Search results for "Inbred strain"

STIMULATION OF ?1-ADRENOCEPTORS ENHANCES ELECTRICALLY EVOKED [3H]-ACETYLCHOLINE RELEASE FROM RAT PHRENIC NERVE

1990

1. The effects of isoprenaline, noradrenaline and fenoterol on the electrically evoked release of [3H]-acetylcholine from the rat phrenic nerve were investigated. 2. Isoprenaline (0.1 mumol/L) and noradrenaline (1 mumol/L) enhanced evoked [3H]-acetylcholine release by about 90%, an effect which was abolished by CGP 20712A (0.1 mumol/L), a specific antagonist at beta 1-adrenoceptors. Noradrenaline still enhanced [3H]-acetylcholine release in the presence of phentolamine (1 mumol/L). 3. The enhancing effect of both isoprenaline and noradrenaline decreased at prolonged exposure times (24-32 min). A pre-exposure of the tissue to a low concentration (0.01 mumol/L) of isoprenaline prevented the e…

Irreversible binding of acrylonitrile to nucleic acids

1983

1. [2,3-14C]Acrylonitrile was incubated with rat-liver microsomes, NADPH and either DNA, RNA or bovine serum albumin. Irreversible binding occurred to the macromolecular targets. Binding was lower when incubations were performed without microsomes. 2. Most of the 14C bound to DNA, RNA or polynucleotides (poly-A, poly-C, poly-G, poly-U) after incubation of [2,3-14C]acrylonitrile with rat-liver microsomes and 'conventional' re-isolation of the nucleic acids was removed from the macromolecular target when subsequently chromatographed on hydroxyapatite. 3. Radioactivity attached to DNA after prolonged non-enzymic incubations with [2,3-14C]acrylonitrile was also removed from the DNA by chromatog…

Increased Level of Intracellular MHC Class II Molecules in Murine Langerhans Cells Following In Vivo and In Vitro Administration of Contact Allergens

1992

Treatment of murine Langerhans cells (LC) with contact allergens results in increased internalization of cell membrane constituents and therefore in depressed cell-surface expression of major histocompatibility complex (MHC) class II molecules during the first hours after haptenization. In this presentation we show that this downregulation of cell-surface-expressed Ia-antigens is accompanied by an augmentation of the intracellular pool of MHC class II molecules. Rat MoAb 2G9 was developed, which recognizes IA and IE molecules of the d-haplotype. This MoAb competes with the murine MoAb MK-D6 for binding sites to IAd-molecules. After blocking the cell-surface-expressed molecules with 2G9 and …

Activation of L-arginine transport by protein kinase C in rabbit, rat and mouse alveolar macrophages

1998

1 The role of protein kinase C in controlling L-arginine transport in alveolar macrophages was investigated. 2 L-[3H]Arginine uptake in rabbit alveolar macrophages declined by 80 % after 20 h in culture. 4β-Phorbol 12-myristate 13-acetate (PMA), but not 4α-phorbol 12-myristate 13-acetate (α-PMA), present during 20 h culture, enhanced L-[3H]arginine uptake more than 10-fold. Staurosporine and chelerythrine opposed this effect. 3 L-[3H]Arginine uptake was saturable and blockable by L-lysine. After PMA treatment Vmax was increased more than 5-fold and Km was reduced from 0.65 to 0.32 mM. 4 Time course experiments showed that PMA increased L-[3H]arginine uptake almost maximally within 2 h. This…

Xenobiotic metabolizing enzymes of rat liver nonparenchymal cells.

1986

Abstract The nonparenchymal cells (NPC) of the liver are primarily located along the sinusoids and therefore are the first cells to encounter blood-borne xenobiotics. To study the possible role of the NPC in the metabolism of xenobiotics, populations of NPC and parenchymal cells (PC) were prepared from rats and various xenobiotic metabolizing enzyme activities investigated. The specific activity of every enzyme studied (ethoxyresorufin deethylase, benzphetamine demethylase, glutathione transferase, UDP glucuronosyltransferase, and microsomal epoxide hydrolase) was 12 to 1000% higher in the PC than in the NPC populations and the patterns of activities between the two populations were remarka…

THE DISTRIBUTION OF UDP-GLUCURONOSYLTRANSFERASES IN RAT-LIVER PARENCHYMAL AND NONPARENCHYMAL CELLS

1992

Activities for the glucuronidation of 1-naphthol, morphine and bilirubin as well as for the sulfation of 2-naphthol have been determined in homogenates of parenchymal, Kupffer and endothelial cells isolated from livers of untreated and Aroclor 1254-pretreated rats. In addition, Western blot analyses using different polyclonal antibodies against UDP-glucuronosyltransferases (UDP-GTs) were performed with similar preparations. All enzymes under investigation were expressed at high levels in liver parenchymal cells. The constitutive expression and inducibility of UDP-GT isozyme(s) for 1-naphthol glucuronidation was also clearly demonstrated in Kupffer and endothelial cells. Furthermore, the pre…

A comparative study of drug-metabolizing enzymes present in isolated rat liver parenchymal, Kupffer and endothelial cells

1987

Long-term effects of commercial and congeneric polychlorinated biphenyls on ethane production and malondialdehyde levels, indicators of in vivo lipid…

1988

Ethane exhalation was increased in male Sprague-Dawley rats following a single intraperitoneal (IP) injection of Aroclor 1254 (500 mg/kg). In the first 2 weeks following Aroclor 1254 treatment, the increase in ethane exhalation was due to an inhibition of metabolism of endogenous ethane rather than to an increase in ethane production. In weeks 3 and 4 following Aroclor 1254 administration, metabolic clearance of ethane returned to and exceeded control levels, while ethane production increased to approximately twice the control rates (day 30). The HPLC determination of in situ hepatic malondialdehyde levels revealed a 2-fold increase in malondialdehyde content on day 30 following the Aroclor…

The Anticonvulsant FCE 26743 is a Selective and Short-acting MAO-B Inhibitor Devoid of Inducing Properties towards Cytochrome P450-dependent Testoste…

1994

Abstract The effects of the potent anticonvulsant FCE 26743 ((S)-2-(4-(3-fluorobenzyloxy)benzylamino)propionamide) on monoamine oxidase (MAO) activity were measured in-vitro and ex-vivo using rat tissue homogenates. In-vitro, FCE 26743 showed potent and selective inhibitory properties towards liver MAO-B, with IC50 values about 10−7  m for MAO-B and higher than 10−5  m for MAO-A. When determined ex-vivo in brain, the ED50 value for the inhibition of MAO-B was 1·1 mg kg−1 (p.o.) 1 h post-dosing, whereas MAO-A remained virtually unaffected after administration of 60 mg kg−1. Similar effects were seen in liver. Following oral administration of 5 mg kg−1 FCE 26743 to rats, brain MAO-B inhibitio…

Studies on the reliability of a bihyperbolic functional absorption model. II. Phenylalkylamines

1987

Evidence is given that demonstrates the reliability of the bihyperbolic equation, proposed by Pla-Delfina and Moreno, in fitting the correlation between absorption rate constants (ka) found in the small intestine and in the colon of the living anesthetized rat, and partition constants (1/R.F−1), for a series of phenylalkylamines, a group of compounds which differ largely from others which have been tested. Emphasis is laid on the nonexistence of an optimum of lipophilicity for intestinal absorption/partition correlation: This feature makes inapplicable the probabilistic approaches to the reported data.