AJP - Regulatory, Integrative and Comparative Physiology, Vol 252, Issue 5 1003-R1008, Copyright © 1987 by American Physiological Society
Determination of plasma volume in swine by the enzyme-dilution method
M. A. Holmes and R. B. Weiskopf
Plasma volume of six young swine was determined by simultaneous dilution in
the plasma of two purified porcine enzymes, aspartate aminotransferase
(AST) and alanine aminotransferase (ALT), and Evans blue dye. Ninety-minute
time-activity and time-concentration curves were obtained, and the dilution
spaces of each plasma indicator at the time of injection were estimated by
extrapolation of data from the first 30 min after injection. Plasma volumes
estimated using the two enzymes agreed closely with each other (AST, mean
50.2 ml/kg; ALT, mean 49.8 ml/kg) and were 11% smaller than those
determined using Evans blue dye (mean 56.3 ml/kg). Plasma volumes
calculated from the AST and ALT activities and Evans blue dye concentration
in a sample drawn 5 min after injection very closely approximated those
obtained by extrapolation. These values were comparable to previously
published estimates of plasma volume for swine of equivalent weight.
Endogenous plasma levels of AST and ALT activity were measured in samples
drawn from five swine before and after a 40% blood loss. No significant
change in AST or ALT activities occurred after hemorrhage.
