**3. Transmitter implantation**

In many studies, the typical implantation procedure for monitoring ECG is positioning the body of the transmitter in the peritoneal cavity of the laboratory animals. However, we usually implant a telemetry transmitter for ECG chronically into the notal subcutanea under pentobarbital sodium anesthesia (40 mg/kg, intraperitoneally), because this procedure can easily perform and much less invasive and/or damaged for laboratory animals than in the peritoneal cavity procedure. Before making the incision in the skin of the animal, we use a clipper to remove the hair from the operation area of the anesthetized animal. The animal is placed on a hot plate to avoid hypothermia during procedure, and the operation area is sterilized with iodine. A 1.0-1.5 cm long incision in the skin is made, and transmitter is implanted into the subcutaneous area as shown in Fig. 2. Both electrodes are situated in the direction of the head of the animal. Paired electrodes of the transmitter are placed under the skin of the dorsal and ventral thorax to record the apex-base (A-B) lead ECG. When both electrodes are fixed on their places, the transmitter is activated by a magnet close to the transmitter body. When the battery of the transmitter is switched on, the heart beats are clearly audible within a few seconds. To complete the operation, the incision of skin is closed with absorbable suture or Michel clips.
