Abstract
Hypoxia leads to an increase in endogenous adenosine, a compound which markedly alters blood pressure and heart rate via adenosine receptors. We hypothesized that the persistence of a fetal class of such receptors into the postnatal period might induce altered regulation of heart rate and blood pressure. To investigate whether the cardiovascular response to adenosine and its non-metabolized analogs differs in the pre- and postnatal period, heart rate (HR), arterial blood pressure (BP), breathing movements (BM), and blood gases (BG) were measured in the 8 fetuses (120-140 days gestation), and lambs (6-40 days) following IV injection of varying doses of phenyl-isopropyl-adenosine (L-PIA), N-5′-ethylcarboximide-adenosine or cyclohexyladenosine (CHA). In the fetus all analogs induced dose-dependent bradycardia (<70% of basal HR); potency order was PIA > NECA > CHA. D-PIA, p <0.01. BP decreased ≤20%; BM were abolished. In the newborn lamb NECA induced significant tachycardia (≥125% of basal) but PIA and CHA decreased HR; potency order was NECA > PIA > CHA, p <0.01, no apnea was observed. We conclude that ovine fetal lamb and newborn cardiovascular and respiratory responses to adenosine-like compounds differ significantly.
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Toubas, P., Sheldon, R., Sparkman, D. et al. CARDIOVASCULAR RESPONSE TO ADENOSINE ANALOGS DIFFERS BETWEEN FETAL AND NEWBORN LAMBS. Pediatr Res 21 (Suppl 4), 242 (1987). https://doi.org/10.1203/00006450-198704010-00450
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DOI: https://doi.org/10.1203/00006450-198704010-00450