**1. Introduction**

144 Modern Telemetry

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Measurement of physiological parameters in laboratory animals plays an important role in evaluating the biomedical applications. It has been widely known that a telemetry system is useful for these studies, because the telemetry system can obtain physiological measurements from conscious and unrestrained laboratory animals. Maurey was the first to report on a telemetry experiment in the scientific literature (see Mackay, 1970). Mackay wrote the experiment as follows: *"A rubber bulb detects the shortening of the pectoral muscle of a pigeon by its thickening the pneumatic signal traveling a rubber tube to a bulb pushing a stylus on a smoked arum. A flapping vane at the wingtip opens and closes an electric contact to indicate the relative duration of the period of elevation and depression of the wing."* One of the first telemetry experiments with the use of a radio signal is reported by Barr (1954). From the late 1950's, several research groups have developed radio-telemetry devices for laboratory animals (Gold & Malcolm, 1957; Essler & Folk, 1961; Franklin, et al., 1964). Although telemetry technology for monitoring laboratory animals have already existed since the early 1950's as described above, fully implantable and reliable telemetry devices for monitoring physiological functions in laboratory animals have been made commercially available since the late 1980's. Advances and further miniaturization of the implantable devices in the beginning of 1990's have provided to measure electrocardiogram (ECG), electromyogram (EMG), electroencephalogram (EEG), blood pressure (BP), body temperature (BT), and locomotor activity (LA). Therefore, the number of publications in which radio-telemetric results in laboratory animals has been tremendously increased for 2 decade. In these days, many companies commercially supply the radio-telemetry implants for monitoring physiological parameters.

In this report, I would like to introduce a newly developed telemetry system in Japanese company and some useful software to analyze ECG data in the fields of cardiology and pathophysiology as well as pharmacology and toxicology. Further, I describe some experimental studies using a telemetry system and applications.

#### **2. Newly developed telemetry system**

The telemetry system for rat and mouse consists of an implantable transmitter (ATE-01S) with a pair of flexible leads, a telemetry receiver (ATR-1001) and connected acquisition system (Softron ECG Processor; EP95) to personal computer (Fig. 1).

Recent Advances in Telemetry Monitoring and Analysis for Laboratory Animals 147

SP2000 consists of the acquisition program and basic analyzing program for ECGs. The acquisition program can collect the data for a specific length of time or continuously and save it on the computer's hard drive. The acquisition program consists of a Config, WaveIn,

The Config (Configulation module) allows users to create a file that contains settings for detecting and collecting data signals during a study and to modify an existing configuration file for use in a different study. To record ECG waves, WaveIn is opened after setting of configulaton. The analyzing program calculates the points and characteristic values of an

Fig. 2. Picture of a transmitter implantation in rat.

Fig. 3. Main menu (left) and WaveIn screen (right) of SP2000.

Replay, Edit, Print etc as shown in Fig. 3.

**4.1 SP2000** 

Fig. 1. Picture and schematic drawing of a newly developed telemetry system for recording ECGs. A telemetry transmitter is on a telemetry receiver.

The implantable transmitter consists of a hermetically sealed plastic housing with a biocompatible silastic coating, occupying a volume of less than 1.9 ml and weighing approximately 3.8 g. Each transmitter contains an amplifier, a battery, radio-frequency electronics, a pair of flexible leads with 20 cm and a magnetically activated switch which allows the device to be turned on and off either *in vivo* or *ex vivo*. The transmitter passes the ECG signal to a receiver located beneath the animal cage via radio signal. The data acquisition system records and stores the raw telemetered data into the hard disk for subsequent analysis as described below (Section 4).
