The effects of nanomolar concentration of dihydroouabain (DHO) on L-type calcium current (I Ca-L), TTX-sensitive calcium current (I Ca(TTX)), and intracellular calcium concentration ([Ca 2+] i) were investigated in guinea pig ventricular myocytes. The whole-cell patch-clamp technique was used to record I Ca-L and I Ca(TTX); [Ca 2+] i was detected and recorded with the confocal microscopy. The nanomolar concentration of DHO increased the I Ca-L, I Ca(TTX), and [Ca 2+] i, which could be partially inhibited by nisoldipine or TTX, but still appeared in the absence of extracellular K + and Na +. These data suggest that DHO could increase [Ca 2+] i in non-beating myocytes via stimulating the I Ca-L and I Ca(TTX), or perhaps triggering directly a release of intracellular calcium.