[In vitro responsiveness of fenoterol in fetal and maternal hearts (author's transl)].

The responsiveness for fenoterol was studied in fetal and maternal hearts of guinea pig in vitro. Fenoterol had the same positiv chronotropic effect both on heart rate in fetal and adult atria independent of the baseline values. 2ng/ml fenoterol were sufficient to increase frequency both in fetal and maternal preparations; dose-response curves were parallel in both cases. These results indicate that cardiac beta-receptors are developed and functioning in fetal guinea pigs before birth.