Neurohypophysial Hormones
Authors: Fjalland Bjarne , Christensen Jens D.
Published: March 2009

The influence of x‐opioid receptor agonists and antagonists on release of oxytocin and vasopressin was examined in isolated rat neurointermediate lobes. Electrically evoked release of oxytocin and vasopressin was concentration‐dependently inhibited by the specific x‐receptor agonist U69593, whereas bremazocine only inhibited the secretion of oxytocin markedly. Treatment with naloxone enhanced the evoked release of oxytocin significantly without effect on vasopressin secretion. The U69593‐mediated inhibition of oxytocin release was abolished by naloxone, whereas that of vasopression was unaffected. Naloxone did not reverse the bremazocine‐induced inhibition of hormone release. The data support the theory of an inhibiting endogenous control over oxytocin secretion and show that the release of oxytocin and vasopresin is differentially affected by the two K‐receptor agonists.
Disposition of Morphine‐3‐Glucuronide in the Pregnant Rhesus Monkey
Authors: Gerdin Eva , Gabrielsson Johan , Lindberg Bo , Rane Anders
Published: March 2009

Morphine‐3‐glucuronide (M3G) is the major metabolite of morphine and is present in the circulation of persons treated with morphine or abusing heroin. This project was designed to study the kinetics of M3G in the foeto‐maternal compartment, since this metabolite may be of relevance for the abstinence syndrome observed in neonates of pregnant abusers. The kinetics of M3G were studied in two non‐pregnant and four pregnant Rhesus monkeys. M3G was given as a bolus injection in four of the animals and as a long‐term infusion for 12 hr in two animals. M3G passed slowly across the placenta to the foetus and amniotic fluid. After 10 hr of M3G infusion, the foetal plasma M3G concentration was measured in two cases and found to be 37% and 72%, respectively, of the maternal concentration.
Myocardial Accumulation Kinetics and Pharmacodynamics in the Isolated Rabbit Heart of a New Inhibitor of Dopamine Reuptake, GBR 12909
Authors: Nielsen‐Kudsk Folmer , Siggaard Charlotte , Nielsen Claus Breckner , Mellemkjær Seren
Published: March 2009

Myocardial accumulation of GBR 12909 showed monophasic exponential kinetics with a half‐life of 93 min. The disposition followed a three‐phasic exponential time‐course with half‐lives of 1.1, 17 and 98 min., respectively, which was interpreted as three‐compartment kinetics. The drug accumulated 430 times in the myocardium at steady‐state with 8, 30 and 61% of the drug amount referable to a central, superficial and two deeper myocardial drug pools. GBR 12909 produced concentration dependent (range 0.01 to 12400 nM) biphasic negative inotropic and chronotropic effects. The inhibitory Em‐values with regard to contraction velocity were 42 and 105% with corresponding EC50‐values of 29 and 688 nM and the related Hill‐exponents were 0.6 and 1.1, respectively. Frequency and contraction amplitude related inhibitory Em‐values were of similar size. Apparent dynamic steady states developed within about 17 min. Very marked monophasic negative dromotropic effects were observed with computer‐derived inhibitory Em‐values related to the electrocardiographic PQ‐ and QRS‐intervals exceeding 100%. The frequency‐corrected QTc‐interval showed an initial increase of 10% but decreased to about 20% below control level at the highest two drug concentrations. Coronary flow‐rate increased about 30% and then gradually decreased to near the control value. Oxygen consumption only decreased at the three highest concentrations. Our findings seem compatible with the view that GBR 12909 may possibly act in the myocardium as a membrane‐stabilizer which causes inhibition of Na+‐ and Ca++‐influx over sarcolemma. Intracellular inhibition of Ca++‐liberation from organelles and other calcium depots also seems possible.
Depressant Effects of L‐Tyrosine on Isolated Perfused Rat and Rabbit Hearts
Authors: Ekholm Sari , Ruskoaho Heikki , Karppanen Heikki
Published: March 2009

