Discrimination between low dietary zinc and endotoxin exposure : a model study on weaning rats

To establish a parameter for zinc status that is independent of the occurrence of infection, we studied the effects of low dietary zinc and endotoxin in weaning rats 21 d after 65Zn intubation. We monitored aspects of zinc status (tissue zinc content, 65Zn distribution, and specific 65Zn activity in tissue) and 65Zn metabolism (absorption, excretion, and biologic half-life), as well as weight gain, feed conversion, and dietary zinc use. The low zinc diet iuduced classical deficiency with losses of bone zinc, resulting in lower content (7.4 versus 19.6 [mu]mol) and higher specact (17 versus 8 kBq/[mu]mol). Other tissue-specific and plasma-specifie activities were also higher (overall, 20 versus 8 kBq/[mu]mol; plasma, 8 versus kBq/[mu]mol). Endotoxin caused lower total-plasma zinc (0.04 versus 0.05/[mu]mol) but did not affect spec act (4 kBq/[mu]mol): combined endotoxin and low-zinc diet caused low total-plasma zinc (0.01 [mu]mol) and high spec act, as did the low-zinc diet alone (12 kBq/[mu]mol). We conclude that plasma-spec act (or stable isotope enrichment) can serve as an index for nutritional zinc status during recurrent infection. (Pediatr Res 28: 332-335,1990)