| Abstract: | The relationship between the increase in the blood CFUc concentration after intravenous injection of dextran sulphate (DS) and the pre-existing levels of spontaneously circulating CFUc was studied in dogs. After 15 mg DS/kg body weight the CFUc numbers per ml blood rose by a factor of 3.7 over the pre-injection values, from 78 +/- 11 (SEM) to 359 +/- 50, in normal dogs, and increased by a factor of 3.9 in 0.84-Gy-r-irradiated animals which had a reduced initial CFUc concentration per ml, from 35 +/- 8 to 116 +/- 43. The injection of 20 mg DS/kg body weight into unirradiated dogs caused an increase, by a factor of 11.5, of the pre-injection CFUc concentration, from 101 +/- 20 to 921 +/- 106. On the basis of the mobilization curves for individual dogs, a significant correlation was found between the normal blood CFUc value and the number of CFUc mobilized by DS for both dose levels. From the descending part of the mobilization curves obtained after 15 mg DS/kg body weight, kinetic parameters of canine circulating CFUc were derived. The mean blood transit time (t) was 1.4 +/- 0.5 hr and the half time (T/2) was 1.0 +/- 0.4 hr. |
