Cardiac electric activity in Wistar rats during ventricular repolarization in aging

Abstract

АннотацияМетодами электрокардиографии и многоканального поверхностного картирования исследована электрическая активность сердца 4-, 12-и 18месячных крыс линии Вистар в период реполяризации желудочков. Показано значимое увеличение систолического артериального давления у крыс в процессе старения, приводящее в результате к структурно-функциональному ремоделированию миокарда. Это отражается в достоверных изменениях амплитудно-временных параметров электрического поля сердца крыс на поверхности тела и увеличении длительности реполяризации за счет ее конечного периода. Ключевые слова:поверхностное картирование кардиопотенциалов, старение, реполяризация, крыса AbstractThe experiments were carried out on 4-, 12-, 18month 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 instantaneous 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<0,05 using T-test for two independent values. The results are summarized as m±SE. ECG analysis in the second lead revealed a significant decrease in the heart rate, prolongation of the QTinterval in rats during aging. Prolongation of Tpeak-Tend and J-Tend intervals in 18-month rats in comparison with 12-and 4-month rats is shown. The study of the amplitude-temporal parameters of the cardiac electric field on the body surface during ventricular repolarization showed a decrease in the absolute value of the maximum and minimum amplitude and shortening the time of reaching the maximum values by extremes in 12-, 18-month rats compared with young animals. It is shown, that significant increase in the duration of repolarization in old rats is due to ventricular hypertrophy.