A-205804 is primarily used in scientific research as a selective inhibitor of the epithelial sodium channel (ENaC). It is employed to study ion transport mechanisms in epithelial tissues, particularly in the lungs, kidneys, and colon. Due to its ability to block ENaC activity, it has been investigated for potential therapeutic applications in conditions involving fluid imbalance, such as cystic fibrosis, where excessive sodium absorption contributes to thick mucus formation. Researchers use A-205804 to modulate sodium reabsorption in cellular and animal models, helping to understand disease pathology and evaluate new treatment strategies. Its specificity makes it a valuable tool in pharmacological studies focused on channel function and epithelial physiology.