It has been shown that dimercaprol (2: 3-dimercaptopropanol, BAL) increases the excretion and alters the distribution of lead in rabbits when the dimercaprol is given less than twenty-four hours after intravenous administration of lead acetate (Ginsburg and Weatherall, 1948). This paper extends these observations to a later phase in the distribution of a single intravenous dose of lead. At this phase most of the lead remaining in the body was found in the bones. It seemed likely that dimercaprol would not have much effect on lead so deposited, and, at the suggestion of Professor J. H. Gaddum, the effect of parathyroid extract, which is believed to mobilize lead from bones (Hunter and Aub, 1927), was also examined, alone and in conjunction with dimercaprol.
METHODSThe procedure in these experiments followed that of Ginsburg and Weatherall (1948) with some modifications, as follows: Pb2"0 (radium D) was used as a tracer instead of Pb212 (thorium B), the short halflife of which made it useless for the present purpose. Radium E and radium F were removed from an equilibrium mixture of radium D, E, and F by displacement with nickel, added as foil to a solution in hydrochloric acid. A small quantity of the resulting solution of radium D and some dextrose were added to a solution of lead acetate so that the final solution contained 2.07 mg. Pb and 2-3 microcuries of radium D per ml. in 4 per cent (w/v) dextrose. Doses of 1.0 ml./kg. (i.e., 0.01 mM/kg.) were administered to rabbits of both sexes and various breeds by injection into the marginal vein of one ear at a rate of 2.0 ml. per min. After injection the rabbits were placed in metabolism cages and allowed food and water ad libitum ftbm vessels placed outside windows in the cages so that spilt food or water did not dilute