Electrophysiological effects of mexiletine (Kö1173) on ovine cardiac Purkinje fibers.

To clarify the electrophysiological mechanisms of the antiarrhythmic effects of mexiletine, we examined the actions of mexiletine (0.1--30 mg/l) on action potential characteristics (phase 0 amplitude, overshoot, maximum upstroke velocity, maximum diastolic and activation voltages, duration at 50% and 90% repolarization) of cardiac Purkinje fibers using standard microelectrode techniques. In fibers stimulated at constant rate, mexiletine decreased phase 0 amplitude and Vmax and shortened the action potential.

Prevention of increased hemoglobin-oxygen affinity in open-heart operations with inosine-phosphate-pyruvate solution.

In a control group of 32 patients undergoing open-heart operation, erythrocyte 2,3-diphosphoglycerate (2,3-DPG) declined progressively during the course of perfusion from a prebypass mean of 17.00 to 11.29 mu M per gram of hemoglobin at the end of bypass.