Fig. 3. Concentrations of bupivacaine (left panels ) and thiopental (right panels ) in arterial (open triangles ) and coronary sinus (open squares ) blood from intravenous infusion of bupivacaine (HCl salt, 37.5 mg/3 min) or thiopental (sodium salt, 250 mg/3 min) under conditions of normal arterial pH, imposed acidemia, or alkalemia. Note time scale expansion for clarity.