Age-related changes in rhythmic electrical activity in the cervical sympathetic trunk in rats and cats.

Baseline electrical activity in the cervical sympathetic trunk was studied in neonatal rats and cats and at ages 10, 20, and 30 days and two and six months, using spectral analysis. Rats from the neonatal period to the end of the first month of life and cats to 20 days of life showed increases at the amplitudes of electrical oscillations. From birth, all animals showed oscillations in the respiratory and cardiac rhythms. From day 20, frequencies with a cardiac component in rats dominated the power spectrum. The proportion of other frequencies, not associated with the cardiac or respiratory rhythms, was smaller. In cats, unlike the situation in rats, there were no age-related changes in the spectral composition of baseline electrical activity. High-frequency oscillations were recorded in cats from birth.