title: Plasma ANP levels and protein extravasation during graded expansion with equilibrated whole blood.
abstract: The relationship between plasma immunoreactive atrial natriuretic peptide (irANP) and radiolabeled albumin clearance (CBSA) in multiple tissues after graded volume stimuli was examined. To obtain a pure volume stimulus, pentobarbital sodium-anesthetized rats (5 or 6 per group) were equilibrated with a reservoir of blood by a femoral arteriovenous shunt, and volume expansion (VE) was produced by adjusting reservoir outflow. Peak increases in central venous pressure (CVP) during VE equal to 2 and 4% of the body weight over 5 min were 3.6 +/- 0.2 and 7.0 +/- 0.3 mmHg, and plasma irANP levels measured at 40 min post-VE were elevated 1.9- and 4.1-fold above baseline, respectively. Graded increases in CBSA measured between 5 and 35 min post-VE occurred in selective tissues, including intestine, visceral fat, lung, and muscle (P < or = 0.05). In separate animals, the level of VE was maintained after 2% VE by slower administration of an additional 2% VE for the remaining 30 min. This resulted in a more sustained CVP elevation and larger increases in irANP levels and CBSA compared with either 2 or 4% VE. Furthermore, equations derived from previous work in this laboratory involving intravenous administration of ANP predicted the magnitude of CBSA elevation during maintained VE. These findings support a role for ANP in regulating transcapillary protein distribution during acute intravascular expansion.
authors.affiliation: Department of Human Physiology, University of California, Davis 95616, USA.
authors.forename: V L
authors.initials: VL
authors.lastname: Tucker
mesh_terms: D000818:Animals; D009320:Atrial Natriuretic Factor / Q000097:blood*; D001798:Blood Proteins / Q000032:analysis; D001803:Blood Transfusion; D001810:Blood Volume; D002199:Capillary Permeability; D002496:Central Venous Pressure; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D012710:Serum Albumin, Bovine / Q000493:pharmacokinetics*
chemical_list: D001798:Blood Proteins; D012710:Serum Albumin, Bovine; D009320:Atrial Natriuretic Factor