TRYPANOCIDAL ACTIVITY AND ARSENIC CONTENT OF RAT BLOOD FOLLOWING INTRAVENOUS ADMINISTRATION OF OXOPHENARSINE HYDROCHLORIDE

¹ Department of Pharmacology, University of Minnesota School of Medicine, Minneapolis

1. By trypanocidal assay of the blood arsenic against an oxophenarsine standard, inactivation of this arsenical by the rat was demonstrable as early as four hours after its intravenous injection.

2. Initially high, trypanocidal activity was barely detectable in blood samples drawn 24 hours after injection despite an average arsenic content greater than that found in samples collected at eight and twelve hours.

3. Since rat blood inactivated oxophenarsine at a considerably slower rate in vitro, extravascular tissues must play a major role in its inactivation in the rat.

4. Preliminary experiments suggest that the inactivation of oxophenarsine in rat blood in vitro occurs in the cellular fraction for which it has a marked affinity. The relative role of erythrocytes and white cells in this phenomenon was not investigated.