Bradycardia during face cooling in man may be produced by selective brain cooling.

In human subjects, bradycardia was produced by immersing the subjects' faces in water at 15 degrees C when they were hyperthermic. When they were hypothermic, the same face cooling produced tachycardia. It is suggested that the difference in cardiac response originates in selective brain cooling during hyperthermia, by venous return from the face to the brain, via ophthalmic veins.