Purpose: The capacity of the lung to clear edema fluid has been shown to be one of the factors that can influence the prognosis of cardiogenic and noncardiogenic pulmonary edema. Active Na+ transport across the alveolar epithelium is the main driving force involved in this physiological process. Since endogenous catecholamines are known to activate the sodium-dependent mechanism of alveolar edema clearance, the objective of the present study was to explore if adrenalectomy, which prevents the release of endogenous catecholamines and other hormones, such as corticosterone, into circulation, would affect edema resolution in a model of lung injury induced by thiourea.
Methods: A high-permeability pulmonary edema was induced in adult male Sprague-Dawley rats using a thiourea-induced pulmonary edema model. To determine if the release of adrenalin and corticosterone is essential for resolution of the thiourea-induced edema, we measured 1) the release of adrenalin and corticosterone in urine and 2) edema resolution in control animals and adrenalectomized animals.
Results: The administration of thiourea significantly increased the wet-to-dry ratio after four and eight hours. After 12 and 24 hours, the wet-to-dry ratio gradually returned to baseline. Although thiourea-induced pulmonary edema was associated with a significant increase in urine adrenalin and corticosterone, the absence of adrenalin and corticosterone response in adrenalectomized animals did not prevent the resolution of the edema.
Conclusions: These experiments demonstrated that resolution of thioureainduced pulmonary edema can occur in the absence of hormonal secretion by the adrenal glands.