Effect of 2,6-diisopropylphenol and halogenated anesthetics on tetraphenylphosphonium uptake by rat brain synaptosomes: determination of membrane potential. 1999

M Marian, and A Bindoli, and F Callegarin, and M P Rigobello, and E Vincenti, and M Bragadin, and G Scutari
Department of Biological Chemistry, University of Padova, Italy.

The effect of 2,6-diisopropylphenol (propofol) in comparison to that of the halogenated anesthetics enflurane, isoflurane, and halothane on tetrapenylphosphonium uptake by rat brain synaptosomes was studied. A direct method to separately measure the synaptosomal and the mitochondrial transmembrane potential by using the tetraphenylphosphonium cation (TPP+) was utilized. The latter is a lipophylic charged molecule which distributes between two compartments according to the transmembrane electrical potential in the presence or absence of 60 mM KCl as a synaptosomal membrane depolarizing agent. After previously reporting the damages induced by general anesthetics on isolated mitochondria, the aim of this paper was to study their possible action on the synaptosomal membrane potential and whether or not drugs concentrations damaging isolated mitochondria are also effective on synaptosomal mitochondria. The results indicated that, in the presence of glucose, mitochondria included in synaptosomes were able to maintain a transmembrane potential of 202+/-8 mV (mean +/- SD) while the synaptosomal membrane showed a potential of 78+/-8 mV (mean +/- SD). When anesthetic concentrations (0.6-1 mM propofol, 10-40 microM enflurane, 30-50 microM isoflurane, 8-15 microM halothane) that impair mitochondrial energy metabolism were used, the synaptosomal transmembrane potential was maintained and, in addition, a slight increase of the TPP+ taken up was observed as the anesthetic concentration was increased.

UI MeSH Term Description Entries
D007530 Isoflurane A stable, non-explosive inhalation anesthetic, relatively free from significant side effects.
D008564 Membrane Potentials The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization). Resting Potentials,Transmembrane Potentials,Delta Psi,Resting Membrane Potential,Transmembrane Electrical Potential Difference,Transmembrane Potential Difference,Difference, Transmembrane Potential,Differences, Transmembrane Potential,Membrane Potential,Membrane Potential, Resting,Membrane Potentials, Resting,Potential Difference, Transmembrane,Potential Differences, Transmembrane,Potential, Membrane,Potential, Resting,Potential, Transmembrane,Potentials, Membrane,Potentials, Resting,Potentials, Transmembrane,Resting Membrane Potentials,Resting Potential,Transmembrane Potential,Transmembrane Potential Differences
D009861 Onium Compounds Ions with the suffix -onium, indicating cations with coordination number 4 of the type RxA+ which are analogous to QUATERNARY AMMONIUM COMPOUNDS (H4N+). Ions include phosphonium R4P+, oxonium R3O+, sulfonium R3S+, chloronium R2Cl+ Compounds, Onium
D009943 Organophosphorus Compounds Organic compounds that contain phosphorus as an integral part of the molecule. Included under this heading is broad array of synthetic compounds that are used as PESTICIDES and DRUGS. Organophosphorus Compound,Organopyrophosphorus Compound,Organopyrophosphorus Compounds,Compound, Organophosphorus,Compound, Organopyrophosphorus,Compounds, Organophosphorus,Compounds, Organopyrophosphorus
D001921 Brain The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM. Encephalon
D004737 Enflurane An extremely stable inhalation anesthetic that allows rapid adjustments of anesthesia depth with little change in pulse or respiratory rate. Alyrane,Enfran,Enlirane,Ethrane,Etran
D006221 Halothane A nonflammable, halogenated, hydrocarbon anesthetic that provides relatively rapid induction with little or no excitement. Analgesia may not be adequate. NITROUS OXIDE is often given concomitantly. Because halothane may not produce sufficient muscle relaxation, supplemental neuromuscular blocking agents may be required. (From AMA Drug Evaluations Annual, 1994, p178) 1,1,1-Trifluoro-2-Chloro-2-Bromoethane,Fluothane,Ftorotan,Narcotan
D006846 Hydrocarbons, Halogenated Hydrocarbon compounds with one or more HYDROGEN atoms substituted with HALOGENS. Halogenated Hydrocarbons
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D013574 Synaptosomes Pinched-off nerve endings and their contents of vesicles and cytoplasm together with the attached subsynaptic area of the membrane of the post-synaptic cell. They are largely artificial structures produced by fractionation after selective centrifugation of nervous tissue homogenates. Synaptosome

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