Search results for "RATS"

Structure-activity relationship of furosemide-derived compounds as antagonists of cerebellum-specific GABA(A) receptors.

1998

The Na+-K+-2Cl- cotransporter blocker furosemide inhibits gamma-aminobutyric acid (GABA)-gated chloride currents and reverses GABA-mediated inhibition of [35S]-t-butylbicyclophosphorothionate ([35S]TBPS) binding of the cerebellar alpha6 subunit-containing GABA(A) receptors much more potently than the cerebrocortical non-alpha6 subunit-containing receptors. Of the 44 compounds studied, all precursors or derivatives of diuretics, one compound [hydrazinosulfonyl-furosemide (PF 1885)] reversed 5-microM GABA-induced inhibition of [35S]TBPS binding to cerebellar and cerebrocortical receptors. Three other compounds, all of which are structurally closely related to furosemide, were selective antago…

Effects of (+)-tubocurarine on [3H]acetylcholine release from the rat phrenic nerve at different stimulation frequencies and train lengths

1987

The effect of (+)-tubocurarine (TC) on the release of [3H]acetylcholine from the rat phrenic nerve-hemidiaphragm preincubated with [3H]choline was investigated at different stimulation frequencies and train lengths. At 0.5 Hz (100 pulses) TC failed to modulate the evoked acetylcholine release. A slight (30%) inhibition was observed at 1 Hz (100 pulses). Release of acetylcholine evoked at 5, 25 and 50 Hz (100 pulses) or 100 Hz (200 pulses) was markedly reduced by TC. The degree of inhibition (60%) was similar between 5 Hz and 100 Hz. A concentration of 1 mumol/l TC was a maximal effective concentration at 5 Hz whilst at all higher stimulation frequencies a 10-fold higher concentration was ne…

Action of tertiary phenylalkylamines on cardiac transient outward current from outside the cell membrane.

1996

The effects of the phenylalkylamines verapamil (V), gallopamil (G), and devapamil (D) and their corresponding quaternary derivatives on the transient outward current (Ito) were examined in rat ventricular cardiomyocytes using the whole-cell patch-clamp technique. The question was addressed, whether phenylalkylamines act on Ito from the inside or the outside or from both sides of the cell membrane. To this end, the myocytes were either superfused extracellularly or perfused intracellularly with drug-containing solutions. In addition, the effects of verapamil were investigated at different pH-values. V, G, and D (30 microM each), applied extracellularly, reduced the steady state current of It…

A two-circuit apparatus for the perfusion of the isolated rat brain.

1973

A perfusion apparatus for the isolated rat brain is described which has two recirculating systems running synchronously. Instantaneous transfer from one circulating system to the other is possible by use of a 2-way stopcock, enabling different media to be perfused through the brain without interrupting the perfusion. The feasibility of the system is demonstrated experimentally.

Nitric oxide synthase: expression and expressional control of the three isoforms.

1995

Three isozymes of nitric oxide synthase (NOS) have been identified. Their cDNA- and protein structures as well as their genomic DNA structures have been described. NOS I (ncNOS, originally discovered in neurons) and NOS III (ecNOS, originally discovered in endothelial cells) are low output, Ca(2+)-activated enzymes whose physiological function is signal transduction. NOS II (iNOS, originally discovered in cytokine-induced macrophages) is a high output enzyme which produces toxic amounts of NO that represent an important component of the antimicrobial, antiparasitic and antineoplastic activity of these cells. Depending on the species, NOS II activity is largely (human) or completely (mouse a…

Isolation of endothelin A receptor from bovine lungs.

1995

We isolated endothelin receptor A (ET A ) from bovine lungs in a single-step purification procedure using antibodies raised against synthetic peptides that correspond to extra- and intracellular domains of the rat bradykinin receptor. Two receptor species of 55 and 35 kDa were isolated and subjected to N-terminal microsequencing. The difference between the observed and expected molecular weight species suggests that bovine ET A receptor is glycosylated.

The effect of β-mercaptoethanol on lactate dehydrogenase from rat brain

1963

Abstract Catalytic studies on lactate dehydrogenase from rat brain in the presence of β-mercaptoethanol have been performed. It has been found that pyruvate reduction and lactate dehydrogenation were differently affected by the addition of the sulfhydryl compound to the reaction mixture. The effect of β-mercaptoethanol on the catalyzed reaction has been shown to be dependent on the hydrogen ion concentration. When lactate dehydrogenation is measured, β-mercaptoethanol causes a net enhancement of the reaction rate at the more acidic pH values.

Evaluation of alprazolam-induced behavioural effects: differences with chlordiazepoxide after interaction with desipramine and rolipram, a cAMP phosp…

1989

Head-twitch and forepaw-shake responses after single and repeated treatment with rolipram: interaction with noradrenergic and dopaminergic agonists a…

1988

Nonlinear intestinal absorption kinetics of cefuroxime axetil in rats.

1997

Cefuroxime is commercially available for parenteral administration as a sodium salt and for oral administration as cefuroxime axetil, the 1-(acetoxy)ethyl ester of the drug. Cefuroxime axetil is a prodrug of cefuroxime and has little, if any, antibacterial activity until hydrolyzed in vivo to cefuroxime. In this study, the absorption of cefuroxime axetil in the small intestines of anesthetized rats was investigated in situ, by perfusion at four concentrations (11.8, 5, 118 and 200 microM). Oral absorption of cefuroxime axetil can apparently be described as a specialized transport mechanism which obeys Michaelis-Menten kinetics. Parameters characterizing absorption of prodrug in free solutio…