Power density spectra of frog skin potential, current and admittance functions during patch clamp.

Clamp current fluctuations in frog skin of areas down to 0.07 cm2 are dominated by low frequency components (less than 100 Hz). Patch clamp of 0.001 cm2 under high density fluorosilicone oil exhibits components up to 5000 Hz, often including a peak in the current power density spectrum. The admittance spectrum also exhibits a peak at the same frequency. In some skins no peak was observed, but the break in the curve was too sharp to be Lorentzian. In all instances the final limiting slope approached 1/f2. The resonance peak was observed in either Cl- or SO = 4 Ringer's but disappeared when Na+ was replaced with K+. Resonance frequency varied from 100 to 700 Hz.