Abstract: AIM To explore whether chloride channel currents are present when apoptotic volume decrease (AVD) happens during the early times of neonatal rat cardiomyocytes apoptosis induced by staurosporine (STS), and to study the electrophysiological properties of chloride channel currents. METHODS Primary cultured neonatal rat cardiomyocytes were subjected to hypotonic and isotonic perfusion containing 4 μmol/L STS, respectively. We used whole-cell patch-clamp techniques to record chloride channel currents.RESULTS ①After exposure of cardiac myocytes to hypotonic solution, we recorded chloride channel currents which resembled volume-sensitive chloride channel currents (ICl,Vol): outward rectification, time dependent inactivation, sensitivity to 4,4′-diisothiocya-natostilbene-2,2′-disulfonicacid (DIDS). ②After exposure of cardiac myocytes to 4 μmol/L STS isotonic solution, chloride channel currents showing characterizations of ICl,Vol were also recorded. The currents were voltage dependently blocked by 500μmol/L DIDS at +40mV,+60mV,+80mV,+100mV. CONCLUSION It’s the first time to record similar volume-sensitive outwardly rectifying Cl-currents by STS in primary cultured neonatal rat cardiomyocytes.