Acute blockade of β 1 ‐receptors in the asphyxiated sheep fetus

• Published in: Acta Physiologica Scandinavica
• Main Authors: DAGBJARTSSON, A., KJELLMER, I., ROSÉN, K. G.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1987
• Subjects: Physiology; Iceland
• Online Access: http://dx.doi.org/10.1111/j.1748-1716.1987.tb08152.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1748-1716.1987.tb08152.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1748-1716.1987.tb08152.x

Acute blockade of β 1 ‐receptors in the asphyxiated sheep fetus. Acta Physiol Scand 130 , 381–385. Received 5 November 1986, accepted 9 February 1987. ISSN 0001–6772. Department of Paediatrics, Landspitalinn, University Hospital, Reykjavik, Iceland and Department of Physiology and Department of Paediatrics I, University of Goteborg, Sweden. The effects of acute β 1 ‐blockade on fetal cardiovascular reactions during asphyxia were evaluated in 11 exteriorized sheep fetuses. Gestational age was 110–142 days. Asphyxia was induced either by ventilating the mother with low oxygen gas mixture or by mechanical reduction of placental blood flow. During asphyxia all fetuses reacted to metoprolol injection with a decrease in heart rate, myocardial contractility, cardiac output and arterial blood pressure. Five experiments resulted in irreversible fetal cardiovascular collapse. Isoprenaline was given to the fetuses during hypoxia to test the ability to further increase heart rate and activate myocardial β‐adrenoceptors. In those experiments with fetal cardiovascular demise after metoprolol, the isoprenaline injection did not result in a significant tachycardia. The surviving fetuses could increase their heart rate as a sign of a capacity to further increase the sympatho‐adrenergic drive.