Figure 6. Increases in [Ca²⁺]_i caused by PKC activation and capsaicin.

A, PMA application (10 μm) caused no change in [Ca²⁺]_i in the majority of capsaicin-sensitive rat DRG neurones. Capsaicin concentration, 10 μm. B, in 6 out of 174 capsaicin-responsive DRG neurones a small increase in [Ca²⁺]_i was observed (largest example shown here). Mean amplitude (F/F_max) was 0.12 ± 0.3. In similar experiments on DRG neurones from adult mice 2 out of 52 capsaicin-sensitive neurones responded to 1 μm PMA with an increase in [Ca²⁺]_i. C, no significant increase in [Ca²⁺]_i was seen in response to 10 μm PMA in HEK293 cells stably transfected with the hVR1 gene (10 coverslips, 216 cells). Capsaicin concentration was 1 μm. Untransfected HEK293 cells also did not respond to PMA (5 coverslips, 285 cells).