Figure 3: Effects of the biguanides (1.0 mM) and hepatocyte bioenergetics. Liver specimens were collected as described in Methods and immediately placed in the O2 vial for measuring cellular respiration at 37°C in the presence and absence of 1.0 mM biguanides (Panels A-B). For ATP determination, collected liver specimens were incubated at 37°C in RPMI (gassed with 95% O2: 5% CO2) for 60 min in with and without 1.0 mM biguanides (Panel C). Panel A: Representative O2 runs (a typical experiment involving 4 mice) in the presence of 1.0 mM metformin, buformin, phenformin or no addition. The lines are linear fits. The rate of respiration (k, μM O2 min-1) was the negative of the slope of [O2] vs. t. The values of kc (μM O2 min-1 mg-1) are shown at the bottom of each run. Panel B: Summary of the values of kc (seven separate experiments involving 28 mice) with 1.0 mM metformin, buformin, phenformin or no addition. The lines are mean. Panel C: Summary of cellular ATP with 1.0 mM metformin, buformin, phenformin or no addition (seven separate experiments involving 28 mice). The lines are mean.