Biological variations in hemodynamics and electrocardiogram rhythms among telemetered cynomolgus monkeys

Telemetered cynomolgus monkeys are widely used in cardiovascular toxicology research. However, the biological variations in their hemodynamics and electrocardiogram rhythms have not been fully elucidated.

To determine the potential effects of sex, handling stress, and circadian rhythm on the hemodynamics and electrocardiogram rhythms, data from 23 cynomolgus monkeys, implanted with DSI telemetry devices were examined.

Our data showed that males had a longer RR interval (RRi), slower heart rate (HR), shorter QT and corrected QT intervals (QTc), and lower blood pressure than females. During the night time, the animals showed a longer RRi, PRi, QTi, and QTc; slower HR, and lower blood pressure. Handling stress at 0.25- to 1-h post-treatment caused a decrease in RRi and increase in HR and QTi. For RRi, HR, and systolic, diastolic, and mean blood pressure, the coefficients of variation (CVs) between studies of individual animals were less than 30%; for other parameters, the CVs were less than 20%.

We demonstrated that sex, circadian rhythms, and handling stress all contributed towards variations in telemetry data, albeit to different extents. For each individual animal, the biological variation across different studies was relatively small and acceptable.