Tyrosine exerts potent cardiovascular effects: smaller doses induce tachycardia and hypertension while higher doses induce bradycardia and hypotension. However, the direct cardiac effects of this amino acid have not been characterised. In the present study increasing doses of L‐tyrosine were administered to the perfusate of isolated rat (0.01–10.0 mg) and rabbit (0.5–40.0 mg) hearts. Heart rate and isometric force of contraction or amplitude of contractions, and either perfusion pressure or flow of perfusate were recorded. In rat hearts L‐tyrosine decreased heart rate and isometric force of contraction. In rabbit hearts L‐tyrosine also decreased heart rate and amplitude of contractions. The effects on coronary vasculature were variable. In rat hearts, high doses of L‐tyrosine induced bi‐phasic changes with initial coronary dilatation, followed by vasoconstriction. In rabbit hearts the predominant effect of L‐tyrosine was coronary artery constriction. These results show that the inhibitory cardiovascular effects of L‐tyrosine in vivo may be at least in part, explained by direct cardiac effects of this amino acid.
Distribution of 1‐(3H)methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (3H‐MPTP) in the Frog: Uptake in Neuromelanin
Authors: Sokolowski Annika Lydén , Larsson Bengt S. , Lindquist Nils Gunnar
Published: March 2009

The nigrostriatal toxin 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP) causes selective destruction of pigmented monoaminergic neurons of the brain, mainly in the substantia nigra. Primates and amphibians, whose nerve cells contain melanin, have shown a higher sensitivity for the toxic effects of MPTP than species which are lacking neuromelanin, e.g. rodents. In the present study the distribution after intraperitoneal injection of 3H‐MPTP in frogs (Rana temporaria) was studied by whole‐body autoradiography. Histochemical staining methods for melanin were used in order to identify the pigment in various tissues. Melanin‐containing nerve cells were present bilaterally in the ventral motor parts of the frog brain. Melanin was also found in the meninges, around the cerebral ventricles and the aqueducts, and in the eyes, skin and liver. The results from the autoradiographic study of 3H‐MPTP revealed a high accumulation and retention in all melanin‐containing structures up to 15 days after administration (the longest survival time). The pigmented tissues showed the highest concentration of radioactivity in the body at all survival times. The MPTP‐induced destruction of pigmented nerve cells may be related to the binding and storage of MPTP and/or its metabolites in neuromelanin, causing toxic cytoplasmic concentrations through the continuous release of substance from the melanin depot.
Adrenoceptor‐Activation of Oxygen Consumption in Rat Parotid Acini
Authors: Glenert Ulla , Nauntofte Birgitte
Published: March 2009

The purpose of this study was to examine the effects of various adrenergic agonists and antagonists upon rat parotid oxygen consumption. The experiments were performed using collagenase‐isolated acini, and the O2 consumption was determined using a Gilson Oxygraph 5/6 H with a Clark electrode. Stimulation with the α‐ and β‐adrenergic agonist adrenaline (10 μM) lead to a 65% increase in parotid O2 consumption in about 10 sec. Addition of adrenaline after preincubation with the β‐adrenergic antagonist propranolol or the α‐adrenergic antagonist prazosin showed that about 2/3 of the adrenaline‐induced O2 consumption originated in α‐adrenergic activity, whereas the remaining 1/3 stemmed from β‐adrenergic activity. Correspondingly, it was found that stimulation by the β‐adrenergic agonist isoprenaline (10 μM) increased the O2 consumption with approximately 22%. Stimulation with the α‐adrenergic agonist phenylephrine (10 μM) did however, only increase O2 consumption with 21%. This finding is probably not related to the existence of α‐2‐adrenoceptors stimulated by adrenaline and not by phenylephrine, since: (1) the adrenaline‐induced response was unaffected by preincubation by pertussis toxin, (an activator of the Gi protein of the adenylate cyclase complex), and (2) the stimulating effect of clonidine (an α‐2‐adrenoceptor agonist) was inhibited by preincubation with prazosin, and (3) radioligand binding studies using [3H]‐yohimbine was unsuccessful in demonstrating parotid α‐2‐adrenoceptors. Accordingly, a conclusion that accounts for the findings in this paper is that only β‐ and α1‐adrenoceptors are functioning in the parotid acini and that phenylephrine acts as a partiel α1‐agonist.
In Vitro Effects of Methylsulfonyl Polychlorinated Biphenyls and 7,8‐Benzoflavone on Aryl Hydrocarbon Hydroxylase Activity in Human Lymphoblastoid Cells
Authors: Kiyohara Chikako , Mohri Noriko , Hirohata Tomio , Haraguchi Koichi , Masuda Yoshito
Published: March 2009

