1. Professor of Anesthesia, Department of Anesthesia, and Associate, Cardiovascular Research Institute, University of California, San Francisco, California 94122.
2. Research Trainee, Department of Anesthesia, University of California, San Francisco, California 94122.
3. Associate Professor of Anesthesiology, Department of Anesthesiology, University of California, Davis, California 95616. Present address: Department of Anesthesia, University of Florida, Gainesville. Florida.