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2001 (1)
1991 (1)
1Author    Mario Suwalsky3, Carlos Schneider3, Fernando Villenab, Beryl Norrisb, HernanC. Árdenasb, Francisco Cuevasc, CarlosP. SotomayorcRequires cookie*
 Title    Dibucaine-Induced Modification of Sodium Transport in Toad Skin and of Model Membrane Structures  
 Abstract    The interaction of the local anesthetic dibucaine with the isolated toad skin and membrane models is described. The latter consisted of human erythrocytes, isolated unsealed human erythrocyte membranes (IUM), large unilamellar vesicles (LUV) of dimyristoylphosphati-dylcholine (DMPC) and phospholipid multilayers built-up of DMPC and dimyristoylphos-phatidylethanolamine (D M PE), representative of phospholipid classes located in the outer and inner monolayers of the human erythrocyte membrane, respectively. Results indicate a significant decrease in the potential difference (PD) and in the short-circuit current (Isc) after the application of dibucaine in toad skin, which may be interpreted as reflecting inhibition of the active transport of ions. This finding might be explained on the basis of the results ob­ tained from fluorescence spectroscopy and X-ray diffraction studies on membrane models. In fact, dibucaine induced structural perturbations in IUM, DMPC LUV and phospholipid multilayers. Scanning electron microscopy revealed that dibucaine induced erythrocyte sto-matocytosis. According to the bilayer couple hypothesis an echinocytic type of shape change would have been expected given the preferential interaction of dibucaine with DMPC. Al­ though it is still premature to define the molecular mechanism of action of dibucaine, the experimental results confirm the important role played by the phospholipid bilayers in the association of the anesthetic with cell membranes. 
  Reference    Z. Naturforsch. 56c, 614 (2001); received January 29/March 8 2001 
  Published    2001 
  Keywords    Local Anesthetic, Dibucaine, Membrane 
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 TEI-XML for    default:Reihe_C/56/ZNC-2001-56c-0614.pdf 
 Identifier    ZNC-2001-56c-0614 
 Volume    56 
2Author    GabrieleG. Ünther, Henrik LaaschRequires cookie*
 Title    Local Anesthetic Binding to Thylakoid Membranes. Relation to Inhibition of Light-Induced Membrane Energization and Photophosphorylation  
 Abstract    The association o f the lipophilic tertiary amine and local anesthetic dibucaine with osm oti-cally shocked chloroplasts o f Spinacia oleracea L. cv. M onatol was investigated. Dibucaine, known as an effective inhibitor o f thylakoid membrane energization and A TP synthesis, ex­ hibited three distinct binding classes with chloroplasts: partitioning in the lipid phase o f the membranes, electrostatic screening o f negative electrical charges on the thylakoid surface and light-induced association o f an as yet unknown nature. Evidence is presented that the mecha­ nism o f inhibition o f the transthylakoid pH gradient, ApH, by dibucaine is distinct from 'clas­ sical' amine-type uncoupling: The inhibitory effect o f dibucaine on ApH was independent o f the initial strength o f ApH. Light-induced dibucaine binding was independent o f the volum e o f the intrathylakoid space and o f the strength o f ApH as varied by medium pH. Judged from a comparison o f the data on dibucaine binding and on inhibition o f ApH and photophosphory­ lation, dibucaine bound via partitioning in the membrane lipid phase is responsible for the un-coupler-like effects o f the local anesthetic. A mechanism for the inhibition o f thylakoid energi­ zation by local anesthetic amines is discussed. 
  Reference    Z. Naturforsch. 46c, 79—8 (1991); received September 21 1990 
  Published    1991 
  Keywords    Chloroplast, Local Anesthetic, Dibucaine, Uncoupling, Photophosphorylation, Amine Bind­ ing 
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 TEI-XML for    default:Reihe_C/46/ZNC-1991-46c-0079.pdf 
 Identifier    ZNC-1991-46c-0079 
 Volume    46