Corticosteroid potentiation of surfactant dose response in preterm rabbits

• Published in: Journal of applied physiology (1985) Vol. 64; no. 6; p. 2366
• Main Authors: Seidner, S, Pettenazzo, A, Ikegami, M, Jobe, A
• Format: Journal Article
• Language: English
• Published: United States 01.06.1988
• Subjects: Animals; Betamethasone - pharmacology; Female; Fetus - drug effects; Fetus - physiology; Inhalation - drug effects; Lung - drug effects; Lung - embryology; Lung - physiology; Maternal-Fetal Exchange; Pregnancy; Pulmonary Surfactants - physiology; Rabbits; Reference Values; Tidal Volume
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/jappl.1988.64.6.2366

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.