Catecholamine clearance from alveolar spaces of rat and human lungs
ABSTRACT Although aerosolized beta-adrenergic agonists have been used as a therapy for the resolution of pulmonary edema, the mechanisms of catecholamine clearance from the alveolar spaces of the lung are not well known.
To determine whether catecholamine clearance from the alveolar spaces is correlated with the fluid transport capacity of the lung.
Albumin solution containing epinephrine (10(-7)M) or norepinephrine (10(-7)M) was instilled into the alveolar spaces of isolated rat and human lungs. Alveolar fluid clearance rate was estimated by the progressive increase in the albumin concentration over 1 h. Catecholamine clearance rate was estimated by the changes in catecholamine concentration and alveolar fluid volume over 1 h.
The norepinephrine clearance rate was faster than the epinephrine clearance rate in the rat and human lungs. In the rat lungs, amiloride (a sodium channel blocker) caused a greater decrease in alveolar fluid clearance and epinephrine clearance rate than propranolol (a nonselective beta-adrenergic antagonist). Although propranolol and phentolamine (an alpha-adrenergic antagonist), and 5-(N-ethyl-N-isoprophyl)amiloride (a Na+/H+ antiport blocker) changed neither the alveolar fluid clearance nor the norepinephrine clearance rate, amiloride and benzamil (a sodium channel blocker) decreased both clearance rates. As in the rat lungs, amiloride decreased alveolar fluid and norepinephrine clearance rates in the human lungs.
These results indicate that the catecholamine clearance rate from the alveolar spaces is correlated with alveolar fluid clearance in rat and human lungs.
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ABSTRACT: Tesis Univ. Granada. Departamento de Medicina. Leída el 25 de mayo de 2006
- Respiration 02/2007; 74(1):118-20. DOI:10.1159/000096836 · 2.92 Impact Factor
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ABSTRACT: Acute pancreatitis causes pulmonary oedema with the accumulation of fluid in the alveolar spaces, possibly due to reduced clearance. This study tested the hypothesis that acute pancreatitis decreases alveolar fluid clearance in a rat model of pulmonary oedema during acute pancreatitis. Acute pancreatitis was induced by a retrograde injection of 5% taurocholate sodium (0.2 mL) into the common bile duct. The lungs were isolated 4, 24 and 48 h after the induction of acute pancreatitis and alveolar fluid clearance was measured in the absence of pulmonary perfusion. Alveolar fluid clearance increased to 31.0 +/- 3.5% of instilled volume/h in rats with acute pancreatitis for 4 h compared with 17.3 +/- 1.0% of instilled volume/h in sham rats (P < 0.01), then returned to the control level 48 h after acute pancreatitis (16.0 +/- 4.1% of instilled volume/h). In contrast, the lung water to dry lung weight ratio decreased maximally 24 h after acute pancreatitis (P < 0.01), then returned to the control level 48 h after acute pancreatitis. The plasma epinephrine levels increased to 25-fold higher in rats with acute pancreatitis for 4 h than in sham rats without acute pancreatitis. Prazosin (an alpha(1)-adrenergic antagonist, 10(-4) mol/L), yohimbine (an alpha(2)-adrenergic antagonist, 10(-4) mol/L) or a bilateral adrenalectomy inhibited the increase in part, a combination of prazosin (10(-4) mol/L) and yohimbine (10(-4) mol/L) completely inhibited the increase in alveolar fluid clearance in rats after acute pancreatitis for 4 h, whereas propranolol (a beta-adrenergic antagonist, 10(-4) mol/L) had no effect. Endogenous catecholamine stimulates alpha-adrenoceptors and increases alveolar fluid clearance in rats with acute pancreatitis.Respirology 12/2008; 14(2):195-202. DOI:10.1111/j.1440-1843.2008.01453.x · 3.50 Impact Factor