Fig. 5.  Fatty acid transport into the mitochondrial matrix. The acyl group of long-chain acyl-coenzyme A (CoA), the active form of long-chain fatty acids, is transferred to carnitine via  carnitine palmitoyltransferase I (CPT I), forming acylcarnitine and generating free coenzyme A. Acylcarnitine is transported into the mitochondrial matrix via  carnitine-acylcarnitine translocase (CACT). Carnitine palmitoyltransferase II (CPT II) regenerates free carnitine by catalyzing the transfer of the acyl group from carnitine to coenzyme A in the mitochondrial matrix. Carnitine is transported back to the cytoplasm via  carnitine-acylcarnitine translocase as free carnitine or acetyl carnitine after acetylation via  carnitine acetyl transferase (CAT). Bupivacaine strongly inhibits carnitine-acylcarnitine translocase, thereby preventing the entry of long-chain acylcarnitine into the mitochondrial matrix and reducing the return of carnitine into the cytoplasm.