Fig. 1. Time course of changes in arterial blood pH and gases in studies with intravenous infusion of bupivacaine (HCl salt, 37.5 mg/3 min) or thiopental (sodium salt, 250 mg/3 min) with normal arterial pH (closed diamonds ), imposed acidemia (closed circles ) or alkalemia (closed squares ); acidemia (open circles ) or alkalemia (open squares ) without drug are also shown. Time 0 denotes commencement of drug or saline infusion. Note time scale expansion for clarity.