Adrenal Epinephrine Increases Alveolar Liquid Clearance in a Canine Model of Neurogenic Pulmonary Edema

Abstract

Case reports of neurogenic pulmonary edema (NPE) often indicate that the edema resolves quickly. Because plasma epinephrine concentration may be elevated in NPE, and epinephrine has been shown to increase the rate of alveolar liquid clearance (ALC), we determined if ALC was increased in a canine model of NPE produced by the intracisternal administration of veratrine. ALC was determined by instilling autologous plasma into a lower lung lobe and using the increase in instillate protein concentration after 4 h to calculate the volume of fluid cleared from the airspaces by mass balance. To prevent pulmonary hypertension and edema, which would confound the mass balance analysis, carotid arterial blood was allowed to drain into a reservoir as pulmonary arterial pressure started to rise after veratrine administration. ALC in animals administered veratrine (n = 6) was 30.4 +/- 1.6 (SE)% of the instilled volume compared with 14.1 +/- 2.1% observed in control animals. The increase in ALC could be inhibited by adrenalectomy, beta2-adrenergic blockade using ICI 118,551, or sodium channel blockade using amiloride and could be duplicated by infusing epinephrine to increase plasma epinephrine concentration to levels observed in NPE. These data indicate that the increased ALC was mediated by adrenal epinephrine and suggest that edema resolution in patients with NPE might be accelerated by endogenous epinephrine.

The Hemodynamic Mechanisms of Lung Injury and Systemic Inflammatory Response Following Brain Death in the Transplant Donor

“…This damage may be reversible with time. Animal studies have shown that high levels of circulating epinephrine, which are released by the adrenals for some time after the initial sympathetic discharge, can increase alveolar fluid clearance via b 2 -adrenergic stimulation of type II alveolar epithelial cells and lead to recovery from NPE (45,46). This could be enhanced in humans with aerosolized b 2 -adrenergic treatment (47).…”

Protective effect of endogenous β-adrenergic tone on lung fluid balance in acute bacterial pneumonia in mice

“…can increase the capacity of the alveolar epithelium to remove alveolar edema fluid in septic shock, hypovolemic shock, and neurogenic injury (18,30,35,36). However, the effect of endogenous catecholamines in the presence of severe acute bacterial pneumonia on alveolar fluid clearance and lung fluid balance has not been well studied.…”

“…EARLIER EXPERIMENTAL WORK established that elevated endogenous epinephrine levels can increase the capacity of the alveolar epithelium to remove alveolar edema fluid in the setting of septic or hemorrhagic shock (29,35,36) or after an acute neurogenic insult (18). However, the effects of endogenous ␤-adrenoceptor tone on lung fluid balance have not been studied in acute severe bacterial pneumonia, the most common cause of clinical acute lung injury (10).…”

Lung Epithelial Fluid Transport and the Resolution of Pulmonary Edema

“…Although terbutaline increased pulmonary blood flow, this effect was not important, since control studies with nitroprusside, an agent that increased pulmonary blood flow, did not increase fluid clearance. Other studies have demonstrated that ␤-adrenergic agonists increased fluid clearance in rat (164), dog (28,191), guinea pig (258), mouse (121, 124, 155), as well as human lung (307,308). The presence of ␤ 1 -and ␤ 2 -receptors on alveolar type II cells has been demonstrated in vivo by autoradiographic and immunochemistry techniques (19,98,201).…”