Figure 6.

Stimulation of proton conductance by LA in isolated mitochondria from stigma-stage thermogenic florets. Purified mitochondria were incubated with 1 mm NADH substrate in assay medium containing 1 μm oligomycin (to inhibit ATP synthase), 0.1 μm nigericin (to clamp the ΔpH), 6 μm carboxyatractyloside (to inhibit adenine nucleotide translocase), and 100 μm n-propyl gallate (to inhibit SrAOX). The kinetics of proton conductance were then examined by simultaneous measurement of respiration and membrane potential. A, LA-induced dose-dependent increase in proton conductance. Increasing concentrations of LA (0–15 μm) were obtained by successive additions when the steady-state respiration rate and membrane potential were attained. B, The effects of 5 μm LA on the kinetics of proton conductance were examined with a KCN titration. The results shown are the mean ± sd of three measurements using mitochondria from the same preparation.