Concentration And Distribution Of 210Po And Its Effects On The Expression Of Vascular Endothelial Cell Growth Factor (VEGF) In Rats Exposed To Radon

Object: Increasingly importance has been attached to the hazard from radon and itsdaughters. But there is no detailed report of the Concentration and distribution of ²¹⁰Po andthe impact on cytokines, especially on VEGF after radon exposure. So the Concentrationand distribution of ²¹⁰Po and changes of vascular endothelial cell growth factor(VEGF) inlung, liver and femur in rats exposed to radon were studied in this experiment, to providedosimetric and molecules basis for further studies on the carcinogenic effect of radon andits daughters.Methods: Twenty male Wistar rats were randomly divided into four groups, includingone control group and three radon exposed groups with the cumulative doses of 100 WLM(low dose), 200 WLM(middle dose) and 400 WLM (high dose) respectively. Tissuesamples containing ²¹⁰Po were spontaneously deposited onto silvery discs with thediameter of 20 mm by means of wet ashing and electrodeposition. The concentration of²¹⁰Po in tissues were measured byαspectroscopy, and tissue burden were calculated. Thelung, liver and femur of 4 groups were homogenized and the proteins were extracted. Thechanges of VEGF in lung, liver and femur were observed by means of western blot.Results:â‘ The concentrations of ²¹⁰Po were significantly different among the four dosegroups in hair, sex gland, liver and femur (P＜0.01) and in spleen and kidney (P＜0.05). The concentrations of ²¹⁰Po were different between the exposed groups and thecontrol group in lung and soleus muscle (P＜0.05) but no difference between the exposedgroups. There were different between 400 WLM exposed group and the others in heart andsmall intestine(P＜0.05). No differences were found in other organs or tissues. Theconcentrations of ²¹⁰Po in lung, spleen and hair were higher than those of in liver andbone, with that in intestine the lowest.â‘¡The tissue burdens of liver, bone and sex gland were significantly different from those in other organs or tissues. Tissue burdens wereincreased with the exposure dose of radon and its daughters.â‘¢The expressions of VEGF inlung and liver increased gradually with the dose of radon and its daughters. There weredifferent in lung between control group and exposed groups, with 200 WLM and 400WLM exposed groups (P＜0.01), 100 WLM exposed group (P＜0.05). In liver, therewere different between control group and 200 WLM and 400 WLM exposed groups (P＜0.01), but no difference with 100 WLM. Compared to control group, the expressions ofVEGF in femur slightly declined in 100 WLM and 200 WLM exposed groups, but therewere no difference. And there was difference between control group and 400 WLMexposed group (P＜0.01).Conclusion:1. ²¹⁰Po was mainly distributed in spleen, hair, sex gland, lung, femur and liver. Theconcentrations of ²¹⁰Po in organs or tissues and the tissue burdens were correspondinglyincreased with the exposure dose of radon and its daughters. The results of this experimentprovided a dosimetric basis for further studies on the carcinogenic effect of radon and itsdaughters.2. The expression of VEGF was increased with the exposure dose of radon and itsdaughters, especially in high dose exposure group. It indicated that VEGF not only playedan important role in the development of radiation induced inflammation, but alsoperformed active functions on the devel -opment of radon induced carcinomas.3. VEGF may be a early distinctive and specific marker of radiation effects of radon and itsdaughters.