MEASUREMENT OF INTRACELLULAR NA-SENSITIVE FLUORESCENT DYE, SODIUM-BINDING BENZOFURAN ISOPHTHALATE, IN PORCINE ADRENAL CHROMAFFIN CELLS - USAGE OF PALYTOXIN AS A NA+ IONOPHORE( CONCENTRATION BY A NA+)

Palytoxin was found to equilibrate sodium ions (Na+) across the cell m embrane much faster than dose gramicidin, which has been frequently us ed to calibrate the intracellular Na+ concentration ([Na+]in), in cell s treated with a Na+-sensitive fluorescent dye, sodium-binding benzofu ran isophthalate (SBFI). Palytoxin was capable of equilibrating Na+ in cells treated with SBFI-acetoxymethyl ester (SBFI-AM) and in voltage- clamped cells loaded with SBFI through a patch pipette. Nicotine cause d a dose-dependent increase in [Na+]in in porcine adrenal chromaffin c ells treated with SBFI-AM and caused a simultaneous increase in [Na+]i n and inward current in the voltage-clamped cells loaded with SBFI. Pa lytoxin has an advantage of calibrating [Na+]in in a shorter time than dose gramicidin because of its powerful ionophoretic activity. (C) 19 97 Elsevier Science B.V.