Plasma ANP levels and protein extravasation during graded expansion with equilibrated whole blood

• Published in: The American journal of physiology Vol. 271; no. 3 Pt 2; p. R601
• Main Author: Tucker, V L
• Format: Journal Article
• Language: English
• Published: United States 01.09.1996
• Subjects: Animals; Atrial Natriuretic Factor - blood; Blood Proteins - analysis; Blood Transfusion; Blood Volume; Capillary Permeability; Central Venous Pressure; Male; Rats; Rats, Wistar; Serum Albumin, Bovine - pharmacokinetics
• ISSN: 0002-9513
• DOI: 10.1152/ajpregu.1996.271.3.R601

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.