Table 1

Statistical analysis of the molecular requirements for SE versus RE in chromaffin cells

ConditionsPeak current, pACumulative current integral, pCTotal Cm increase, fFRate of endocytosis, fF/minEndocytosis duration, min
SE
 120 mM K+ (n = 46)684  ± 25807  ± 181,888  ± 123138  ± 910.1  ± 0.33
 0 mM K+ (n = 24)686  ± 22794  ± 281,945  ± 166
 Anticlathrin IgG (n = 18)690  ± 24809  ± 331,911  ± 190
 Antidynamin-1 IgG (n = 21)700  ± 37808  ± 282,024  ± 169140  ± 1010.5  ± 0.43
 Antidynamin-2 IgG (n = 18)701  ± 29802  ± 401,790  ± 128
 Strontium (n = 16)761  ± 341,047  ± 631,877  ± 21098  ± 13.515  ± 1
 Perforated patch (n = 18)680  ± 32787  ± 402,010  ± 142150  ± 1211  ± 0.7
RE
 120 mM K+ (n = 89)741  ± 24190.2  ± 4.5605  ± 34.76,055  ± 137.20.328  ± 0.013
 Antidynamin-1 IgG (n = 73)683  ± 22189.8  ± 4.9717  ± 40.7
 Antidynamin-2 IgG (n = 30)740  ± 39194.2  ± 7.5613  ± 49.35,771  ± 143.80.313  ± 0.024
 Perforated patch (n = 34)699  ± 38188.7  ± 6.9608  ± 52.16,009  ± 1890.314  ± 0.019
  • Explanation of measurements: 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 for RE and 29 of 75 ms for SE). Total Cm increase is the maximum increase of membrane capacitance at the end of the train of stimulation. Rate of endocytosis for SE was obtained by measuring the slope of the declining Cm trace. Rate of endocytosis for RE was obtained by measuring the steepest downward slope of Cm trace. The endocytosis duration is the time required for Cm to return to baseline from its maximum level after stimulation. Perforated patch values (120 mM K+) were not significantly different from whole-cell controls. Measurements are given as means ± SEM. Dashes indicate not significantly different from zero.