Adrenergic Stimulation of Na/K Pump Current in Adult Rat Cardiac Myocytes in Short-term Culture

1998 ◽  
Vol 163 (3) ◽  
pp. 205-216 ◽  
Author(s):  
J.R. Stimers ◽  
M. Dobretsov
Keyword(s):  
Cardiac Myocytes ◽  
Pump Current ◽  
Adrenergic Stimulation ◽  
Short Term ◽  
Adult Rat ◽  
Rat Cardiac Myocytes ◽  
Short Term Culture ◽  
Stimulation Of

scholarly journals Na+-K+pump cycle during β-adrenergic stimulation of adult rat cardiac myocytes

1998 ◽  
Vol 507 (2) ◽  
pp. 527-539 ◽  
Author(s):  
Maxim Dobretsov ◽  
Stephanie L. Hastings ◽  
Joseph R. Stimers
Keyword(s):  
Cardiac Myocytes ◽  
Adrenergic Stimulation ◽  
Adult Rat ◽  
Rat Cardiac Myocytes ◽  
Stimulation Of

Effect of Napip on K0 activation of the Na-K pump in adult rat cardiac myocytes

1994 ◽  
Vol 266 (1) ◽  
pp. C37-C41 ◽  
Author(s):  
T. A. Kinard ◽  
X. Y. Liu ◽  
S. Liu ◽  
J. R. Stimers
Keyword(s):  
Environmental Factors ◽  
Cardiac Myocytes ◽  
Pump Current ◽  
Apparent Affinity ◽  
Adult Rat ◽  
Cyclic Model ◽  
Pump Activity ◽  
Dose Dependent ◽  
Rat Cardiac Myocytes ◽  
External K

To determine if environmental factors influence the external K (K0) dependence of Na-K pump current (Ip), we systematically varied internal (pipette) Na (Napip) and Na-K pump activity while measuring the K0 dependence in adult rat cardiac myocytes. For each Napip, reactivation of Ip by K0 was dose dependent. The maximal Ip (Ipmax) and apparent affinity for K0 binding to the Na-K pump (K0.5) increased as Napip increased. The results of making an equimolar substitution of tetramethylammonium for K and Cs, and partial Ip inhibition with ouabain, also showed that Ipmax and K0.5 increased as Napip increased. We simulated pump activity as a function of intracellular Na (Nai) and K0 using a cyclic model of the Na-K pump and found that the model predicts K0.5 for K0 binding increases as Na increases, even when the conditions are adjusted by removing pipette K and partial pump inhibition with ouabain.

scholarly journals Phospholemman overexpression inhibits Na+-K+-ATPase in adult rat cardiac myocytes: relevance to decreased Na+ pump activity in postinfarction myocytes

2006 ◽  
Vol 100 (1) ◽  
pp. 212-220 ◽  
Author(s):  
Xue-Qian Zhang ◽  
J. Randall Moorman ◽  
Belinda A. Ahlers ◽  
Lois L. Carl ◽  
Douglas E. Lake ◽  
...  
Keyword(s):  
Atpase Activity ◽  
Cardiac Myocytes ◽  
Messenger Rna ◽  
Fluorescent Protein ◽  
Pump Current ◽  
Relative Level ◽  
Adult Rat ◽  
Rat Myocytes ◽  
Rat Cardiac Myocytes ◽  
Rna Levels

Messenger RNA levels of phospholemman (PLM), a member of the FXYD family of small single-span membrane proteins with putative ion-transport regulatory properties, were increased in postmyocardial infarction (MI) rat myocytes. We tested the hypothesis that the previously observed reduction in Na+-K+-ATPase activity in MI rat myocytes was due to PLM overexpression. In rat hearts harvested 3 and 7 days post-MI, PLM protein expression was increased by two- and fourfold, respectively. To simulate increased PLM expression post-MI, PLM was overexpressed in normal adult rat myocytes by adenovirus-mediated gene transfer. PLM overexpression did not affect the relative level of phosphorylation on serine68 of PLM. Na+-K+-ATPase activity was measured as ouabain-sensitive Na+-K+ pump current (Ip). Compared with control myocytes overexpressing green fluorescent protein alone, Ip measured in myocytes overexpressing PLM was significantly ( P < 0.0001) lower at similar membrane voltages, pipette Na+ ([Na+]pip) and extracellular K+ ([K+]o) concentrations. From −70 to +60 mV, neither [Na+]pip nor [K+]o required to attain half-maximal Ip was significantly different between control and PLM myocytes. This phenotype of decreased Vmax without appreciable changes in Km for Na+ and K+ in PLM-overexpressed myocytes was similar to that observed in MI rat myocytes. Inhibition of Ip by PLM overexpression was not due to decreased Na+-K+-ATPase expression because there were no changes in either protein or messenger RNA levels of either α1- or α2-isoforms of Na+-K+-ATPase. In native rat cardiac myocytes, PLM coimmunoprecipitated with α-subunits of Na+-K+-ATPase. Inhibition of Na+-K+-ATPase by PLM overexpression, in addition to previously reported decrease in Na+-K+-ATPase expression, may explain altered Vmax but not Km of Na+-K+-ATPase in postinfarction rat myocytes.

scholarly journals NO donors potentiate the β‐adrenergic stimulation of I Ca,L and the muscarinic activation of I K,ACh in rat cardiac myocytes

2002 ◽  
Vol 540 (2) ◽  
pp. 411-424 ◽  
Author(s):  
Najah Abi‐Gerges ◽  
Gabor Szabo ◽  
Angela S. Otero ◽  
Rodolphe Fischmeister ◽  
Pierre‐François Méry
Keyword(s):  
Cardiac Myocytes ◽  
Adrenergic Stimulation ◽  
No Donors ◽  
Rat Cardiac Myocytes ◽  
Stimulation Of
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