A comparison of chloride, bromide, and sucrose dilution volumes in neonatal pigs.
Use of 36Cl, 82Br, and [3H]sucrose to estimate extracellular water volume was evaluated in 14 piglets (7-14 days old). 36Cl and 82Br were distributed in approximately the same volume, but a period of 5-6 hr after injection was required to reach equilibrium in the neonatal pig. Dilution volumes calculated before equilibration (2-5 hr) for 36Cl (326 +/- 11 ml/kg) and 82Br (328 +/- 13 ml/kg) were different from equilibration (6-8 hr) phase volumes (356 +/- 13 ml/kg and 355 +/- 13 ml/kg, respectively; P less than 0.001). A 3-hr sample estimated the same volume distribution calculated by extrapolation of the 6- to 8-hr period because of the relationship between the two slopes of the plasma clearance curves. After the 82Br and 36Cl had achieved equilibration, each was distributed in a volume equivalent to total body chloride space (362 +/- 29 ml/kg) measured by neutron activation; no statistical differences were found (P = 0.6). The early equilibration phase measured a 10% smaller, faster exchangeable fraction of total body Cl. Sucrose dilution volume (332 +/- 19 ml/kg) required multiple plasma samples for extrapolation and measured a dilution volume 7% smaller (P less than 0.05) than total body chloride space.
Mørkeberg
J C
JC
United States Department of Agriculture, Agricultural Research Service, Department of Pediatrics and Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas 77030.
Sheng
H P
HP
Huggins
R A
RA
D000818:Animals; D001966:Bromine / Q000493:pharmacokinetics*; D002713:Chlorine / Q000493:pharmacokinetics*; D005110:Extracellular Space / Q000378:metabolism; D008657:Metabolic Clearance Rate; D010949:Plasma / Q000378:metabolism; D013395:Sucrose / Q000493:pharmacokinetics*; D013552:Swine; D014556:Urine / Q000737:chemistry
D002713:Chlorine; D013395:Sucrose; D001966:Bromine