Abstract
The telemetric measurement of cardiovascular and respiratory parameters in conscious, freely moving animals is an essential component of safety pharmacology studies. It is well known that heart rates as well as blood pressure values are different when measured in freely moving animals compared to restrained and/or in anaesthetized animals. For these reasons, data obtained by telemetry are considered to reflect the physiological condition. It was the aim of this study to evaluate an ITS system for the measurement of aortic blood pressure, ECG waveforms, temperature and intra-thoracic-pressure (ITP). Overall, six mature male cynomolgus monkeys (> 6.0 kg) were implanted with telemetry devices. Two male animals were dosed on two successive days with sotalol, ketamine, theophylline and chlorpromazine, respectively with saline as the corresponding vehicle. Biopotential signals were measured two hours before dosing and for a 6 hour period thereafter. Ketamine at 20 mg/kg caused a marked decrease in body temperature and in maximum ITP. QT-interval was markedly prolonged, heart rates and mean-arterial-blood-pressure were decreased at 10 mg/kg sotalol. Respiratory rate was decreased whereas the minimum ITP was slightly elevated following 25 mg/kg chlorpromazine administration. Theophylline at 20 mg/kg elicited no effect. On repeated occasions, pair- and single-housing of the two animals were compared: Heart rates as well as respiratory rates were reproducibly lower during pair-housing compared to single housing, whereas blood pressure remained unaltered. In conclusion, the ITS system is a valid tool for the selective detection of drug induced changes for cardiovascular/ respiratory parameters in conscious, freely moving monkeys. The ITS approach appears also feasible for animals under group housing conditions.
