The electrogenic Na+/HCO3- cotransport modulates resting membrane potential and action potential duration in cat ventricular myocytes. 2007

María C Villa-Abrille, and Martín G Vila Petroff, and Ernesto A Aiello
Centro de Investigaciones Cardiovasculares, Facultad de Ciencias Médicas, 60 y 120, La Plata 1900, Argentina.

Perforated whole-cell configuration of patch clamp was used to determine the contribution of the electrogenic Na+/HCO3- cotransport (NBC) on the shape of the action potential in cat ventricular myocytes. Switching from Hepes to HCO3- buffer at constant extracellular pH (pH(o)) hyperpolarized resting membrane potential (RMP) by 2.67 +/- 0.42 mV (n = 9, P < 0.05). The duration of action potential measured at 50% of repolarization time (APD50) was 35.8 +/- 6.8% shorter in the presence of HCO3- than in its absence (n = 9, P < 0.05). The anion blocker SITS prevented and reversed the HCO3- -induced hyperpolarization and shortening of APD. In addition, no HCO3- -induced hyperpolarization and APD shortening was observed in the absence of extracellular Na+. Quasi-steady-state currents were evoked by 8 s duration voltage-clamped ramps ranging from -130 to +30 mV. A novel component of SITS-sensitive current was observed in the presence of HCO3-. The HCO3- -sensitive current reversed at -87 +/- 5 mV (n = 7), a value close to the expected reversal potential of an electrogenic Na+/HCO3- cotransport with a HCO3-:Na+ stoichiometry ratio of 2: 1. The above results allow us to conclude that the cardiac electrogenic Na+/HCO3- cotransport has a relevant influence on RMP and APD of cat ventricular cells.

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
D002415 Cats The domestic cat, Felis catus, of the carnivore family FELIDAE, comprising over 30 different breeds. The domestic cat is descended primarily from the wild cat of Africa and extreme southwestern Asia. Though probably present in towns in Palestine as long ago as 7000 years, actual domestication occurred in Egypt about 4000 years ago. (From Walker's Mammals of the World, 6th ed, p801) Felis catus,Felis domesticus,Domestic Cats,Felis domestica,Felis sylvestris catus,Cat,Cat, Domestic,Cats, Domestic,Domestic Cat
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
D012856 4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid A non-penetrating amino reagent (commonly called SITS) which acts as an inhibitor of anion transport in erythrocytes and other cells. 4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid, Disodium Salt,SITS,SITS Disodium Salt,4 Acetamido 4' isothiocyanatostilbene 2,2' disulfonic Acid,Disodium Salt, SITS
D016276 Ventricular Function The hemodynamic and electrophysiological action of the HEART VENTRICLES. Function, Ventricular,Functions, Ventricular,Ventricular Functions
D018408 Patch-Clamp Techniques An electrophysiologic technique for studying cells, cell membranes, and occasionally isolated organelles. All patch-clamp methods rely on a very high-resistance seal between a micropipette and a membrane; the seal is usually attained by gentle suction. The four most common variants include on-cell patch, inside-out patch, outside-out patch, and whole-cell clamp. Patch-clamp methods are commonly used to voltage clamp, that is control the voltage across the membrane and measure current flow, but current-clamp methods, in which the current is controlled and the voltage is measured, are also used. Patch Clamp Technique,Patch-Clamp Technic,Patch-Clamp Technique,Voltage-Clamp Technic,Voltage-Clamp Technique,Voltage-Clamp Techniques,Whole-Cell Recording,Patch-Clamp Technics,Voltage-Clamp Technics,Clamp Technique, Patch,Clamp Techniques, Patch,Patch Clamp Technic,Patch Clamp Technics,Patch Clamp Techniques,Recording, Whole-Cell,Recordings, Whole-Cell,Technic, Patch-Clamp,Technic, Voltage-Clamp,Technics, Patch-Clamp,Technics, Voltage-Clamp,Technique, Patch Clamp,Technique, Patch-Clamp,Technique, Voltage-Clamp,Techniques, Patch Clamp,Techniques, Patch-Clamp,Techniques, Voltage-Clamp,Voltage Clamp Technic,Voltage Clamp Technics,Voltage Clamp Technique,Voltage Clamp Techniques,Whole Cell Recording,Whole-Cell Recordings
D027982 Sodium-Bicarbonate Symporters Proteins that cotransport sodium ions and bicarbonate ions across cellular membranes. SLC4A5 Protein,Electrogenic Sodium Bicarbonate Cotransporter 1,Electrogenic Sodium Bicarbonate Cotransporter 4,Electroneutral Na(+)-Driven Cl-HCO3 Exchanger,Electroneutral Sodium Bicarbonate Exchanger 1,NBC1 Protein,NBC3 Protein,NBC4 Protein,NBCE1 Protein,NBCe2 Protein,NBCn2 Protein,NCBE Protein,Na-HCO3 Symport,SLC4A10 Protein,SLC4A4 Protein,SLC4A7 Protein,SLC4A8 Protein,Sodium Bicarbonate Cotransporter 2,Sodium Bicarbonate Cotransporter 3,Sodium Bicarbonate Symport,Sodium-Bicarbonate Cotransporter,Sodium-Coupled Bicarbonate Transporters,Sodium-driven chloride bicarbonate exchanger,Solute Carrier Family 4 Member 10,Solute Carrier Family 4 Member 4,Solute Carrier Family 4 Member 5,Solute Carrier Family 4 Member 7,Solute Carrier Family 4 Member 8,Solute Carrier Family 4, Sodium Bicarbonate Cotransporter, Member 10,Solute Carrier Family 4, Sodium Bicarbonate Cotransporter, Member 4,Solute Carrier Family 4, Sodium Bicarbonate Cotransporter, Member 5,Solute Carrier Family 4, Sodium Bicarbonate Cotransporter, Member 7,Solute Carrier Family 4, Sodium Bicarbonate Cotransporter, Member 8,k-NBC3 Protein,Bicarbonate Symport, Sodium,Bicarbonate Transporters, Sodium-Coupled,Cotransporter, Sodium-Bicarbonate,Na HCO3 Symport,Protein, NBC1,Protein, NBC3,Protein, NBC4,Protein, NBCE1,Protein, NBCe2,Protein, NBCn2,Protein, SLC4A10,Protein, SLC4A4,Protein, SLC4A5,Protein, SLC4A7,Protein, SLC4A8,Protein, k-NBC3,Sodium Bicarbonate Cotransporter,Sodium Bicarbonate Symporters,Sodium Coupled Bicarbonate Transporters,Sodium driven chloride bicarbonate exchanger,Symport, Na-HCO3,Symport, Sodium Bicarbonate,Symporters, Sodium-Bicarbonate,Transporters, Sodium-Coupled Bicarbonate,k NBC3 Protein
D032383 Myocytes, Cardiac Striated muscle cells found in the heart. They are derived from cardiac myoblasts (MYOBLASTS, CARDIAC). Cardiomyocytes,Muscle Cells, Cardiac,Muscle Cells, Heart,Cardiac Muscle Cell,Cardiac Muscle Cells,Cardiac Myocyte,Cardiac Myocytes,Cardiomyocyte,Cell, Cardiac Muscle,Cell, Heart Muscle,Cells, Cardiac Muscle,Cells, Heart Muscle,Heart Muscle Cell,Heart Muscle Cells,Muscle Cell, Cardiac,Muscle Cell, Heart,Myocyte, Cardiac

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