The effects of 11 isomers of methylsulfonyl polychlorinated biphenyls (MSF‐PCBs) on the aryl hydrocarbon hydroxylase (AHH) activity were examined at a fixed dose of 1.5 μg/ml by using cultured lymphoblastoid cells. One of the isomers 3‐MSF‐3′,4,4′,5‐tetraCB, as well as 4‐MSF‐3,3′,4′,5‐tetraCB and 4‐MSF‐3,3′,4′,5,5′‐pentaCB, effectively reduced the AHH activity when added to the culture medium, especially that previously treated with 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin (TCDD) to induce the AHH activity. However, the inhibitory potencies exerted by the above three MSF‐PCB compounds were smaller than that by 7,8‐benzoflavone (BNF). When added to the culture medium simultaneously with TCDD or 3‐methylcholanthrene (MC), 3‐MSF‐3′,4,4′,5‐tetraCB blocked the enhancement of the AHH activity by TCDD but did not that by MC. This is in contrast to BNF which blocked the increases due to both TCDD and MC. On the other hand, 3‐MSF‐3′,4,4′,5‐tetraCB added directly to the reaction mixture for the TCDD‐induced AHH activity showed little influence, while BNF decreased the same activity. These results imply that the effect of 3‐MSF‐3′,4,4′,5‐tetraCB on the AHH activity is different from that of BNF.
Species Differences in Kidney Necrosis and DNA Damage, Distribution and Glutathione‐Dependent Metabolism of 1,2‐Dibromo‐3‐chloropropane (DBCP)
Authors: Søderlund Erik J. , Låg Marit , Holme Jørn A. , Brunborg Gunnar , Omichinski James G. , Dahl Jon E. , Nelson Sidney D. , Dybing Erik
Published: March 2009

Species differences and mechanisms of 1,2‐dibromo‐3‐chloropropane (DBCP) nephrotoxicity were investigated by studying DBCP renal necrosis and DNA damage, distribution and glutathione‐dependent metabolism in rats, mice, hamsters and guinea pigs. Extensive renal tubular necrosis was observed in rats 48 hr after a single intraperitoneal administration (21–170 μmol/kg) of DBCP. Significantly less necrosis was found in mice and guinea pigs, whereas no renal damage was evident (<680 μmol/kg) in hamsters. The activation of DBCP to DNA damaging intermediatesin vivo, as measured by alkaline elution of DNA isolated from kidney nuclei 60 min. after intraperitoneal injection of DBCP, was compared in all four species. Distinct DNA damage was detected in rats, mice and hamsters as early as 10 min. after administration of DBCP and within 30 min. in guinea pigs. Rats and guinea pigs showed similar sensitivity towards DBCP‐induced DNA damage (extensive DNA damage >21 μmol/kg DBCP), whereas in mice and hamsters a 10–50 times higher DBCP dose was needed to cause a similar degree of DNA damage. Renal DBCP concentrations at various time‐points (20 min., 1, 3 and 8 hr) after intraperitoneal administration (85 μmol/kg) revealed that the initial (20 min.) DBCP concentration was substantially higher in rats and guinea pigs compared to the other two species. Furthermore, kidney elimination of DBCP occurred at a significantly lower rate in rats than in mice, hamsters and guinea pigs. Cytosols from all four species debrominated DBCP at appreciable rates in the presence of glutathione (GSH), with kidney preparations from rats and guinea pigs being approximately two to three times more active than those from mice and hamsters. The present findings strengthen the hypothesis that DNA damage may be an initial event in DBCP organ toxicity. The extent and persistence of the DNA damage must, however, exceed a critical value to cause cell death. The high initial renal concentration of DBCP, its relatively long half‐life in the kidney and the ability of the kidney to activate DBCP in the presence of GSH all contribute to the high susceptibility of the rat kidney to DBCP‐induced nephrotoxicity.
Effects of Intravenous ATP on Tracheal Ciliary Activity, Airway Resistance and Haemodynamics in Rats
Authors: Saano V. , Muranen A. , Nuutinen J. , Karttunen P. , Silvasti M.
Published: March 2009

The effect of the intravenous administration of ATP on the airway ciliary beating frequency (CBF) of anaesthetized rat was studied by measuring CBF photoelectrically from the inner surface of incised trachea. ATP (1 or 10 mg/kg) caused no changes in the CBF, but the decrease in CBF, which was seen after 70 min. in control rats, was abolished by ATP (10 mg/kg). ATP acutely decreased blood pressure; at 10 mg/kg, the decrease was 70 mmHg in systolic, and 60 mmHg in diastolic blood pressure. ATP also tended to increase rectal temperature and airway resistance, but these effects were not significant. ECG remained normal. Intravenous administration of ATP helps to maintain the function of tracheal cilia in anaesthetized rats at doses that, although lower blood pressure, do not cause fatal untoward effects.
Effects of Some Autacoids on Breathing and Perfusion Flow in the Isolated Perfused Rat Lung
Authors: Ryrfeldt Åke , Olafsdottir Kristin , Berggren Margarets , Moldéus Peter
Published: March 2009

