1 Department of Anesthesiology and Pain Medicine, University of Toronto, Toronto, Ontario M5G 1E2, Canada; Department of Physiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada; Department of Anesthesia, Sunnybrook Health Sciences Centre, Toronto, Ontario M4N 3M5, Canada. Electronic address: beverley.orser@utoronto.ca.
2 Department of Physiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada.
3 Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario N6A 5C1, Canada.