Blood-gas barrier (None in broad scientific use; sometimes referred to as "BGB" in some publications, but not universally standardized)

The blood-gas barrier is a critical, extremely thin (typically 0.2–2 μm) trilaminar membrane located in the gas-exchanging regions of the lungs[2][4][7]. It consists of: - A layer of *alveolar epithelial cells* (primarily type I pneumocytes) - A *basement membrane* (extracellular matrix with type IV collagen, elastin, and proteoglycans) shared between cell layers - A layer of *capillary endothelial cells* Its design allows for efficient diffusion of respiratory gases while maintaining strength to withstand the mechanical forces of breathing. Damage to this barrier can result in leakage of blood or plasma into alveolar spaces (pulmonary edema, hemoptysis), and it plays a central role in lung pathologies related to impaired gas exchange[2][1][4][6][8]. The structure is regulated and maintained through complex cellular and matrix remodeling, ensuring both functionality and integrity under physiological stress[1][5][6]. In summary, the pulmonary capillary blood-gas barrier is not a conventional molecular target, but an anatomical structure whose integrity is essential to respiratory function. Its role in disease is indirect, as the site of injury or dysfunction rather than as a protein or receptor to be targeted by drugs[2][1][4].

Other names

Alveolar-capillary barrierBlood–air barrierAir–blood barrier

Not applicable; no drugs directly act on the blood-gas barrier as a molecular target