Fig. 7. THP inhibits TRPM2 calcium influx in vitro and TRPM2 inhibition in vivo reduces oxidative damage.

(A-D) HEK293 cells expressing a tetracycline-inducible TRPM2 channel were treated with doxycycline or vehicle control (vehicle control, no TRPM2) for 24 hours before loading with the calcium indicator Fluo-4. Cells were pre-treated with THP, human serum albumin (HSA) or N-(p-amylcinnamoyl) anthranilic acid (ACA), respectively, prior to activation of the TRPM2 channel with H₂O₂. Calcium influx was measured following addition of extracellular calcium (CaCl₂). In (A) pre-treatment with 1 μg/ml THP is shown. In (B) pre-treatment with 1 μg/ml THP is compared to 1 μg/ml HSA. In (C), pre-treatment with 0.01 μg/ml, 0.1 μg/ml and 1 μg/ml THP are compared. In (D), treatment with 1 μg/ml THP is compared to 25 μM ACA, a small molecule inhibitor of TRPM2. Representative results are shown from a single experiment (n=3 wells per treatment condition).

(E) Concentration of oxidative DNA damage (8OHdG) in THP^−/− mice treated with the TRPM2 inhibitor 2-aminoethyoxydiphenyl borate (2-APB, 16 mg/kg) or vehicle (10% DMSO/90% sterile saline) for three days (n=7–8 mice/group).

(F) Concentration of oxidative DNA damage (8OHdG) in THP^−/− and THP^+/+ mice treated with TRPM2 inhibitor 2-APB (16 mg/kg) or vehicle (10% DMSO/90% sterile saline) for three days before performing a 22-minute bilateral clamping of the renal artery followed by six hour recovery. (n=7–8 mice/group).

Scatter plots are mean ± standard deviation. * denotes statistical significance (p<0.05). **** denotes statistical significance (p<0.0001)