Representative electron microscopy images of cardiac mitochondria of each of the four groups.

(A) Control group mice were pretreated with saline and then received saline 5 min later. (B), (C), (D) Mice were pretreated saline, 0.1 mg/kg of isoprenalin or 5 mg of esmolol, respectively, and then received 46.7 mg/kg of bupivacaine 5 min later. Arrows indicate focal high-amplitude matrix swelling.