The effects of three autacoids ((5‐hydroxytryptamine (5‐HT), bradykinin and acetylcholine (Ach)) on breathing and pulmonary circulation were studied in the isolated perfused and ventilated rat lung after intravascular injection or intrabronchial instillation. 5‐HT, bradykinin and Ach all caused a dose related reduction in breathing, after injection into the pulmonary artery, with Ach being the most potent. With regard to effects on the pulmonary circulation, a dose‐related reduction in perfusate flow was noted with bradykinin and 5‐HT with bradykinin being about 10 times more potent than 5‐HT. Ach did not reduce or increase perfusate flow. After intrabronchial instillation only 5‐HT caused reduced perfusate flow. Effects on breathing were difficult to evaluate with this route of administration. The isolated perfused and ventilated lung seems to be a usable model to simultaneously study effects on respiration and pulmonary circulation.
Effects of κ‐ and μ‐Selective Opiate Agonists on Colonic Temperature in Normoglycaemic and Streptozotocin‐Treated Hyperglycaemic Mice*
Authors: Bansinath M , Ramabadran K. , Turndorf H. , Puig M. M.
Published: March 2009

The thermic responses of highly selective κ‐(U‐69593 and U‐50488H) and μ(sufentanil and fentanyl) agonists were assessed in normoglycaemic and hyperglycaemic mice. Hyperglycaemia was induced by streptozotocin injection. The opiates were injected subcutaneously and colonic temperatures monitored for 90 min. after injection. In normoglycaemic animals the k‐agonists induced a significant hypothermic response and hyperglycaemia did not modify this effect. In normoglycaemic mice, low doses of μ‐selective agonists predominantly produced hypothermia, while in high doses resulted in hyperthermia. In chronic hyperglycaemic mice, hyperthermia was the predominant effect of μ‐opiates. The present results characterize the time couse and dose response of some of the currently available highly selective k‐ and μ‐opiate agonists for the first time in mice and suggest that hyperglycaemia differentially affects the opiate receptor subtypes that mediate thermoregulatory events.
Comparison of the Sensitivity of Human and Rat Hepatocytes to the Genotoxic Effects of Metronidazole
Authors: Martelli Antonietta , Allavena Alessandra , Robbiano Luigi , Mattioli Franceses , Brambilla Giovanni
Published: March 2009

Metronidazole (MNZ), an antiprotozoan and antibacterial agent, has been shown to yield DNA‐damaging reactive species after nitroreductive biotransformation. The genotoxic effect of MNZ was studied in primary cultures of both rat and human hepatocytes. In millimolar concentrations MNZ produced DNA fragmentation, as measured by the alkaline elution technique, and unscheduled DNA synthesis, as evaluated by quantitative autoradiography, in rat hepatocytes. The amount of DNA damage was directly related to the dose and the length of exposure, was increased by hypoxia and GSH depletion, and was markedly reduced by inhibition of cytochrome P‐450 activity. In the same experimental conditions human hepatocytes resulted constantly more resistant than rat hepatocytes to the genotoxic activity of MNZ. These findings suggest that the rat hepatocyte model might be an inappropriate predictor of nitroimidazoles genotoxicity.
Codeine in Analgesic Doses Does not Depress Respiration in Patients with Severe Chronic Obstructive Lung Disease
Authors: Munck Lars Kristian , Christensen Christian Broen , Pedersen Linda , Larsen Ulla , Branebjerg Poul Erik , Kampmann Jens Peter
Published: March 2009

Nineteen normocapnic patients with chronic obstructive lung disease participated in an open single dose safety study (part one) followed by a randomized double‐blind cross‐over study comparing two seven‐days treatment periods of 1 g of paracetamol t.i.d. with 60 mg of codeine plus 1 g of paracetamol t.i.d., respectively (part two). In part one, continuous monitoring after a single dose of 2 g of paracetamol and 120 mg of codeine revealed no deterioration in the respiration and gas tensions. In part two, respiratory parameters and arterial gas tensions were recorded one hour after the last morning dose. PaCO2 increased insignificantly (0.05<P<0.10) by a median of 0.38 kPa during treatment with codeine and paracetamol compared to treatment with paracetamol alone. PaO2 decreased by 0.12 kPa (P>0.10). There was no correlation between changes in PaCO2 and changes in PaO2. FVC, FEV1 and dyspnoe at rest were unchanged. Gastrointestinal side effects were reported significantly (P < 0.02) more often during treatment with codeine plus paracetamol. There was no correlation between the plasma concentration of codeine or morphine and changes in respiratory parameters or adverse effects. The limitation for the short time clinical use of codeine as an analgesic to normocapnic patients with severe chronic obstructive lung disease in stable phase seem to be gastrointestinal side effects.
Mechanisms of Absorption of Inorganic Mercury from Rat Small Intestine. III. Comparative Absorption Studies of Inorganic Mercuric Compounds in Vitro
Authors: Endo Tetsuya , Nakaya Shozo , Kimura Ryohei
Published: March 2009

