Extracellular hypotonicity induces disturbance of sodium currents in rat ventricular myocytes.

Extracellular Hypotonicity Induces Disturbance of Sodium Currents

Hypotonic solution alters ion channel activity, but little attention has been paid to voltage-dependent sodium channels. The aim of this study was to investigate the effects of hypotonic solution on transient sodium currents (I NaT) and persistent sodium currents (I NaP). We also explored whether the intracellular signal transduction systems participated in the hypotonic modifications of sodium...

Omega-conotoxin blockade of calcium currents in cultured neonatal rat cardiomyocytes: different action on EGTA-modified calcium channels.

Calcium currents from neonatal rat ventricular heart muscle cells grown in primary culture were examined using the "whole-cell" voltage clamp technique. An inward current characterized by large amplitude and slow inactivation decay was induced when the extracellular Ca2+ concentration was reduced by EGTA. This current was suppressed by extracellular Na+ removal, or by calcium antagonists, and i...

Tamoxifen inhibits sodium and potassium currents in rat ventricular myocytes

Phenylephrine-induced stimulation of Na+/Ca2+ exchange in rat ventricular myocytes.

OBJECTIVE The effect of an alpha-adrenergic agonist, phenylephrine, on the Na+/Ca2+ exchange current in rat ventricular myocytes was investigated. METHODS The Na+/Ca2+ exchange current was measured at room temperature in rat ventricular myocytes as the whole-cell current induced by addition of extracellular Na+ and Ca2+, while blocking Na+ current by setting the holding potential at -30 mV, K...

FXYD1 phosphorylation in vitro and in adult rat cardiac myocytes: threonine 69 is a novel substrate for protein kinase C.

FXYD1 (phospholemman), the primary sarcolemmal kinase substrate in the heart, is a regulator of the cardiac sodium pump. We investigated phosphorylation of FXYD1 peptides by purified kinases using HPLC, mass spectrometry, and Edman sequencing, and FXYD1 phosphorylation in cultured adult rat ventricular myocytes treated with PKA and PKC agonists by phosphospecific immunoblotting. PKA phosphoryla...