The respiratory responses to theophylline during normoxia and hypoxia were determined in 13 un-anesthetized fetal sheep. Theophylline (plasma levels ~ 111 μmol/L) increased the incidence of fetal breathing movements measured over 120 min from 37.7 ± 4.8% to 61.1 ± 5.7% (SEM) in normoxic fetuses. In isocapnic hypoxia (arterial O2 tension ~1.86 kPa), theophylline increased the incidence from 20.0 ± 6.3 to 52.0 ± 6.1%. Theophylline also resulted in an increase in the slope of inspiration during both normoxia and hypoxia. We conclude that adenosine modulates fetal respiratory drive during normoxia and hypoxia.
ASJC Scopus subject areas
- Pediatrics, Perinatology, and Child Health