4.8. TRPV1 desensitization tests

In an earlier study,6 we developed a battery of tests to assess the efficacy and extent of TRPV1 desensitization. Two of these were used in the present work: the writhing test (to assess the function of peritoneal TRPV1 channels) and the eye‐wiping test (to assess the function of corneal TRPV1 channels). All tests were performed 6‐16 days after the initial administration of RTX (or vehicle).

A rat was injected with RTX (0.1 μg kg⁻¹, i.p.) dissolved in 10% ethanol, and writhing episodes (abdominal muscle contraction associated with hindlimb extension) were counted for 10 minutes.

A drop (20 μL) of RTX (2 μg mL⁻¹) in 10% ethanol was applied to the cornea, and eye‐wiping movements were counted for 5 minutes.