Cytosolic free Ca2+ level in isolated hepatocytes: the effect of insulin.

Cytosolic free Ca2+ level was estimated in rat hepatocytes using the method described by Murphy et al. (1980). For control hepatocytes, a value of 0.20 +/- 0.06 mumol/l was obtained. Insulin increased cytosolic free Ca2+ level to 0.63 +2- 0.24 mumol/l. No net fluxes of Ca2+ across the plasma membrane were observed during incubation of hepatocytes with insulin. Mitochondria were shown to be the main Ca2+ buffering system. FCCP released 77-88% of releasable calcium from the cell. Dibucaine increased cytosolic free Ca2+ level to 1.16 mumol/l.