Fig. 2

Inhibition of capsaicin-activated TRPV1 current (I _TRPV1,Cap) by hypoxia. a Representative current trace showing response to hypoxia during activation by 200 nM capsaicin. Vertical lines reflect current responses to the repetitive ramp-like pulses from −80 to 80 mV every 10 s. Right summary of inward currents at −20 mV in response to 200 nM capsaicin (normoxia, Control), capsaicin + hypoxia [3% (n = 10) or 9% (n = 7), closed bar and hatched bar, respectively], and capsaicin + reoxygenation (Reoxy). In each cell, current amplitudes were normalized to the control current induced by 200 nM capsaicin. b An exemplary current trace at −20 mV holding voltage showing the repetitive activation of TRPV1 by 50 nM capsaicin (horizontal line). Hypoxia was applied between the second and the fourth applications of capsaicin. Note that the basal current was increased by hypoxia while the amplitude of transient inward current (I _TRPV1,Cap) was decreased. Right summary of amplitudes of I _TRPV1,Cap normalized to the first response (hatched bar) and their changes by 3% \( {\text{P}}_{{{\text{O}}_{2} }} \) (n = 5, closed bars) and 9% \( {\text{P}}_{{{\text{O}}_{2} }} \) (n = 14, open bars)