Abstract
In sheep, FBM occur intermittently, and only during low voltage, fast electrocortical activity; at birth, when PGE2 concentrations ([PGE2]) fall, breathing becomes continuous. Meclofenamate (Mec), a PG synthetase inhibitor, decreases [PGE2] and stimulates FBM to occur almost continuously, even during high voltage, slow electrocortical activity (HVSA). To investigate the role of PGE2 in regulating FBM, we studied 6 fetal sheep at 127-134d gestation. We infused Mec for 34 hr; after 12 hr we added incremental doses of PGE2, each for 2-3 hr. These caused no changes in pH, Pco2, Po2, or blood pressure. Mec decreased [PGE2] to neonatal levels and increased the incidence of FBM, especially during HVSA. Effects of PGE2 on FBM during Mec are:
The relationship between PGE2 dose and FBM can be described by a curvilinear equation (r =0.77, p <0.001). At a dose of 36 ng/kg/ min, PGE2 closely reproduced the pattern of FBM seen during control periods. These data support the hypotheses: a) endogenous PGE2 inhibits FBM during HVSA, and b) at birth, the fall in circulating [PGE2] contributes to the onset of continuous breathing. (Supported by USPHS HL 27356 Pulmonary SCOR and ALA Fellowship Grant.)
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Wallen, L., Clyman, R., Murai, D. et al. REGULATION OF FETAL BREATHING MOVEMENTS (FBM) IN SHEEP BY PROSTAGLANDIN (PG) E2. Pediatr Res 18 (Suppl 4), 354 (1984). https://doi.org/10.1203/00006450-198404001-01566
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DOI: https://doi.org/10.1203/00006450-198404001-01566