Method for measurement of heart rate in awake, noninstrumented small mammals

A method is described that enables the researcher to determine the heart rate in awake, noninstrumented small animals by recording the electrocardiogram (ECG) via the paws. Single animals are placed in a cage that has metal plates built into its floor. Through switches any two plates can be connected with an ECG recorder whenever contact with at least one front and one hind paw is made. The heart rate is then determined by measuring the number of R waves per unit of time. In rats of 140 and 300 g body wt mean resting heart rates of 384 +/- 10 and 320 +/- 4 beats/min, respectively, have been measured with this method.