The transport of various inorganic mercuric compounds (HgX2s) was compared in everted intestinal sacs and intestinal brush border membrane vesicles (BBMV) of the rat. The preparations were incubated in a medium containing 10‐4 M HgX2 at pH 5.5, 6.4 or 7.4, respectively. The order of transport through the intestinal wall at each pH (HgOAc)2 > HgCl2 > Hg(SCN)2 > HgBr2 > Hg(CN)2) was the reverse order of their stability constants, and an increase in pH tended to increase the transport of HgX2. In the experiment with BBMV, similar results were obtained except for the transport of Hg(CN)2. These results suggest that the extent of transport of a certain HgX2 depends on its stability constant, and that the increase in pH promotes the transport possibly as a result of the conversion of HgX2 to Hg(OH)X and Hg(OH)2.
The Effects of Age and Dietary Protein Restriction on the Pharmacokinetics of Theophylline in the Rat
Authors: Jung Donald , Nanavaty Maulik
Published: March 2009

The influence of dietary protein levels on theophylline kinetics was examined in male Fischer 344 virgin rats of 2, 14 and 20 months of age fed for four weeks on a 23% (control) or 5% (low) protein dietad libitum.Protein deficiency led to a significant decrease in body weight gain for the 2 month old rats (10.9% versus 26.5%). In addition, decreases in total body weight of 7.5% and 15.3% were seen for the 14 and 20 month old rats, respectively, on a low protein diet. Total proteins and albumin levels in plasma were not significantly affected by age or dietary protein levels. After intravenous administration of 10 mg/kg aminophylline, the average mean residence time (MRT) was significantly longer in 20 month old rats as compared to the younger rats, while 14 month old rats had a greater elimination rate constant than the 2 and 20 month old rats. There were significant reductions in the mean steady‐state apparent volume of distribution (Vss) in the 2 and 14 month old rats on a low protein diet of 31% and 18%, respectively, while there was no difference between the diets in 20 month old rats. In addition, the Vss decreased from 0.71 L/kg to 0.57 L/kg in the 2 and 20 month old rats, respectively, on a normal protein diet. Dietary protein deficiency led to a significant reduction of total body clearance from approximately 73 to 45 ml/hr/kg in the 2 and 14 month old rats. Interestingly, although there appeared to be a diet‐related impairment of theophylline metabolism in the younger rats, theophylline clearance was approximately 45 ml/hr/kg in the 20 month old rats, irrespective of dietary protein level.
Diazepam Attenuates Morphine Antinociception Test‐Dependently in Mice
Authors: Rosland Jan Henrik , Hunskaar Steinar , Hole Kjell
Published: March 2009

The influence of diazepam on the antinociceptive effect of morphine was studied using four different nociceptive tests in mice. In the tail flick test, diazepam induced a dose‐dependent reduction of the morphine effect, with an almost total reversed morphine effect following diazepam 2 mg/kg. The effect could not be explained by altered tail skin temperature or pharmacokinetic changes. Diazepam 1 mg/kg and higher induced sedation and significantly impaired the performance in a rotarod test, a dose of 0.5 mg/kg diazepam was therefore used in the other nociceptive tests. This dose of diazepam significantly attenuated the antinociceptive effect of morphine in the constant temperature hot plate test and the tail flick test. In the increasing temperature hot plate test and in the formalin test, no effect of diazepam on the nociceptive effect of morphine was observed. The results indicate that diazepam antagonizes the effect of morphine dependent upon the test employed. No antagonism could be observed in tests with a long‐lasting stimulus, and a response integration probably at a rather high level in the CNS. In the two tests showing antagonism, the stimulus is more short‐lasting, and at least for the tail flick test, the integration takes place at a lower level in the CNS.
Effects of Age on Susceptibility of Chickens to Delayed Neurotoxicity Due to Triphenyl Phosphite
Authors: Katoh Kiyoshi , Konno Nobuhiro , Yamauchi Toru , Fukushima Masaaki
Published: March 2009

