Distribution of 131I-labeled Bothrops erythromelas venom in mice.

Abstract Bothrops erythromelas is responsible for many snake bites in north-eastern Brazil. In the present study we determined the in vivo distribu-tion of the venom following its subcutaneous injection into mice. B.erythromelas venom and albumin were labeled individually with 131 Iby the chloramine T method, and separated in a Sephacryl ® S-200column. The efficiency of labeling was 68%. Male Swiss mice (40-45g), which had been provided with drinking water containing 0.05% KIover a period of 10 days prior to the experiment, were inoculateddorsally (sc) with 0.3 ml (2.35 x 10 5 cpm/mouse) of 131 I-venom (N =42), 131 I-albumin or 131 I (controls, N = 28 each). Thirty minutes and 1,3, 6, 12, 18 and 24 h after inoculation, the animals were perfused with0.85% NaCl and skin and various organs were collected in order todetermine radioactivity content. There was a high rate of venomabsorption in the skin (51%) within the first 30 min compared toalbumin (20.1%) and free iodine (8.2%). Up to the third hour afterinjection there was a tendency for venom and albumin to concentratein the stomach (3rd h), small intestine (3rd h) and large intestine (6thh). Both control groups had more radioactivity in the digestive tract,especially in the stomach, but these levels decreased essentially tobaseline by 12-18 h postinjection. In the kidneys, the distributionprofiles of venom, albumin and iodine were similar. Counts at 30 minpostinjection were low in all three groups (1.37, 1.86 and 0.77,respectively), and diminished to essentially 0% by 12-18 h. Albumintended to concentrate in muscle until the 3rd h postinjection (1.98%).There was a low binding of labeled venom in the liver (<0.54%),thyroid (<0.11%) and lungs (<0.08%), and no iodinated venom wasdetected in brain, heart, diaphragm, spleen or bladder. The low venombinding observed in most internal organs, comparable to that ofalbumin, suggests that B. erythromelas venom does not specificallytarget most internal organs. That is, the systemic effects of envenoma-tion are mainly due to an indirect action.