EFFECT OF TRIIODOTHYRONINE AUGMENTATION ON RAT LUNG SURFACTANT PHOSPHOLIPIDS DURING SEPSIS

Surfactant functional effectiveness is dependent on phospholipid compo sitional integrity; sepsis decreases this through an undefined mechan ism. Sepsis-induced hypothyroidism is commensurate and may be related. This study examines the effect of 3,3',5-triiodo-L-thyronine (T-3) su pplementation on surfactant composition and function during sepsis. Ma le Sprague-Dawley rats underwent sham laparotomy (Sham) or cecal Ligat ion and puncture (CLP) with or without T-3 supplementation [CLP/T-3 (3 ng/h)]. After 6, 12, or 24 h, surfactant was obtained by lavage. Func tion was assessed by a pulsating bubble surfactometer and in vivo comp liance studies. Sepsis produced a decrease in surfactant phosphatidylg lycerol and phosphatidic acid, with an increase in lesser surface-acti ve lipids phosphatidylserine and phosphatidylinositol. Phosphatidylcho line content was not significantly changed. Sepsis caused an alteratio n in the fatty acid composition and an increase in saturation in most phospholipids. Hormonal replacement attenuated these changes. Lung com pliance and surfactant adsorption were reduced by sepsis and maintaine d by T-3 treatment. Thyroid hormone may have an active role in lung fu nctional preservation through maintenance of surfactant homeostasis du ring sepsis.