Affiliation:
1. Department of Obstetrics and Gynaecology, University of Auckland, New Zealand.
Abstract
To test whether beta-adrenergic mechanisms and the sympathetic nervous system are involved in the synergistic action of thyrotropin-releasing hormone (TRH) and cortisol on lung maturation, fetal sheep (n = 32) were infused from 121 to 128 days of gestation with saline, TRH + cortisol, TRH + cortisol + beta-adrenergic blocker, or TRH + cortisol after chemical sympathectomy with 6-hydroxydopamine. TRH + cortisol increased lung distensibility and stability and alveolar concentrations of saturated phosphatidylcholine two- to threefold over control fetuses. beta-Adrenergic blockade prevented the increase in distensibility in response to TRH + cortisol. Sympathectomy did not impair the increase in distensibility and stability in response to TRH + cortisol but inhibited the increase in alveolar total phospholipids. Tissue concentrations of saturated phosphatidylcholine increased in TRH + cortisol-treated fetuses after either sympathectomy or beta-adrenergic blockade. We concluded that during lung maturation by TRH + cortisol 1) sympathetic mechanisms are requisite for surfactant release, 2) nonneurogenic beta-adrenergic mechanisms are requisite for the maturation of the mechanical properties of the lung and 3) stimulation of surfactant synthesis is independent of beta-adrenergic action and the sympathetic nervous system.
Publisher
American Physiological Society
Subject
Physiology (medical),Physiology
Cited by
13 articles.
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