Phosphatidylinositol-4,5-Biphosphate (PI(4,5)P₂) Is Required for Rapid Endocytosis in Chromaffin Cells

Table 1

Statistical analysis of rapid endocytosis parameters in chromaffin cells.

Treatment	Cm increase (fF)	RE duration (sec)	Peak current (pA)	Cumulative current integral (pC)
Control ()
PAO ()		—
AbPI4K ()		—
PI(4,5)P2 ()
PAO + PI(4,5)P2; (n =19)
AbPI4K + PI(4,5)P2 ()
PAO + DTT ()

Whole-cell membrane capacitance (Cm) records of exocytosis and rapid endocytosis (RE) were acquired and analyzed according to our previously described methods [7, 8]. Total Cm increase and total Cm decrease correspond respectively to the maximum increase and the maximum decrease of Cm induced by voltage depolarization (see Materials & Methods). The duration of RE is the time required for Cm to return to baseline from the maximum level after stimulation (, , significantly different from control). Peak current corresponds to the maximum Ca²⁺ current amplitude evoked by the first pulse in the train of stimulation. Cumulative current integral is calculated from the total number of Ca²⁺ ions entering the cell during the entire stimulation period (10 depolarizations of 50 ms).