Fig. 2. Effects of bupivacaine enantiomers on mitochondrial adenosine triphosphate (ATP) synthesis during adenosine diphosphate (ADP)-stimulated respiration with pyruvate as substrate. ATP produced was measured by bioluminescence after addition of 1 mm ADP in the oxygraph cuvette. ATP synthesis rate in the presence of local anesthetics is given as the percent of the ATP production in the absence of local anesthetics. Data are presented as mean ± SD (n = 5). From curve fitting: for R  (+)-bupivacaine, IC⁵⁰ = 2.2 ± 0.4 mm, n = 1.7 (r²= 0.9884); for S  (−)-bupivacaine, IC⁵⁰ = 2.5 ± 0.2 mm, n = 2.1 (r²= 0.9976).