%0 Journal Article %1 Webe_2002_182 %A Weber, Christopher R %A Piacentino, Valentino %A Ginsburg, Kenneth S %A Houser, Steven R %A Bers, Donald M %D 2002 %J Circ. Res. %K 11834700 ATPase, Action Adenocarcinoma, Adult, Allosteric Animal, Animals, Blockers, Calcium, Cell Cells, Channel Channels, Congestive, Contraction, Diastole, Disease Electric Electrophysiology, Esophageal Exchanger, Failure, Fatal Fluid, Gov't, Guinea Heart Heart, Humans, In Intracellular Ion Kinetics, Male, Maxillary Membrane Membrane, Models, Muscle Myocardial Myocardium, Neoplasms, Nickel, Non-U.S. Outcome, P.H.S., Patch-Clamp Pigs, Potentia, Potentials, Rabbits, Re, Regulation, Research Reticulum, Sarcoplasmic Separation, So, Sodium Sodium, Sodium-Calcium Stimulation, Strophanthidin, Support, Techniques, Tetrodotoxin, Transport, U.S. Ventricles, Vitro, dium-Calcium ls, search {N}a$^{+}$-{K}$^{+}$-Exchanging %N 2 %P 182--189 %T Na$^+$-Ca$^2+$ exchange current and submembrane Ca$^2+$ during the cardiac action potential. %U http://circres.ahajournals.org/cgi/content/full/90/2/182 %V 90 %X Na$^+$-Ca$^2+$ exchange (NCX) is crucial in the regulation of Ca$^2+$(i) and cardiac contractility, but key details of its dynamic function during the heartbeat are not known. In the present study, we assess how NCX current (I(NCX)) varies during a rabbit ventricular action potential (AP). First, we measured the steady-state voltage and Ca$^2+$(i) dependence of I(NCX) under conditions when Ca$^2+$(i) was heavily buffered. We then used this relationship to infer the submembrane Ca$^2+$(i) (Ca$^2+$(sm)) sensed by NCX during a normal AP and Ca$^2+$(i) transient (when the AP was interrupted to produce an I(NCX) tail current). The Ca$^2+$(i) dependence of I(NCX) at -90 mV allowed us to convert the peak inward I(NCX) tail currents to Ca$^2+$(sm). Peak Ca$^2+$(sm) measured via this technique was >3.2 micromol/L within < 32 ms of the AP upstroke (versus peak Ca$^2+$(i) of 1.1 micromol/L at 81 ms measured with the global Ca$^2+$ indicator indo-1). The voltage and Ca$^2+$(sm) dependence of I(NCX) allowed us to infer I(NCX) during the normal AP and Ca$^2+$ transient. The early rise in Ca$^2+$(sm) causes I(NCX) to be inward for the majority of the AP. Thus, little Ca$^2+$ influx via NCX is expected under physiological conditions, but this can differ among species and in pathophysiological conditions.

@article{Webe_2002_182, abstract = {{N}a$^{+}$-{C}a$^{2+}$ exchange (NCX) is crucial in the regulation of [{C}a$^{2+}$](i) and cardiac contractility, but key details of its dynamic function during the heartbeat are not known. In the present study, we assess how NCX current (I(NCX)) varies during a rabbit ventricular action potential (AP). First, we measured the steady-state voltage and [{C}a$^{2+}$](i) dependence of I(NCX) under conditions when [{C}a$^{2+}$](i) was heavily buffered. We then used this relationship to infer the submembrane [{C}a$^{2+}$](i) ([{C}a$^{2+}$](sm)) sensed by NCX during a normal AP and [{C}a$^{2+}$](i) transient (when the AP was interrupted to produce an I(NCX) tail current). The [{C}a$^{2+}$](i) dependence of I(NCX) at -90 mV allowed us to convert the peak inward I(NCX) tail currents to [{C}a$^{2+}$](sm). Peak [{C}a$^{2+}$](sm) measured via this technique was >3.2 micromol/L within < 32 ms of the AP upstroke (versus peak [{C}a$^{2+}$](i) of 1.1 micromol/L at 81 ms measured with the global {C}a$^{2+}$ indicator indo-1). The voltage and [{C}a$^{2+}$](sm) dependence of I(NCX) allowed us to infer I(NCX) during the normal AP and {C}a$^{2+}$ transient. The early rise in [{C}a$^{2+}$](sm) causes I(NCX) to be inward for the majority of the AP. Thus, little {C}a$^{2+}$ influx via NCX is expected under physiological conditions, but this can differ among species and in pathophysiological conditions.}, added-at = {2009-06-03T11:20:58.000+0200}, author = {Weber, Christopher R and Piacentino, Valentino and Ginsburg, Kenneth S and Houser, Steven R and Bers, Donald M}, biburl = {https://www.bibsonomy.org/bibtex/2846a6b89468e1cab89d34423c613fdee/hake}, description = {The whole bibliography file I use.}, file = {Webe_2002_182.pdf:Webe_2002_182.pdf:PDF}, interhash = {ef429b3940a2db63313f07d69ee55fae}, intrahash = {846a6b89468e1cab89d34423c613fdee}, journal = {Circ. Res.}, key = 151, keywords = {11834700 ATPase, Action Adenocarcinoma, Adult, Allosteric Animal, Animals, Blockers, Calcium, Cell Cells, Channel Channels, Congestive, Contraction, Diastole, Disease Electric Electrophysiology, Esophageal Exchanger, Failure, Fatal Fluid, Gov't, Guinea Heart Heart, Humans, In Intracellular Ion Kinetics, Male, Maxillary Membrane Membrane, Models, Muscle Myocardial Myocardium, Neoplasms, Nickel, Non-U.S. Outcome, P.H.S., Patch-Clamp Pigs, Potentia, Potentials, Rabbits, Re, Regulation, Research Reticulum, Sarcoplasmic Separation, So, Sodium Sodium, Sodium-Calcium Stimulation, Strophanthidin, Support, Techniques, Tetrodotoxin, Transport, U.S. Ventricles, Vitro, dium-Calcium ls, search {N}a$^{+}$-{K}$^{+}$-Exchanging}, month = Feb, number = 2, pages = {182--189}, pmid = {11834700}, timestamp = {2009-06-03T11:21:37.000+0200}, title = {{N}a$^{+}$-{C}a$^{2+}$ exchange current and submembrane [{C}a$^{2+}$] during the cardiac action potential.}, url = {http://circres.ahajournals.org/cgi/content/full/90/2/182}, volume = 90, year = 2002 }