Cardiac electric activity in Wistar rats during ventricular repolarization in anging

The experiments were carried out on 4-, 12-, 18- month Wistar rats narcotized with zoletil (35 mg/kg intramuscularly). Unipolar body surface potentials (BSPs) were recorded by a synchronous multichannel system using 64 electrodes placed evenly around the rat's chest. Simultaneously, the bipolar ECG from the extremities was recorded. Heart rate, duration of the QT and T-wave intervals: J-Tpeak (from the J point to T-wave peak), Tpeak-Tend (from the T-wave peak to its end) and J-Tend (from the J point to the end of the T-wave) were measured on the ECG in the second lead from the extremities. The analysis of the cardiac electric field was carried out using isopotential instantane- ous maps recorded during ventricular repolarization. The time (msec) was counted relative to R peak of the ECG recorded in the second standard lead. The data were analyzed statistically at p