[1] UNIV CALIF SAN FRANCISCO, DEPT ANESTHESIA, SAN FRANCISCO, CA 94143 USA
[2] UNIV CALIF SAN FRANCISCO, CARDIOVASC RES INST, SAN FRANCISCO, CA 94143 USA
[3] UNIV CALIF SAN FRANCISCO, DEPT PHYSIOL, SAN FRANCISCO, CA 94143 USA
[4] UNIV CALIF DAVIS, SCH VET MED, DEPT SURG & RADIOL SCI, DAVIS, CA USA