Figure 2.

Mechanisms of electrical tuning in low- frequency and high-frequency turtle hair cells. (A) Resonance arises from voltage-dependent Ca²⁺ channel (Ca_v) and Ca²⁺-activated K⁺ (K_Ca) channels. An increase in resonant frequency from 75Hz (left) to 300Hz (right) requires four-fold increase in channel numbers. (B) Examples of voltage ringing induced by current steps. (C) Cell-attached patch recordings from K_Ca channels in isolated hair cells tuned to 75 and 300 Hz (top); and K_Ca channels expressed in Xenopus oocytes, for α+β and α subunits (see references 20, 23). (D) Scheme for tonotopy: four K_Ca channel α subunits associated with one to four β subunits.