Uncoupling effects of local anesthetics on rat liver mitochondria.

We demonstrate in this paper that bupivacaine, a local anesthetic, can act alone as an uncoupler of rat liver mitochondria. It stimulates state 4 respiration, induces a swelling in potassium acetate (in the presence of valinomycin), and collapses the transmembrane potential. Lidocaine, another local anesthetic, requires the presence of a lipophilic anion such as TPB- to produce the same effects. TPB- can also reinforce the action of bupivacaine. These differences in action of the two local anesthetics can be explained by the difference in the liposolubility.