Fig. 9.

Intracellular dialysis with S100A1, via patch pipette, enhances whole cell Ca²⁺ currents. A and B: representative superimposed Ca²⁺ channel current traces, with Ba²⁺ as charge carrier (I_Ba) (1 mM), from a neuron dialyzed with the control internal solution (A) and from another neuron dialyzed with internal solution containing 10 μM S100A1 (B). A total of 20 current traces were elicited with the voltage-clamp protocol illustrated at top and delivered every 10 s. Next to the current traces are expanded time views of the outlined region of current at the end of the test pulse. The first and last traces are shown as dark lines. In control neurons step and tail current amplitudes of the first and last current traces are similar (A); however, in S100A1-dialyzed neurons there is marked difference in amplitude between the first and last traces (dark lines, B). C: time course of the action of intracellular dialysis of S100A1 on peak Ca²⁺ channel current. Peak current amplitude (I_Ba) was normalized to the current amplitude obtained at the start of acquisition (I_Ba at 0 s). Con, control neurons (n = 8); S100A1, S100A1-dialyzed neurons (n = 12). D: transmitted light (a, c) and confocal (b, d) images of a 24-h cultured SCG neuron before (a, b) and 3 min after (c, d) breakthrough into the whole cell configuration and dialysis with S100A1-Alexa 488. Continuous green lines in b and d show fluorescence profile intensities of images taken at the position indicated by dashed lines. Vertical scale bar, fluorescence intensity (500 arbitrary units); horizontal scale bar, 10 μm.