In some instances electrical access to the cytosolic compartment is required in a manner that prevents
wash-out of second messengers. This is typically achieved with ionophores, like nystatin or amphotericin, and provides access for small ions only. The disadvantages of this approach compared to traditional whole cell preparations
are the larger access resistance and the lack of chemical control over the intracellular compartment. For example,
with perforated patches, the application of K⁺ channel blocking ions for measuring Ca²⁺ channels is not feasible.

When using Flyscreen^® , amphotericin produces perforated patch access within 200 ms. Access resistance ranges
from 5-12 MOhm, and seal stability is unaltered when compared to whole cell preparations. The figure shows an example for a recording obtained with perforated patch.

The voltage gated K⁺ channel Kv1.3 in standard saline followed by a recording in symmetrical K⁺ in a Jurkat T lymphocyte perforated with amphotericin.