Is demodulation an artifact of the recording technique?
Because the effects just described were observed in dialyzed cells, we next used the perforated-patch (PP) technique to keep the cells metabolically intact. The same drug application protocol used with the whole-cell recordings was used to ascertain whether the observed effects were caused by an artificial removal of cytoplasmic soluble components. Demodulation responses recorded with the perforated patch (n = 7) were similar to those recorded with the whole cell. The only difference with respect to the whole-cell recordings was the disappearance of kinetic slowing in the Som response. This was expected, because this characteristic, which probably requires protein phosphorylation, is abrogated when the perforated patch is used (Meriney et al., 1994). The demodulation observed with perforated patch was comparable with the one recorded with the whole-cell technique. However, the percentage inhibition of the Som Ca2+ current recorded with PP was smaller because of the disappearance of KS.
