Integrative physiology
There are dedicated facilities within QMRI including zebrafish, fruit flies and metabolic studies & radiotelemetry in rodents
Animal integrative physiology
Radiotelemetry
The following is a summary of the radiotelemetry system used within the CVS. Please contact the CVS for further details or to discuss prospective projects.
What is telemetry?
A system for monitoring and collecting data from conscious, unrestrained lab animals. A miniature electronic device can relay one or more parameters. This is done via a digitised radio signal from implant to nearby receiver. The parameters include BP, HR, Activity, Temperature and ECG, whether measured directly or calculated from other parameters. Each animal requires its own transmitter and receiver, of which there are many types to accommodate a range of species. Data Sciences International have even successfully telemetered a goldfish!
Why telemetry?
It has been demonstrated that stress induced by handling and restraint, can increase plasma levels of Epinephrine and Norepinephrine 50 fold over resting values. Measurements are also free from the effects of sedation or anaesthesia. The aim is to try and eliminate any external influences not relevant to the study, which have the potential to instigate a physiological response from the subject.
What’s involved?
A telemetry system comprises of the following. The implanted devices within the animals, which sense, measure, digitise then transmit the desired parameters. The dedicated receiver pads for each animal, which detect the transmitted signal and convert it in to a computer friendly form. (Activity count is based upon the changes in signal strength detected by the receiver). The data exchange matrix multiplexes the signals from multiple receivers and relays these to the PC. The ambient pressure reference device, which is required to adjust for any changes in atmospheric pressure over the acquisition period. Finally, the Dataquest ART (Advanced Research Technology) program on the recording PC. Once a study has been approved, the animals will be sourced and given any relevant health screening/quarantine period. Once cleared and acclimatised to single housing, surgery can commence. It is advisable to order more animals than the desired ‘n’ number, as survival is generally not 100%. Depending on the ‘n’ number, surgery will be completed within 1-2weeks, and after the recovery period (1 week) is cleared, data can start to be assessed.. Acquisition can be staggered so that the first implanted animals can be recording, while the surgery continues. Average battery life for a mouse would be approximately one and a half months of continuous use.
What kind of acquisition/results?
The information acquired by the PC can be displayed in two basic formats. A continuous waveform which is really just for reference, or a list of values made from every sampling period of the subject. The sampling data can be turned in to waveform traces within DQ ART, but these are best left in this form as produced by the program. The sampling values can be converted in to Excel files and stored to ZIP disc/CD-R/Memory Stick for removal and further statistical analysis. To give some idea of sampling capabilities, a 10 second recording could be taken per animal for a group of 16 animals, every minute for more than a month. However, this produces a phenomenal volume of data to be analysed! A typical sampling protocol would be 5secs per animal per hour.
Considerations
Animal mortality is always an issue to consider, whether during or after surgery. Causes include anaesthetic death, surgery complications, post-surgery recovery and implant catheter integrity (wandering/loss of BP signal). Impedance due to subcutaneous implant placement in the mouse is a small concern, and hind limb paralysis in the Rat is a risk if occlusion of the abdominal aorta occurs for too long during surgery. The animals must also be handled with extreme care after surgery to avoid dislodging the cannula from the vessel – especially important in the mouse with the carotid cannulation.
Clinical integrative physiology
In the Wellcome Trust Clinical Research Facility, with expertise in detailed cardiovascular and metabolic investigation
