Increased Amplitude of the Circadian Variations in Locomotor Activity, Systolic Arterial Pressure, and Heart Rate in Congenic Rats derived from SHRSP Rats

The circadian variations in the hemodynamics and locomotor activity (ACT) of congenic rats derived from stroke-prone spontaneously hypertensive (SHRSP) rats and Wistar-Kyoto (WKY) rats have not been studied in detail. We used radio telemetry and the maximum entropy method to examine these variations. The systolic arterial pressure of the congenic rats was intermediate between those of the SHRSP rats and WKY rats, while their heart rate was lower than that of the SHRSP rats. The congenic rats also showed the highest ACT. The circadian variations in the heart rates of the congenic rats were more like those of the WKY rats, and the variations in their ACT were more similar to those of the SHRSP rats.