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At least 991 records · Page 55Linked to original sources
PubMed1992

Effects of barbiturates with or without liver-tumor-promoting activity on survival and DNA synthesis of suckling and adult rat hepatocytes in serum-free primary culture.

The effects of four barbiturates with or without liver-tumor-promoting activity were examined on survival and deoxyribonucleic acid (DNA) synthesis of suckling and adult rat hepatocytes in serum-free primary culture: Of the four barbiturates, two promoters, phenobarbital and barbital, enhanced DNA synthesis of suckling rat hepatocytes at low concentrations of 0.5-2 mM or 0.5 mM, but suppressed it at high concentrations of 3 mM or 1.5-4 mM. DNA synthesis of adult rat hepatocytes was, however, only suppressed by phenobarbital within the dose range tested of 1-3 mM. On the other hand, two remaining non-promoters, barbituric acid and amobarbital, did not increase but only suppressed DNA synthesis of suckling rat hepatocytes within the dose ranges of 0.5-4 mM and 0.05-0.5 mM respectively. Phenobarbital and amobarbital were effective for supporting survival and maintaining morphological features of suckling and adult rat hepatocytes at the relatively high concentrations of 3-4 mM and 0.5-0.75 mM respectively. However, barbital and barbituric acid were ineffective for maintenance of hepatocytes. The results show that the ability to support survival of primary cultured hepatocytes is not a common property of liver-tumor-promoter barbiturates but is a common property of some barbiturates with high lipophilicity, and that the maintenance of hepatocytes by phenobarbital or amobarbital is not due to a counterbalance of stimulated proliferation and death of the cells.

Aging↗
PubMed1974

Drug uptake by brain. II. Barbiturate uptake alters the transport of amino acids in vitro(1).

1. Valine and leucine uptake into mouse brain slices was stimulated by 1 to 4 mM phenobarbital and pentobarbital. Greater concentrations of these two barbiturates inhibited the transport of these amino acids. Barbital, isobarbituric acid, and 5-nitrobarbituric acid had no effect, while amobarbital and secobarbital produced only inhibition of uptake. 2. Transport of glutamate and aspartate was unaffected by phenobarbital concentrations that inhibited uptake of lysine and alpha-aminoisobutyric acid. 3. Changes in the Na+ and K+ content of the slices were not related to stimulation of valine or leucine uptake. 4. There was no concentrative uptake of phenobarbital by brain slices. The partially saturable uptake of pentobarbital was not by active transport, because the uptake increased after heating brain, liver, or kidney slices to 95 degrees for 10 min. 5. This study shows that individual members of a pharmacologically related group may have specific effects on a composite physiological function (amino acid transport) of brain tissue.

Amino Acids↗
PubMed1983

Brain free fatty acids, edema, and mortality in gerbils subjected to transient, bilateral ischemia, and effect of barbiturate anesthesia.

Brain free fatty acids (FFAs) and brain water content were measured in gerbils subjected to transient, bilateral cerebral ischemia under brief halothane anesthesia (nontreated group) and pentobarbital anesthesia (treated group). Mortality in the two groups was also evaluated. In nontreated animals, both saturated and mono- and polyunsaturated FFAs increased approximately 12-fold in total at the end of a 30-min period of ischemia; during recirculation, the level of free arachidonic acid dropped rapidly, while other FFAs gradually decreased to their preischemic levels in 90 min. In treated animals, the levels of total FFAs were lower than the nontreated group during ischemia, but higher at 90 min of reflow, and the decrease in the rate of free arachidonic acid was slower in the early period of reflow. Water content increased progressively during ischemia and recirculation with no extravasation of serum protein, but the values were consistently lower in the treated group. None of the nontreated animals survived for 2 weeks; in contrast, survival was 37.5% in the treated group. It is suggested that barbiturate protection from transient cerebral ischemia may be mediated by the attenuation of both membrane phospholipid hydrolysis during ischemia and postischemic peroxidation of accumulated free arachidonic acid.

Anesthesia, General↗
PubMed1985

Induction of a cytochrome P-450-dependent fatty acid monooxygenase in Bacillus megaterium by a barbiturate analog, 1-[2-phenylbutyryl]-3-methylurea.

In previous publications from our laboratory, we reported that a soluble, cytochrome P-450-dependent fatty acid monooxygenase from Bacillus megaterium ATCC 14581 can be induced by phenobarbital and a variety of other barbiturates. The tested barbiturates showed an excellent correlation between increasing lipophilicity and increasing inducer potency (Kim BH, Fulco AJ; Biochem Biophys Res Commun 116: 843-850, 1983). The only exception proved to be mephobarbital (N-methylphenobarbital) which, although more lipophilic than phenobarbital, is not an inducer of fatty acid monooxygenase activity. We have now found that 1-[2-phenylbutyryl]-3-methylurea (PBMU), an acylurea that can be derived from mephobarbital by hydrolytic cleavage of the barbiturate ring, is an excellent inducer of this activity. Paradoxically, the addition of mephobarbital to the bacterial growth medium containing PBMU significantly enhances the apparent potency of the acylurea to induce fatty acid monooxygenase activity as measured in cell-free extracts. When cell-free extracts of cells grown separately in PBMU or mephobarbital are mixed no enhancement of activity is seen. This finding suggests that the effect of mephobarbital is to somehow increase the efficiency of PBMU as an inducer of the P-450-dependent fatty acid monooxygenase rather than to induce an activator of this enzyme or a rate-limiting component of the monooxygenase system. Finally, both mephobarbital and PBMU induce the synthesis of total cytochrome P-450 in B. megaterium although PBMU is a much more potent P-450 inducer. For cytochrome P-450 induction, however, there is no synergistic or even additive effect when mephobarbital and PBMU are used together in the bacterial growth medium.

