Brian P. Brockway

A New Method for Continuous Chronic Measurement and Recording of Blood Pressure, Heart Rate and Activity in the Rat Via Radio-telemetry

Accurate continuous chronic measurements of blood pressure from conscious laboratory rats are critical to many experimental protocols but have been difficult or impossible to acquire. A system consisting of an implantable radio-telemetry device, receiver, and computer-based data acquisition system that allows such measurements to be easily obtained has been developed. This system is capable of monitoring and recording arterial pressure (waveform, systolic, diastolic, and mean), heart rate, and activity from rats weighing greater than 175 gm for periods in excess of 6 months. Chronic patency has been achieved through a patented design which includes an antithrombogenic film and a gel membrane located at the catheter tip. Validation of telemetered measurements via carotid catheter has demonstrated the accuracy to be better than +/- 5 mmHg in 85% (N = 20) tested at 3 weeks post implantation, 86% (N = 15) tested at 8 weeks, and 78% (N = 9) at 12 weeks. Incidence of loss of patency was 2.3% (N = 44). This system has a demonstrated ability to obtain accurate continuous chronic measurements of arterial pressure free of the stressors associated with conventional systems.

Use of telemetry to record body temperature and activity in mice.

A complete, commercially available, integrated telemetry and data acquisition system is described, which is used to record core temperature and activity in mice. The system is comprised of a telemetry transmitter (implanted in the peritoneal cavity), a receiver (placed underneath the cage) connected to a computer with software (Dataquest), which converts the transmitter signals directly into core temperature and activity. The information is stored on either a floppy diskette or a hard disk in the computer. The effects of anesthesia (sodium pentobarbital, halothane), handling, aggregation, restraint, a cholinergic agonist (oxotremorine), and an anticholinesterase agent, soman (pinacolyl methylphosphonofluoridate), on core temperature and activity were examined. The telemetry system for the recording of core temperature and activity provides a more accurate assessment of the temporal effects of various drugs and is more efficient and less labor intensive than the use of a rectal temperature probe.

Telemetric monitoring of blood pressure in freely moving mice: a preliminary study

This paper describes for the first time the possibility for recording the systolic pressure (SPI, diastolic pressure (DP), and the mean arterial pressure (MAP) as well as the heart rate (HR) and locomotor activity (LA) in freely moving mice, using a commercially available telemetry and data acquisition system. The system comprises a new, small radio-telemetry transmitter implanted in the peritoneal cavity, a receiver board placed underneath the home cage, a multiplexer and a computer-based data acquisition system. The signals from the receiver were consolidated by the multiplexer and were stored and analysed by the computer. The telemetered pressure signals (absolute pressure) were corrected automatically for changes in atmospheric pressure measured by an ambient pressure monitor. The effects of implantation on animal behaviour, and, after the animals had recovered, the effects of handling on the SP, DP, MAP and HR were examined. The radio-telemetry system for recording the SP, DP, MAP and HR provides an accurate and reliable method for monitoring the direct effects of handling on SP, DP, MAP and HR. In addition, by using this new blood pressure (BP) transmitter, we maintain that BP measurements in freely moving mice are more efficient, reliable, and less labour-intensive than the measurement techniques described in the literature thus far.