Fig. 1. Representative traces of the hemodynamic and electrocardiographic responses to a rapid intravenous injection of bupivacaine (2 mg/kg) in a conscious rat. Panels represent time epochs extracted from a single record and divided by thick vertical lines. Dotted lines indicate baseline values. Traces (in order from top to bottom) are mean arterial pressure, pen recorder time marks (1 per second), pulsatile arterial blood pressure, and electrocardiogram (lead 11). (A ) Predrug control. (B–E ) Segmental records from the times indicated. Bupivacaine was administered 3 s before the beginning of epoch B . Traces feature (B ) initial electrocardiogram change (3 s), (C ) early hypertensive phase (10 s), (D ) convulsion (13 s), and (E ) late phase when blood pressure returns to near baseline (1.5 min).