Biomaterial Database

Effects of therapeutic concentrations of diphenylhydantoin on transmembrane potentials of normal and depressed Purkinje fibers. 1976

M R Rosen, and P Danilo, and M B Alonso, and C E Pippenger

Standard intracellular microelectrode techniques were used to study canine Purkinje fibers (PF) which had been superfused with blood or Tyrode's solution to determine the cardiac cellular electrophysiologic changes induced by antiarrhythmic concentrations of diphenylhydantoin (DPH). Some PF were normal whereas others were depressed by stretch, exposure to ouabain (125 mug/1) or superfusion with a solution in which all Na+ was replaced by tetraethylammonium. For normal fibers, therapeutic concentrations of DPH (DPH) induced slight decreases in action potential (AP) amplitude, maximum upstroke velocity of phase O (Vmax) and membrane responsiveness and somewhat greater decreases in AP duration. For fibers moderately depressed by ouabain or stretch, with reduced AP amplitude, maximum diastolic potential and Vmax, therapeutic [DPH] increased these variables. Fibers markedly depressed by Na-free solution or stretch developed slow response AP. The amplitude and Vmax of the AP were decreased by therapeutic [DPH]. Therapeutic [DPH] also suppressed automaticity and ouabain-induced delayed afterdepolarizations. Our studies suggest that the slight depression of normal PF AP characteristics induced by therapeutic [DPH] probably is of little significance with respect to antiarrhythmic effect. In contrast, both the improvement of AP characteristics of moderately depressed fibers and further depression of severely depressed fibers caused by [DPH] might modify arrhythmias. Effects of DPH on automaticity and delayed afterdepolarizations also would contribute to its antiarrhythmic effect.

UI	MeSH Term	Description	Entries
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
D010042	Ouabain	A cardioactive glycoside consisting of rhamnose and ouabagenin, obtained from the seeds of Strophanthus gratus and other plants of the Apocynaceae; used like DIGITALIS. It is commonly used in cell biological studies as an inhibitor of the NA(+)-K(+)-EXCHANGING ATPASE.	Acocantherin,G-Strophanthin,Acolongifloroside K,G Strophanthin
D010477	Perfusion	Treatment process involving the injection of fluid into an organ or tissue.	Perfusions
D010672	Phenytoin	An anticonvulsant that is used to treat a wide variety of seizures. It is also an anti-arrhythmic and a muscle relaxant. The mechanism of therapeutic action is not clear, although several cellular actions have been described including effects on ion channels, active transport, and general membrane stabilization. The mechanism of its muscle relaxant effect appears to involve a reduction in the sensitivity of muscle spindles to stretch. Phenytoin has been proposed for several other therapeutic uses, but its use has been limited by its many adverse effects and interactions with other drugs.	Diphenylhydantoin,Fenitoin,Phenhydan,5,5-Diphenylhydantoin,5,5-diphenylimidazolidine-2,4-dione,Antisacer,Difenin,Dihydan,Dilantin,Epamin,Epanutin,Hydantol,Phenytoin Sodium,Sodium Diphenylhydantoinate,Diphenylhydantoinate, Sodium
D010949	Plasma	The residual portion of BLOOD that is left after removal of BLOOD CELLS by CENTRIFUGATION without prior BLOOD COAGULATION.	Blood Plasma,Fresh Frozen Plasma,Blood Plasmas,Fresh Frozen Plasmas,Frozen Plasma, Fresh,Frozen Plasmas, Fresh,Plasma, Blood,Plasma, Fresh Frozen,Plasmas,Plasmas, Blood,Plasmas, Fresh Frozen
D011690	Purkinje Fibers	Modified cardiac muscle fibers composing the terminal portion of the heart conduction system.	Purkinje Fiber,Fiber, Purkinje,Fibers, Purkinje
D004285	Dogs	The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065)	Canis familiaris,Dog
D006329	Heart Conduction System	An impulse-conducting system composed of modified cardiac muscle, having the power of spontaneous rhythmicity and conduction more highly developed than the rest of the heart.	Conduction System, Heart,Conduction Systems, Heart,Heart Conduction Systems,System, Heart Conduction,Systems, Heart Conduction
D000200	Action Potentials	Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.	Spike Potentials,Nerve Impulses,Action Potential,Impulse, Nerve,Impulses, Nerve,Nerve Impulse,Potential, Action,Potential, Spike,Potentials, Action,Potentials, Spike,Spike Potential
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