RECEPTOR-MEDIATED MN2- COMPARISON OF CELLS LOADED WITH FURA-2 ESTER AND CELLS MICROINJECTED WITH FURA-2 SALT( INFLUX IN RAT HEPATOCYTES )

In single Fura-2 ester-loaded hepatocytes, stimulation by vasopressin, but not emptying of the agonist-sensitive Ca2+ store by 2,5-di-(t-but yl)hydroquinone, resulted in an increase in the rate of Fura-2 fluores cence-quenching by Mn2+. Similarly, in cells microinjected with Fura-2 salt, vasopressin stimulated Mn2+ entry while 2,5-di-(t-butyl)hydroqu inone or thapsigargin did not. The pattern of Fura-2 quenching by Mn2 only correlated with the movement of Mn2+ across the plasma membrane.