Triphenyl phosphite (TPP), which is widely used in the chemical industry, is known to produce delayed neurotoxicity in some experimental animals. The effects of aging on the susceptibility to TPP, its disposition and pharmacokinetics, and itsin vitrodegradation by liver homogenate were studied in chickens. Chickens aged 60 days or less at administration were not affected, but 10 of 15 chickens aged 90 to 180 days developed ataxia 10 to 12 days after the intravenous injection of TPP (50 mg/kg). TPP clearance from the blood and most of the tissues examined was faster in 45‐day‐old chickens than in 135‐day‐old chickens. The biological half‐life of TPP in the blood was 23.2 min. in the younger group and 30.5 min. in the older group. In thein vitroexperiment, the initial TPP concentration of 1.6 × 10‐5M fell to less than half this level within 60 min. during incubation with liver homogenates from 45‐day‐old chickens, whereas with homogenates from 135‐day‐old chickens the level remained high. These results suggested that the age‐specific susceptibility to TPP was related to the differences of the tissue load, which derived in part from differing levels of metabolic activity in the liver.
Tolerance During Inhalation of Organic Solvents
Authors: Kjellstrand P. , Månsson L. , Holmquist B. , Jonsson I.
Published: March 2009

Inhalation of several different halogenated solvents stimulated motor activity in mice. During prolonged exposure acute tolerance developed. The development of tolerance depended both on the schedule of exposure, and on the solvent. Exposure to trichloroethylene induced both stimulation and tolerance while the same degree of stimulation induced by 1,1,1‐trichloroethane caused no tolerance. Thus the mechanisms which induce stimulation do not always initiate tolerance. Slow steady increases in the concentration of trichloroethylene could be maintained for several hours without any stimulation of motor activity. At the end of such exposures concentrations were reached which, if applied directly, would have induced considerable stimulation. Thus tolerance may develop without motor stimulation. Inhalation of ethanol also stimulated motor activity initially. During constant exposure the stimulation was followed by a considerable reduction in motor activity. This resulted in a hypoactive period, which in turn was followed by a second increase in motor activity, indicating the existence of not only two but several counteracting mechanisms. Development of metabolites with sedative effects counteracting the stimulating effect of the pure solvents seems to be one explanation for the results.
Haem‐Dependent Activation of Guanylate Cyclase and Cyclic GMP Formation by Endogenous Nitric Oxide: A Unique Transduction Mechanism for Transcellular Signaling
Authors: Ignarro Louis J.
Published: March 2009

The interaction between nitric oxide (NO) synthesized in one cell and the haem group of cytosolic guanylate cyclase located in target cells to form NO‐haem‐guanylate cyclase represents a unique signal transduction mechanism that links extracellular stimuli to the synthesis of cyclic GMP in nearby target cells. Autacoids, neutrotransmitters, and macrophage‐ and neutrophil‐activating factors interact with selective extracellular receptors to trigger formation of NO from L‐arginine. NO may be viewed as a second messenger. The NO diffuses into adjacent target cells and causes haem‐dependent activation of guanylate cyclase, thereby stimulating cyclic GMP accumulation. Guanylate cyclase‐bound haem serves as a transducer in transferring the signal from NO to guanylate cyclase. Cyclic GMP acts as a third messenger in causing vascular smooth muscle relaxation, inhibition of platelet aggregation and adhesion, and modulation of macrophage, neutrophil, and other phagocytic cell functions. The unique physical and chemical properties of NO allow it to function as an intercellular modulator within a localized environment. This intercellular or transcellular signaling mechanism involving a common signal transduction mechanism permits the rapid initiation of localized complementary cellular functions leading to increased local blood flow, inhibition of local thrombosis, and modulation of phagocytosis and cytotoxicity.
Sparteine Metabolism Capacity in Human Liver: Structural Variants of Human P450IID6 as Assessed by Immunochemistry
Authors: Tyndale R. F. , Gonzalez F. J. , Hardwick J. P. , Kalow W. , Inaba T.
Published: March 2009

