THE KINETICS OF THE ELIMINATION OF THE DYE WATER BLUE FROM DOG PLASMA AFTER INTRAVENOUS INJECTION

Abstract

The plasma conc. of water blue (a non-toxic triphenyl methane dye which remains in dog''s plasma after in-traven. injection longer than other known dyes) in 6 dogs was measured over a 12-day period after intraven. injection. During the first 2-3 days, the conc. decreased exponentially with time, the conc.-time curve being represented by 2 exponential curves, one representing rapid and the other slower diffusion from the blood stream. After 3-4 days, the elimination is linear with time, the general curve being Ct = Ae-at + Be-bt [long dash] vt + D, where Ct is the plasma conc. at any time t after injection, and A, a, B, b, v and D are constants. The dye conc., measured at hourly intervals over a 4-hr. period 6-7 days after the injection, shows an apparent decrease of 10-15%, whereas the theoretical decrease from the elimination curve gives a 2% decrease. The Hb also decreases during this period, indicating an increase of plasma volume, perhaps caused by disturbances due to withdrawal of arterial blood.