Francisco Cuevas | Universidad Santo Tomás (original) (raw)

Papers by Francisco Cuevas

Research paper thumbnail of The Antiepileptic Drug Diphenylhydantoin Affects the Structure of the Human Erythrocyte Membrane

Zeitschrift für Naturforschung C, 2004

Phenytoin (diphenylhydantoin) is an antiepileptic agent effective against all types of partial an... more Phenytoin (diphenylhydantoin) is an antiepileptic agent effective against all types of partial and tonic-clonic seizures. Phenytoin limits the repetitive firing of action potentials evoked by a sustained depolarization of mouse spinal cord neurons maintained in vitro. This effect is mediated by a slowing of the rate of recovery of voltage activated Na+ channels from inactivation. For this reasons it was thought of interest to study the binding affinities of phenytoin with cell membranes and their perturbing effects upon membrane structures. The effects of phenytoin on the human erythrocyte membrane and molecular models have been investigated in the present work. This report presents the following evidence that phenytoin interacts with cell membranes: a) X-ray diffraction and fluorescence spectroscopy of phospholipid bilayers showed that phenytoin perturbed a class of lipids found in the outer moiety of cell membranes; b) in isolated unsealed human erythrocyte membranes (IUM) the dru...

Research paper thumbnail of Dibucaine-Induced Modification of Sodium Transport in Toad Skin and of Model Membrane Structures

Zeitschrift für Naturforschung C, 2001

The interaction of the local anesthetic dibucaine with the isolated toad skin and membrane models... more 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 (DMPE), 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 multil...

Research paper thumbnail of Modulation of Pig Kidney Na + /K + -ATPase Activity by Cholesterol:  Role of Hydration †

Research paper thumbnail of The local anesthetic proparacaine modifies sodium transport in toad skin and perturbs the structures of model and cell membranes

… fur Naturforschung C …, 2002

Experimental results indicate a significant decrease in the potential difference (PD) and in the ... more Experimental results indicate a significant decrease in the potential difference (PD) and in the short-circuit current (Isc) after the application of proparacaine to isolated toad skin, which may reflect an inhibition of the active transport of ions. This finding was explained on the basis of the results obtained from membrane models incubated with proparacaine. These consisted of human erythrocytes, isolated unsealed human erythrocyte membranes (IUM), phospholipid multilayers built-up of dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylethanolamine (DMPE), representatives of phospholipid classes located in the outer and inner monolayers of the human erythrocyte membrane, respectively, and in large unilamellar vesicles (LUV) of DMPC. X-ray diffraction showed that proparacaine interaction with DMPC and DMPE bilayers perturbed both structures, especially DMPC. This result, confirmed by fluorescence spectroscopy of DMPC LUV at 18 ∞C, demonstrated that the local anesthetic (LA) could interact with the lipid moiety of cell membranes. However, effects observed by scanning electron microscopy (SEM) of human erythrocytes and by fluorescence spectroscopy of IUM might also imply proparacaine-protein interactions. Thus, the LA may alter epithelial sodium channels through interaction with the lipid matrix and with channel protein residues.

Research paper thumbnail of The Antiepileptic Drug Diphenylhydantoin Affects the Structure of the Human Erythrocyte Membrane

Zeitschrift für Naturforschung C, 2004

Phenytoin (diphenylhydantoin) is an antiepileptic agent effective against all types of partial an... more Phenytoin (diphenylhydantoin) is an antiepileptic agent effective against all types of partial and tonic-clonic seizures. Phenytoin limits the repetitive firing of action potentials evoked by a sustained depolarization of mouse spinal cord neurons maintained in vitro. This effect is mediated by a slowing of the rate of recovery of voltage activated Na+ channels from inactivation. For this reasons it was thought of interest to study the binding affinities of phenytoin with cell membranes and their perturbing effects upon membrane structures. The effects of phenytoin on the human erythrocyte membrane and molecular models have been investigated in the present work. This report presents the following evidence that phenytoin interacts with cell membranes: a) X-ray diffraction and fluorescence spectroscopy of phospholipid bilayers showed that phenytoin perturbed a class of lipids found in the outer moiety of cell membranes; b) in isolated unsealed human erythrocyte membranes (IUM) the dru...

Research paper thumbnail of Dibucaine-Induced Modification of Sodium Transport in Toad Skin and of Model Membrane Structures

Zeitschrift für Naturforschung C, 2001

The interaction of the local anesthetic dibucaine with the isolated toad skin and membrane models... more 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 (DMPE), 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 multil...

Research paper thumbnail of Modulation of Pig Kidney Na + /K + -ATPase Activity by Cholesterol:  Role of Hydration †

Research paper thumbnail of The local anesthetic proparacaine modifies sodium transport in toad skin and perturbs the structures of model and cell membranes

… fur Naturforschung C …, 2002

Experimental results indicate a significant decrease in the potential difference (PD) and in the ... more Experimental results indicate a significant decrease in the potential difference (PD) and in the short-circuit current (Isc) after the application of proparacaine to isolated toad skin, which may reflect an inhibition of the active transport of ions. This finding was explained on the basis of the results obtained from membrane models incubated with proparacaine. These consisted of human erythrocytes, isolated unsealed human erythrocyte membranes (IUM), phospholipid multilayers built-up of dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylethanolamine (DMPE), representatives of phospholipid classes located in the outer and inner monolayers of the human erythrocyte membrane, respectively, and in large unilamellar vesicles (LUV) of DMPC. X-ray diffraction showed that proparacaine interaction with DMPC and DMPE bilayers perturbed both structures, especially DMPC. This result, confirmed by fluorescence spectroscopy of DMPC LUV at 18 ∞C, demonstrated that the local anesthetic (LA) could interact with the lipid moiety of cell membranes. However, effects observed by scanning electron microscopy (SEM) of human erythrocytes and by fluorescence spectroscopy of IUM might also imply proparacaine-protein interactions. Thus, the LA may alter epithelial sodium channels through interaction with the lipid matrix and with channel protein residues.