Hypotension in the chronically hypoxic chicken embryo is related to the β-adrenergic response of chorioallantoic and femoral arteries and not to bradycardia
2011 (English)In: American Journal of Physiology. Regulatory Integrative and Comparative Physiology, ISSN 0363-6119, E-ISSN 1522-1490, Vol. 301, no 4, R1161-R1168 p.Article in journal (Refereed) Published
Prolonged fetal hypoxia leads to growth restriction and can cause detrimental pre- and postnatal alterations. The embryonic chicken is a valuable model to study such effects of prenatal hypoxia, but little is known about long-term hypoxic effects on cardiovascular regulation in the chicken embryo. We investigated heart rate and blood pressure responses to chronic prenatal hypoxia in the chicken embryo (19 days) and hypothesized that it would exhibit hypotension due to bradycardia and βAR-mediated relaxation of the systemic (femoral) and/or the chorioallantoic (CA) arteries. We first measured heart rate (HR) and blood pressure (BP) in 19 day embryos incubated from day 0 in normoxia or hypoxia (14-15% O2). Secondly, we studied β-adrenoceptor (βAR)-mediated contraction, relaxation to the β-adrenoceptor (βAR) agonist isoproterenol and relaxation to forskolin in femoral and CA arteries using wire myography techniques. Chronic hypoxia caused a close to significant hypotension compared to the controls (Mean arterial pressure 3.19±0.18 vs. 2.59±0.13 kPa, normoxia vs. hypoxia respectively, P=0.056), but not bradycardia. All vessels relaxed in response to βAR stimulation with isoproterenol, but the CAM arteries completely lacked an βAR response. Furthermore, hypoxia increased the sensitivity of femoral (but not CA arteries) to isoproterenol. Hypoxia also increased the responsiveness of femoral arteries to the adenylate cyclase activator forskolin. In conclusion, hypotension in chronically hypoxic chicken embryos is more likely the consequence of elevated levels of circulating catecholamines acting on vascular beds with exclusive (CA arteries) or exacerbated (femoral arteries) βAR-mediated relaxation, rather than a consequence of bradycardia.
Place, publisher, year, edition, pages
American Physiological Society , 2011. Vol. 301, no 4, R1161-R1168 p.
Prenatal hypoxia, hypoxic hypotension, chorioallantoic membrane, β-adrenoceptors, α-adrenoceptors
IdentifiersURN: urn:nbn:se:liu:diva-65359DOI: 10.1152/ajpregu.00458.2010ISI: 000295881600031OAI: oai:DiVA.org:liu-65359DiVA: diva2:395191
Funding agencies|FORMAS, the Swedish Research Council for Environment||Agricultural Sciences and Spatial Planning||Wallenberg Foundation||2011-02-042011-02-042011-11-04