An antibody raised against rat P450dbl was used to examine the heterogeneity of the human enzyme involved in the sparteine/debrisoquine polymorphism. The extent to which the antibody was able to inhibit sparteine metabolism varied in different human livers (10–80%, n = 9) and reflected the amount of sparteine metabolism carried out by the polymorphic P450IID6 in individual liver specimens. The individual sample variation in inhibition by the antibody correlated with the inhibition caused by quinidine, a prototype competitive inhibitor of the P450IID6 enzyme active site. Western immunoblots of the liver microsomes confirmed that the variation in the inhibition of sparteine metabolism by this antibody reflected the amount of P450IID6 protein. In addition, a detailed study of one of the livers (K 19) which demonstrated a lack of inhibition by the antibody was performed which confirmed the lack of P450IID6 in this liver specimen and suggested that the nascent sparteine metabolism activity was due to other forms of P450.
Dose‐Related Accumulation of Organophosphate Phosphamidon in Discrete Regions of the CNS: Correlation with its Neurotoxicity
Authors: Naqvi S. M. Z. , Hasan Mahdi
Published: March 2009

Phosphamidon was detected by thin‐layer chromatography (TLC) from various CNS regions of the rats intoxicated with three doses (1.0, 1.5 and 2.0 mg/kg body‐weight) intraperitoneally daily for seven days. A distinct dose‐related increase in its concentration was observed in all investigated areas of the CNS. Regions with higher gray matter composition showed greater uptake of phosphamidon compared to those rich in white matter. This is in accordance with our previous study (Naqvi et al. 1988) revealing similar pattern in the effect of phosphamidon on the phospholipids in the brain.
Effects of Corn Oil Addition to the Diet on the Energy Metabolism of Heart, Liver and Kidney of Female Rats
Authors: Bachmann Elisabeth , Weber Elisabeth
Published: March 2009

Female rats (SIV‐50, Sprague Dawley) given a diet enriched with corn oil (10% and 25% addition to rat chow, w/w) for four weeks showed changes in the energy metabolism of heart, liver and kidneys, that is, changes in oxygen consumption and uncoupling of oxidative phosphorylation of heart, liver and kidney mitochondria, concomitant to a decrease in heart mitochondrial creatine kinase activity and an increase in heart mitochondrial creatine content. The high fat diet also affected calcium binding and Na/K‐, Mg‐ and Ca‐ATPases of a cardiac myocyte membrane fraction. Lipid feeding also led to increase (biphasic and transient) of phospholipids, triglycerides and free fatty acids in the three organs studied, but in no case to hyperthrophy.
Autoradiography of 3H‐α‐Fluoromethyl Histidine in Mice: Correlation with the Kidney Histidine Decarboxylase Activity
Authors: Hammar Lena , Henningsson Stig , Henningsson Anne‐Charlotte , Appelgren Lars‐Erik , Tjälve Hans , Kollonitsch J.
Published: March 2009

Tritium‐α‐fluoromethyl histidine (3H‐α‐FMH), designed as a kcat‐inhibitor of mammalian histidine decarboxylase (EC 4.1.1.22), was administered intravenously in male and pregnant female mice of the NMRI strain and the distribution of tritium in the body recorded by whole‐body and microautoradiography. The results showed penetration of radioactivity into most tissues within 5 min. after the injection. After 4 hrs the highest levels of radioactivity were present in the intestinal content and in the kidneys. In the pregnant animal there was also a high labelling of the foetal tissues. When whole‐body sections were washed in TCA prior to the autoradiographic exposure to retain only protein‐bound radioactivity, a distinct labelling pattern was seen in the kidneys of the pregnant female mice but not in those of the male mice. Microautoradiography of the kidneys showed that the cells involved were located within the proximal convoluted tubuli. In several mouse strains, including the NMRI, the activity of kidney histidine decarboxylase is low in the males but high in females during a transient period of pregnancy. Incorporation of tritium into kidney protein after treatment with 3H‐α‐FMH, was correlated to a loss in histidine decarboxylase activity. The isotopic labelling was confined mainly to a component which cofractionated with histidine decarboxylase in polyacrylamidegel electrophoresis (PAGE) under non‐denaturing conditions. Our data indicate that the cells described above represent the location of kidney histidine decarboxylase.
Influence of Interleukin‐1β on the Secretion of Oxytoxin and Vasopressin from the Isolated Rat Neurohypophysis
Authors: Christensen Jens D. , Hansen Erik W. , Fjalland Bjarne
Published: March 2009

