Abstract
Naloxone (NLX), an antagonist of EO receptors, reverts hypotension during shock demonstrating the EO role in cardiovascular regulation during stressful conditions. Although high plasmatic concentrations of EO are found in the fetus and newborn, it is not known whether they play a role in arterial blood pressure (BP) and heart rate (HR) regulation in basal conditions. Therefore, we chronically catheterized 13 fetal sheep (0.8-0.9 of gestation) and 6 newborn lambs (5-12 days old) in order to study if NLX (bolus 0.5-lmg/kg + infusion 20ug/kg × min × 30min) modify the basal BP and HR in the fetus and newborn. Catheters were placed into femoral artery and vein and carotid artery. Five days after surgery we monitored BP and HR 30 minutes before and after the NLX injection. The results were (mean ± SD):
Heart rate did not change during the experiments. These results shuw that there are developmental changes in the cardiovascular response to EO in sheep. EO parthicipate in the basal tonic regulation of BP in the fetal but not in the neonatal life, suggesting a decrease in sensitivity to EO in the neonate in spite of the high plasmatic concentration of EO in the newborn period. Grant 2183-8623 DIB, Universidad de Chile.
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Espinoza, M., Riquelme, R., Germain, A. et al. ENDOGENOUS OPIOIDS(EO) ROLE IN THE REGULATION OF THE BASAL ARTERIAL PRESSURE AND HEART RATE DURING TIE PERINATAL PERIOD. Pediatr Res 22, 371 (1987). https://doi.org/10.1203/00006450-198709000-00045
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DOI: https://doi.org/10.1203/00006450-198709000-00045