Effects of low concentration of dihydroouabain on intracellular calcium in guinea pig ventricular myocytes / 生理学报

ABSTRACT

The effects of low concentration of dihydroouabain (DHO) on intracellular calcium concentration ([Ca(2+)](i)) were investigated in guinea pig ventricular myocytes. [Ca(2+)](i) was detected by confocal microscopy and represented by fluorescent intensity. DHO (1 fmol/L~1 mmol/L) increased [Ca(2+)](i), especially at 10 pmol/L. Nisoldipine, egtazic acid, or tetrodotoxin partially inhibited the effect of 10 pmol/L DHO on [Ca(2+)](i). The effects of DHO remained in the absence of extracellular K(+) and Na(+). These results suggest that low concentration of DHO might increase [Ca(2+)](i) via the receptor-operated Ca(2+) channels, TTX-sensitive Na(+) channels or/and triggering of intracellular calcium release; Na(+)/K(+) pump and Na(+)/Ca(2+) exchange seem not involved in the effect of DHO.