Corticosteroid potentiation of surfactant dose response in preterm rabbits.
Fetal rabbits were treated with corticosteroids by maternal administration for 48 h before delivery at 27 days gestational age. Both corticosteroid-treated and control animals then received exogenous natural rabbit surfactant at birth at doses of 0-75 mg lipid/kg. After 10 min of ventilation at tidal volumes of 12-15 ml/kg, static pressure-volume measurements were made. At all surfactant doses there was a significantly higher maximal lung volume, higher dynamic compliance, and lower pressure requirement in the corticosteroid-treated than in the control rabbits (P less than 0.01). Control animals showed incremental improvements in dynamic compliances and maximal lung volumes up to a dose of 50 mg/kg, whereas corticosteroid treated animals improved to a maximum at the low dose of 15 mg/kg (P less than 0.01). However, surface tension as assessed by lung stability index improved with increasing surfactant dose but was not significantly different between corticosteroid-treated and control animals at a given dose. The results imply that maternal corticosteroid treatment potentiates surfactant replacement by a change in lung structure that is independent of surface tension effects.
Seidner
S
S
Department of Pediatrics, Harbor-UCLA Medical Center, Torrance 90509.
Pettenazzo
A
A
Ikegami
M
M
Jobe
A
A
D000818:Animals; D001623:Betamethasone / Q000494:pharmacology*; D005260:Female; D005333:Fetus / Q000187:drug effects / Q000502:physiology; D001239:Inhalation / Q000187:drug effects; D008168:Lung / Q000187:drug effects / Q000196:embryology* / Q000502:physiology; D008431:Maternal-Fetal Exchange; D011247:Pregnancy; D011663:Pulmonary Surfactants / Q000502:physiology*; D011817:Rabbits; D012016:Reference Values; D013990:Tidal Volume
D011663:Pulmonary Surfactants; D001623:Betamethasone