Effect of weak electromagnetic field on cardiac work, concentration of thyroid hormones and blood aminotransferase level in the chick embryo

The aim of the study was to determine the effect of alternating electromagnetic field (EMF; 50 Hz frequency, 50 and 100 $\mu$ T induction) on cardiac work of the chick embryo. Eggs from the experimental groups were exposed to EMF throughout incubation. During the experiment, heart rate (ballistocardiographic method), thyroxine ($T_{4}$) and triiodothyronine ($T_{3}$) concentrations, heart weight, ventricle wall thickness, and levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were determined. The results show, for the first time, that the exposure of chick embryos to EMF augments the heart rate, especially from 17 days of incubation. The increased heart rate in the embryos exposed to EMF was associated with considerable increases in plasma $T_{4}$ and $_{3}$ concentrations, which were recorded during the final stage of embryogenesis. The significant effect of the 100- $\mu$ T field on heart weight and blood AST levels in the embryos suggests that EMF has a direct effect on the physiological function of cardiac muscle.