EFFECT OF DMPS AND VARIOUS ADSORBENTS ON THE ARSENIC EXCRETION IN GUINEA-PIGS AFTER INJECTION WITH AS2O3

The present experiments were performed to test the possibility of inte rrupting the enterohepatic circulation of arsenic (As). Therefore the efficacy of adsorbents to bind As and/or As-DMPS adducts in vitro and their effect on the excretion of As into the feces and urine in vivo w ere investigated after injection of As2O3 and DMPS in guinea-pigs. The adsorbents bentonite, activated charcoal or colestyramine, respective ly, were tested. Only slight binding of As-73 (< 5% of the As-73 dose) was observed to all adsorbents in vitro. After addition of DMPS, a go od binding was found for As-73 to colestyramine (50%) or activated cha rcoal (60%), respectively. However, the As-73-DMPS adduct was removed from the activated charcoal during washing. In the first in vivo exper iment, male guinea-pigs (n = 4/group) received As2O3 [0.02 mmol As(III )/kg s.c. labelled with a tracer dose of As-73(III) (0.14 kBq/g)], 30 min later DMPS (0.1 mmol/kg i.p.) and by gastric tube (10 ml/kg body w t) either saline, bentonite (1 g/kg), activated charcoal (1 g/kg) or c olestyramine (0.2 g/kg), respectively. Urine and feces were collected for 24 h. No increase in As-73 excretion into the feces was observed a fter administration of DMPS and all adsorbents, compared to control an imals. In the second in vivo experiment male guineapigs (n = 4/group) received the same As2O3 (+ As-73)- and DMPS dose. In addition, with a gastric tube (10 mmol/kg) saline, colestyramine (0.2 g/kg), DMPS (0.1 mmol/kg), or the combination of DMPS (0.1 mmol/kg) + colestyramine (0. 2 g/kg) were administered according to the scheme given in the followi ng table. The amount of feces excreted did not differ between groups. Excretion of As-73 within the feces during the first 12 h after As inj ection is shown in the following table (mean +/- SEM). The same amount of As-73 (34% of the As-73 dose) was excreted into the urine from ani mals in groups 4 and 5 during this time. Obviously, the combined oral administration of DMPS + colestyramine markedly enhanced fecal excreti on of As mobilized by DMPS i.p. It is suggested that interruption of e nterohepatic circulation of As may be a valuable adjunct in the treatm ent of As poisoning.