Glycogen content is affected differently in acute pulmonary and extra-pulmonary lung injury

Abstract

Acute respiratory distress syndrome (ARDS) is the most severe form of acute lung injury (ALI). The aim of the present study was to investigate whether paraquat-induced acute pulmonary and extra-pulmonary lung injury (ALI-P and ALI-EX, respectively), in rats, affects glycogen content in different tissues. This measurement could indicate performance limitations of tissues, a new biochemical aspect of ARDS. ALI-P and ALI-EX were induced by injection into the trachea (0.5 mg/kg) and intraperitoneally (20 mg/kg) 24 hours prior to tissue collection. The control groups (CTRL) received the same volume of saline. Glycogen content (mg/g tissue) from different tissues was measured using the anthrone reagent. Glycogen content in the heart and kidney was higher in the ALI-EX group than the CTRL-EX group. Glycogen content in the gastrocnemius muscle was lower in the ALI-EX group than the CTRL-EX group. However, there were no significant differences in glycogen content in the diaphragm in the ALI-EX and ALI-P groups or in the gastrocnemius, heart and kidney in the ALI-P group when compared to the respective controls. ALI-EX caused a greater thickening of the alveolar walls, more areas of atelectasis and a greater abundance of inflammatory cells in comparison to ALI-P. These results demonstrate that glycogen content in ALI, induced by an herbicide that is highly toxic to humans and animals, is altered in different tissues depending on the location of the injury.