The Electrocardiogram as an Indicator of Acceleration Stress

By means of a transistor amplifier mounted before the slip rings of an animal centrifuge it was possible to obtain recordings of the EKG of rats under acceleration stress. With this information, a physiological end point for the tolerance of the rat to 20 G (positive acceleration) was defined as the time to reduce the heart rate of the animal from an initial state ranging from seven to nine beats per second to a final moribund state of 2 beats per second. The instrumentation and techniques employed permit the option of recovering the animal alive after approaching the limit of tolerance to acceleration.