Аннотация:Backgroud and Aim. Thyroid hormones are important for proper development of cardiovascular system, but delayed consequences of early thyroid deficiency are purely investigated. In this study we aimed the effects of antenatal and early postnatal hypothyroidism on cardiovascular system regulation in adult rats. Methods. Dams were treated with propylthiouracil in drinking water (PTU, 5 ppm) throughout pregnancy and 2 weeks after delivery. Hemodynamic measurements were performed in male offspring aged 10-12 weeks. Blood pressure was recorded through a catheter in conscious unrestrained rats and processed beat-to-beat to estimate mean arterial pressure (MAP) and heart rate (HR) values. MAP power spectra were computed using a fast Fourier transform. Results. Total T4 and free T3 blood levels in offspring of PTU-treated dams compared to respective controls were prominently lower at 2-week age but higher at 10-week age. PTU group had lower HR level after cardiac autonomic blockade, developed smaller tachycardic response to tyramine and smaller pressor response to NO-synthase inhibitor. Along with that PTU group demonstrated the signs of increased sympathetic activity, such as moderate increase of MAP, increase of MAP spectral power in 0.25-0.6 Hz frequency band and enhanced depressor response to ganglionic blockade. Conclusions. Cardiovascular consequences of thyroid deficiency in early development may persist in adult age even if the levels of thyroid hormones are restored. Such hemodynamic changes may be co-directional with the changes during acute hypothyroidism or compensatory transformed into opposite changes.