Inhibition of (beta)-adrenergic-dependent alveolar epithelial clearance by oxidant mechanisms after hemorrhagic shock

Catecholamine release can avert alveolar flooding after severe hemorrhagic shock. To clarify the role of catecholamine in this upregulation mechanism, rats were hemorrhaged to a mean arterial pressure of 30-35 mmHg for 60 minutes before being resuscitated with a solution of 4% albumin, after which alveolar liquid clearance was measured. The results provide direct in vivo evidence that neutrophil-dependent oxidant injury to alveolar cells helps to blocks the upregulation of fluid clearance by catecholamines if no alteration of paracellular permeability to the protein takes place.