The role of intracellular sodium ions in the Ca-paradox in isolated guinea-pig ventricular myocytes, as revealed by Na-sensitive micro-electrodes

This study investigated the role of the Na+/Ca2+ exchanger (NCX) in regulating cytosolic intracellular Ca2+concentration ([Ca2+]i) during anoxia/reoxygenation in guinea pig ventricular myocytes. The hypothesis that the NCX is the predominant mechanism mediating [Ca2+]i overload in this model was tested through inhibition of NCX expression by an antisense oligonucleotide. Immunocytochemistry revealed that this antisense oligonucleotide, directed at the area around the start site of the guinea pig NCX1, specifically reduced NCX expression in cultured adult myocytes by 90 ± 4%. Antisense treatment inhibited evoked NCX activity by 94 ± 3% and decreased the rise in [Ca2+]i during anoxia/reoxygenation by 95 ± 3%. These data suggest that NCX is the predominant mechanism mediating Ca2+ overload during anoxia/reoxygenation in guinea-pig ventricular myocytes.

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Effects of Endothelin-1 on Ca2+Signaling in Guinea-Pig Ventricular Myocytes: Role of Protein Kinase C

Journal of Molecular and Cellular Cardiology ◽

10.1006/jmcc.1998.0899 ◽

1999 ◽

Vol 31 (3) ◽

pp. 631-643 ◽

Cited By ~ 45

Author(s):

Sun Hee Woo ◽

Chin Ok Lee

Keyword(s):

Protein Kinase C ◽

Protein Kinase ◽

Guinea Pig ◽

Ventricular Myocytes ◽

Endothelin 1 ◽

Kinase C

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Role of sodium ions in angiotensin tachyphylaxis in the guinea-pig ileum and taenia coli

Naunyn-Schmiedeberg s Archives of Pharmacology ◽

10.1007/bf00175792 ◽

1988 ◽

Vol 337 (6) ◽

Cited By ~ 14

Author(s):

TherezinhaB. Paiva ◽

AntonioC.M. Paiva ◽

SumaI. Shimuta

Keyword(s):

Guinea Pig ◽

Taenia Coli ◽

Sodium Ions ◽

Guinea Pig Ileum

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On the mechanism of rectification of the isoproterenol-activated chloride current in guinea-pig ventricular myocytes.

The Journal of General Physiology ◽

10.1085/jgp.102.5.871 ◽

1993 ◽

Vol 102 (5) ◽

pp. 871-895 ◽

Cited By ~ 33

Author(s):

J L Overholt ◽

M E Hobert ◽

R D Harvey

Keyword(s):

Guinea Pig ◽

Ventricular Myocytes ◽

Reversal Potential ◽

Rate Theory ◽

Constant Field ◽

Patch Clamp Technique ◽

Site Model ◽

Outward Rectification ◽

Current Equation

The whole cell configuration of the patch clamp technique was used to investigate the mechanism underlying rectification of the isoproterenol-activated chloride (Cl-) current in isolated guinea pig ventricular myocytes. When extracellular Cl- was replaced with either bromide (Br-), glutamate (Glut), iodide (I-), isethionate (Iseth), or nitrate (NO3-), the magnitude of the shift in reversal potential of the macroscopic current suggested the following selectivity sequence: NO3- > Br- > or = Cl- > or = I- > Iseth > or = Glut. This information was used to investigate the role of permeant ions in rectification of this current. Consistent with previous observations, when the concentration of intracellular Cl- (Cli-) was less than the concentration of extracellular Cl- (Clo-) (40 mM Cli-/150 mM Clo-) the current exhibited outward rectification, but when Cli- was increased to equal that outside (150 Cli-/150 Clo-), the current no longer rectified. Rectification in the presence of asymmetrical concentrations of permeant ions on either side of the membrane is predicted by constant field theory, as described by the Goldman-Hodgkin-Katz current equation. However, when the Cl- gradient was reversed (150 Cli-/40 Clo-) the current did not rectify in the opposite direction, and in the presence of lower symmetrical concentrations of Cl- inside and out (40 Cli-/40 Clo-), outward rectification did not disappear. Reducing Cli- by equimolar replacement with glutamate caused a concentration dependent increase in the degree of rectification. However, when Cli- was replaced with more permeant anions (NO3- and Br-), rectification was not observed. These results can be explained by a single binding site model based on Eyring rate theory, indicating that rectification is a function of the concentration and the permeability of the anions in the intracellular solution.

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