Learning Objective #1: Identify the effect of progressive exercise on emphysema induced hamster diaphragms

Learning Objective #2: Describe the effect of acute inspiratory resistant loading on the diaphargm of emphysema induced hamster diaphragms

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In emphysema (EMP), lung hyperinflation due to loss of lung elastic recoil and dynamic hyperinflation due to incomplete lung emptying that imposes a chronic persistent load on the diaphragm and impairs its mechanical efficiency. Patients with EMP must generate higher than normal inspiratory pressures with each breath. During acute exacerbations, diaphragm fatigue (DF) may develop due to decreased contractility and increased lipid peroxidation. EMP induces production of reactive oxidative species (ROS) in the diaphragm due to the chronic persistent load. Overproduction of ROS occurs during muscle fatigue and lead to a pathological form of oxidative stress perpetuating muscle contraction dysfunction leading to diaphragm fatigue and respiratory failure. Exercise training improves contractile properties and endurance in both normal and EMP diaphragm but it is unclear if this improvement is accompanied by changes in lipid peroxidation. Results of a study investigating the effect of conditioning exercise on the development of DF in EMP hamster and lipid peroxidation during DF will be presented. Forty adult Golden Syrian hamsters were used to provide an adequate sample size. Hamsters radomly received either porcine pancreatic elastase (PPE) to produce EMP or saline (0.5ml) instilled intratracheally. Four experimental groups included: Group 1 saline sedentary; Group 2 emphysema sedentary, Group 3 saline exercise and Group 4 emphysema exercise. Groups 3 and 4 received a 12-week progressive exercise-conditioning program consisting of treadmill running at a 20% grade for 900 seconds/day (1,090 m/hr), 5 days/week. Groups 1 and 2 were not exercised. Following the 12-week exercise period, inspiratory resistance loading was induced to produce DF. Diaphragm shortening was measured. Following the experiments, the diaphragms were harvested and GSH/GSSG ratios measured. The research project was funded by a grant from the Arkansas Bioscience Institute Grant No. 0112-04038-22-0000.