title: Alveolar liquid clearance is increased by endogenous catecholamines in hemorrhagic shock in rats.
abstract: The primary objective of this study was to test the hypothesis that hemorrhagic shock would stimulate alveolar liquid clearance by a catecholamine-dependent mechanism. Anesthetized rats were hemorrhaged to a mean arterial pressure of 30 mmHg for 90 min, but they were not resuscitated. Alveolar liquid clearance was measured by the concentration of labeled and unlabeled protein over 2 h in an isosmolar physiological solution of 5% albumin that had been instilled into one lung. Hemorrhaged rats developed a severe metabolic acidosis that was associated with a 5- to 10-fold rise in plasma epinephrine levels. There was a 60% increase in alveolar liquid clearance in the hemorrhaged rats compared with control rats (55 +/- 6 vs. 34 +/- 7%; P < 0.05). Amiloride (10(-4) M) or propranolol (10(-4)M) inhibited the increase in alveolar liquid clearance. Thus the endogenous release of catecholamines associated with hemorrhagic shock markedly stimulates alveolar fluid clearance by a beta-adrenergic-mediated stimulation of active sodium transport. These data suggest a new, previously unrecognized mechanism that may protect against alveolar flooding in the acute phase of hemorrhagic shock.
authors.affiliation: Department of Anesthesia, University of California, San Francisco 94143, USA.
authors.forename: J F
authors.initials: JF
authors.lastname: Pittet
authors.forename: T J
authors.initials: TJ
authors.lastname: Brenner
authors.forename: K
authors.initials: K
authors.lastname: Modelska
authors.forename: M A
authors.initials: MA
authors.lastname: Matthay
mesh_terms: D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D001826:Body Fluids / Q000378:metabolism*; D002395:Catecholamines / Q000097:blood / Q000378:metabolism*; D004232:Diuretics / Q000494:pharmacology; D004727:Endothelium / Q000502:physiology; D004837:Epinephrine / Q000097:blood; D008297:Male; D011650:Pulmonary Alveoli / Q000378:metabolism* / Q000503:physiopathology; D011654:Pulmonary Edema / Q000503:physiopathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012771:Shock, Hemorrhagic / Q000378:metabolism* / Q000503:physiopathology
chemical_list: D002395:Catecholamines; D004232:Diuretics; D000584:Amiloride; D004837:Epinephrine