Short-term diabetes alters K+ currents in rat ventricular myocytes.

Short-term diabetes alters K+ currents in rat ventricular myocytes.

The electrophysiological properties of single ventricular myocytes from control rats and from rats made diabetic by streptozotocin (STZ) injection (100 mg/kg body weight) have been investigated using whole-cell voltage-clamp measurements. Our major goal was to define the effects of diabetes on rate-dependent changes in action potential duration and the underlying outward K+ currents. As early a...

Tamoxifen inhibits Na+ and K+ currents in rat ventricular myocytes.

Tamoxifen is an estrogen receptor antagonist used in the treatment of breast cancer. However, tamoxifen has been shown to induce QT prolongation of the electrocardiogram, thereby potentially causing life-threatening polymorphic ventricular arrhythmias. The purpose of the present study was to elucidate the electrophysiological mechanism(s) that underlie the arrhythmogenic effects of tamoxifen. W...

4-Hydroxytamoxifen inhibits K(+) currents in mouse ventricular myocytes.

Tamoxifen is a widely used chemotherapeutic agent, which has been associated with prolongation of the QT interval. Other studies have reported that acute exposure to tamoxifen can reduce cardiac K(+) currents. However, in vivo tamoxifen is largely metabolized and most of its activity is attributable to its major metabolite, 4-hydroxytamoxifen (4OH-tamoxifen). Accordingly, in the present study, ...

Characterization of two distinct depolarization-activated K+ currents in isolated adult rat ventricular myocytes

Depolarization-activated outward K+ currents in isolated adult rat ventricular myocytes were characterized using the whole-cell variation of the patch-clamp recording technique. During brief depolarizations to potentials positive to -40 mV, Ca(2+)-independent outward K+ currents in these cells rise to a transient peak, followed by a slower decay to an apparent plateau. The analyses completed he...

Tamoxifen inhibits sodium and potassium currents in rat ventricular myocytes