The effect of the cytokine interleukin‐1β on the secretion of oxytocin and vasopressin from electrically stimulated rat neurohypophysis was examined in vitro. The release of oxytocin and vasopressin was concentration‐dependently increased by interleukin‐1β in the concentration range from 4.4 pM to 440 pM. The effect of interleukin‐1β on oxytocin secretion was less intense as compared to vasopressin. After 440 pM interleukin‐1β the electrically evoked release of oxytocin was increased about 22% and had not reached its maximum. The vasopressin response was maximal after 44 pM interleukin‐1β, the response being increased 43% compared to control. No trace of interleukin‐1β was found in the posterior pituitary (<350 pmol/lobe, radioimmunoassay). The results indicate that interleukin‐1β might be involved the the regulation of oxytocin and vasopressin at the pituitary level.
Animal Models of Parkinsonism
Authors: Kaakkola Seppo , Teräväinen Heikki
Published: March 2009

The discovery of profound dopamine depletion of basal ganglia in patients with Parkinson's disease and the development of antiparkinsonian drug therapy were largely based on animal models. The behavioural changes caused by cholinergic drugs, reserpine and related agents, and unselective neuronal lesions were the first widely used animal models for Parkinson's disease. The crucial breakthrough was the observation of the circling behaviour in rodents after unilateral intranigral injection of 6‐hydroxydopamine. This Ungerstedt model still is one of the basic animal models of Parkinson's disease. It is suitable for the screening of new potential antiparkinsonian agents with the classic spectrum. The parkinsonism induced by the neurotoxin 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP) in the mouse and the monkey is the latest and the best animal model for Parkinson's disease. Especially when given to the monkey, MPTP causes biochemical, behavioural and neuropathological changes which largely mimick those of Parkinson's disease in man. The MPTP‐induced parkinsonism in the monkey can be used for the study of the neurobiology and new forms of drugs therapy of Parkinson's disease. However, because the MPTP monkey model is expensive and laborious, it is not particularly convenient for the screening of new drugs. Recently, a new approach in the treatment of Parkinson's disease is to develop drugs which might prevent or retard the disease progression. The prevention of behavioural changes of aged rodents is used as an animal model and promising results with selegiline have been obtained.
The Effect of Amiloride on the Cardiac Chronotropic Responses to Isoproterenol in Myocardial Aggregate Cells in Culture
Authors: Rabkin Simon W.
Published: March 2009

The purpose of this study was to test the hypothesis that amiloride alters the response of cardiac myocytes to isoproterenol. Myocardial cell aggregates were prepared from 7 day‐old chick embryos maintained in culture for 72 hrs before study. Isoproterenol, 10‐8 M to 10‐5 M, significantly (P<0.05) increased contractile frequency of myocardial aggregates. The effects of isoproterenol were maximum within 5 min. of exposure and declined thereafter. In the absence of isoproterenol, amiloride, at 10‐6 M and 10‐7 M produced a transient decrease in contractile frequency while amiloride at 10‐5 M produced a significant (P<0.05) decrease in contractile frequency. Amiloride significantly (P<0.05) increased the effect of isoproterenol on cardiac contractile frequency. There was a greater and more sustained response to isoproterenol in the presence of amiloride. Furthermore, the magnitude of these effects were greater with higher concentrations of amiloride. These data indicate that amiloride accentuates the cardiac chronotropic response to isoproterenol and suggest that, because amiloride inhibits sodium entry in these cells, change in intracellular sodium may be one of the mechanisms mediating the chronotropic action of isoproterenol on the heart.
Antagonism of Acetaminophen‐Induced Hepatocellular Destruction by Trifluoperazine in Mice
Authors: Yamamoto Hiro‐aki
Published: March 2009

The effect of trifluoperazine, a specific calmodulin inhibitor, on hepatocellular destruction induced by acetaminophen was investigated in mice. Trifluoperazine 30 mg/kg administered intraperitoneally 30 min. or 0 min. before acetaminophen blocked hepatocellular destruction induced by the hepatotoxin, as evidenced by the determination of plasma GPT activity. Trifluoperazine also completely inhibited an increase of calcium contents in liver induced by acetaminophen administration. Furthermore, the increase of hepatic phosphorylase a activity induced by acetaminophen administration was completely abolished by pretreatment with trifluoperazine. However, hepatic glutathione depletion induced by acetaminophen was not prevented by pretreatment with trifluoperazine. Trifluoperazine administration caused a marked decrease in the body temperature of acetaminophen‐treated animals. However, when the trifluoperazine‐treated acetaminophen‐poisoned animals were kept normothermic, the preventive effects were abolished. These findings suggest that this protective effect may be mediated by the trifluoperazine blockade of the deleterious effects of calcium accumulation in liver or the trifluoperazine decreasing effects on body temperature.