Fig. 8.
Hypothetical lipid membrane pore configurations and transitions that might explain the observed variability in the duration of ultrasound (US)-induced conductance (gus). US or other forces, e.g., radio frequency (RF) electric fields, increases the probability of lateral movement in lipids and the formation of unstable hydrophobic pores (1), and from there to wider transition pores (2). These unstable transition pores would in turn have a high transition rate (heavy arrow) toward formation of semistable hydrophilic pores (3) that could mediate long-lasting gus activation. Rapid gus closing could result from high transition rates from 2 to 1, and 1 to 0, whereas transition from the semistable state 3 to 1 would be impeded by the higher energy of the transition pore state (2). Inset: hypothesized membrane energy levels for each state and US- or RF-facilitated transitions (lipid channels 1 and 3 inspired by Fig. 1 of Böckmann et al. 2008 and Fig. 4 of Krasovitski et al. 2011).