Behavior and characterization of blood carbon disulfide in rats after inhalation

Abstract

Studies were undertaken to characterize free and bound CS 2 in the blood of exposed rats. Rats were exposed for 4 hr to CS 2 at concentrations of 0.5, 1.0, 2.0, 3.0, or 4.0 mg/liter. Both free and bound or acid-labile CS 2 (AL CS 2) in the blood increased linearly with inhalation concentration. AL CS 2 in the blood also increased linearly with time when rats were exposed to 2 mg/liter of CS 2 for up to 4 hr. Free CS 2 was eliminated rapidly by a two-exponential, first-order process, with half-times of 8.7 and 55.2 min; AL CS 2 was eliminated similarly but more slowly, with half-times of 2.2 and 42.7 hr. The direct proportionality of blood AL CS 2 concentrations to the inhalation concentrations and exposure time, coupled with the slow AL CS 2 elimination, suggests that blood AL CS 2 may be useful as an indicator of total CS 2 exposure. When rats were exposed to 4 mg/liter of CS 2 for 4 hr, the majority of free and AL CS 2 was in the red blood cells. Dialysis studies with whole blood from CS 2-exposed rats carried out at 4, 26, and 37°C demonstrated the temperature dependence for the release of free and AL CS 2. Plasma and hemolysates of red blood cells from CS 2-exposed rats, dialyzed at 4°C, showed no detectable loss of AL CS 2 from the plasma and only a slight loss from the hemolysate (10%) after 24 hr. These studies indicate that CS 2 binds mainly to macromolecules in blood.