Heart Rate of the Albino Rat.

Abstract

A method is described for recording the heart rate in resting, unanesthetized rats. The animal is placed in a specially constructed adjustable cage, so that it stands on copper plates which serve as pickup electrodes. The electrocardiogram is recorded on adding machine tape by the crystograph of Offner and Gerard, which shows physical activity on the same tracing. Predictable heart rates require about a month''s training, and at least a 10 min. rest before each run. Values obtained on 113 adult [male] rats, weighing 200-370 g., avg. 264 [plus or minus] 18 beats/ min. Increase in heart rate is caused by body movement, but this is mainly psychic under the conditions. Temp. changes of a few degrees also cause great alterations in heart rate.