Bacillus megaterium↗
PubMed1986

Anesthetic and convulsant barbiturates alter gamma-aminobutyric acid-stimulated chloride flux across brain membranes.

gamma-Aminobutyric acid (GABA), the major inhibitory neurotransmitter in the mammalian brain, increases membrane chloride conductance. Previously, the authors reported that GABA increases 36Cl- uptake by membrane vesicles (microsacs) prepared from mouse brain. In the present study, we examined the actions of barbiturates on basal and GABA-stimulated chloride influx by brain vesicles. The anesthetic barbiturates pentobarbital, phenobarbital, mephobarbital, amobarbital, hexobarbital and R-(-)-1-methyl-5-phenyl-5-propyl barbiturate enhanced GABA-dependent chloride flux. Barbiturate enhancement of GABA action was seen at concentrations that are subanesthetic in vivo (e.g., 10 microM pentobarbital was effective). Pentobarbital was about 10 times more potent than pentobarbital, suggesting that chloride flux is related to the sedative rather than anticonvulsant actions of barbiturates. Pentobarbital (1 mM) prevented the antagonism of GABA-stimulated 36Cl- produced by picrotoxinin. The barbiturates generally produced no change in GABA-independent flux, although large concentrations of pentobarbital or hexobarbital produced a slight enhancement of chloride flux in the absence of GABA. The convulsant barbiturate S-(+)-1-methyl-5-phenyl-5-propyl barbiturate inhibited GABA-stimulated chloride flux, an action opposite to that of its anesthetic enantiomer. These experiments provide evidence for a functional coupling among GABA and barbiturate receptors and the chloride ionophore and suggest that the GABA-activated chloride channel is a site of action for intoxicant-anesthetic and convulsant barbiturates.

Animals↗
PubMed2004

[Efficacy and safety of antiepileptic therapy in children (a comparative analysis of valproates and barbiturates)].

The study aimed at a comparative analysis of safety and efficacy of valproic acid (valproate) and barbiturates in the treatment of epilepsy in children. Two hundred and forty children were treated with valproate, 94% being assigned to depakine and depakine chrono, and 210 children received barbiturates. Therapeutic effect (a decrease of seizures frequency by 2 and more times or remission) was detected in 82 of 127 (65 +/- 8.53%) patients for valproate monotherapy and only in 26 of 89 (30 +/- 9.45%) for barbiturates monotherapy. An efficacy of antiepileptic therapy in children was significantly higher (p<0.05) for valproates as compared to barbiturates. A drug withdrawal due to poor tolerability was recorded in 6 of 127 (5 +/- 3.7%) patients treated with valproate in monotherapy and in 14 of 210 (7 +/- 3.45%)--in polytherapy; in 53 of 89 (59 +/- 10.2%) patients treated with barbiturates in monotherapy and in 78 of 121 (65 +/- 8.53%) patients treated with barbiturates in polytherapy. Therefore, adverse effects occurred more often in barbiturates than in valproate treatment both for mono- and polytherapy (p<0.05). The results of the study confirmed the high efficacy and safety of valproates, specifically depakine chrono, in the treatment of epilepsy in children. depakine chrono in-take is associated with lower frequency of adverse effects; side-effects are mostly of dose-dependent character and do not result in the drug withdrawal. The authors do not recommend using barbiturates in the first-line treatment in children, because of the lower efficacy, high frequency of medical complications that might result in the drug withdrawal and reducing of the efficacy of other antiepileptic medications.

Adolescent↗
PubMed1989

Steroid anesthetics and naturally occurring analogs modulate the gamma-aminobutyric acid receptor complex at a site distinct from barbiturates.

The steroid anesthetic alphaxalone and a series of naturally occurring analogs were compared in potency and efficacy with each other and the hypnotic barbiturate pentobarbital for interaction with gamma-aminobutyric acid (GABA) receptors:binding sites in rat brain membranes and functional activity in 36Cl- flux measurements with rat hippocampal slices. The steroids enhanced [3H]muscimol binding to GABA receptor sites, enhanced [3H] flunitrazepam binding to benzodiazepine receptors and inhibited [35S]t-butyl bicyclophosphorothionate binding to picrotoxin/convulsant binding sites on the GABA receptor-chloride channel complex. The same steroids that were active in modulating the binding of ligands to the various receptor sites on the GABA receptor complex at micromolar concentrations enhanced muscimol-stimulated 36Cl- flux in rat hippocampal slices. The steroids, like the barbiturates, increased the maximal response to muscimol but produced little or no potentiation of basal 36Cl- flux in the absence of GABA agonist. Although the effects of steroids and barbiturates were similar, separate sites of action were demonstrated conclusively by the observation that the two classes of compounds, when included together, gave additive or synergistic effects on binding, as well as on 36Cl- flux in the absence of GABA agonist. Structure-activity studies showed that the synthetic steroid anesthetic alphaxalone was the most potent compound tested, followed by the naturally occurring steroids tetrahydro-deoxycorticosterone, allo-tetrahydrocorticosterone, cis-androsterone and 5 alpha-androstan-17 beta-ol-3-one. The ability of several naturally occurring steroids to enhance GABA-mediated inhibition in the brain suggests the possibility of an endogenous steroid modulator of neuronal function.

Anesthetics↗
PubMed1978

Inhibition of gamma-aminobutyric acid release from rat cerebral cortex slices by barbiturate anesthesia.

Amobarbital and pentobarbital anesthesia inhibited the potassium-stimulated, Ca-dependent release of gamma-aminobutyric acid (GABA) from rat cerebral cortex slices during incubation in vitro. Inhibition of GABA release was not found when slices were prepared from rats shortly after they awakened from amobarbital anesthesia. Phenobarbital anesthesia did not affect the release of GABA.

Amino Acids↗