Comparative analysis of the impact of α1-and α2-adrenoreceptor blockade on cardiac function in rats during postnatal ontogeny.

We compared the effects of α1-and α2-adrenoreceptor blockade on cardiac function in rats aged 1, 3, 6 and 20 weeks. Administration of α1-adrenoblocker prazosin decreased heart rate in 20- and 6-week-old rats; in 3-week-old rats, this decrease was insignificant and in 1-week-old rats was absent. Blockade of α2-adrenoreceptors with yohimbine did not change heart rate in 6- and 20-week-old rats and induced bradycardia in 1- and 3-week old rats.