Nitric oxide and the collagenous protein biosynthesis of irradiated chick chorioallantoic membrane

To study the effect of irradiation doses (2 Gy and 5 Gy) on the rate of collagenous protein biosynthesis (CPB) of chick embryo chorioallantoic membrane (CAM) and to investigate the possible role of the nitric oxide (NO) synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME), its inactive enantiomer D-NAME and the NO donor sodium nitroprusside (SNP) in this effect.

The originally established CAM angiogenesis model was used with few modifications described earlier. The CAM areas were irradiated on the 10th or the 14th day of embryo development with a single dose of 2 or 5 Gy and the CPB was determined 6 h later. L-NAME, D-NAME and SNP were added to the CAM after the irradiation.

The experiments didn't show any significant differences in almost all of the treatment courses. In the 10-day CAM preparations the irradiation not significantly (NS) inhibited the CAM CPB, whereas L-NAME abolished this effect only in the case of 2 Gy dose (NS). The addition of SNP or D-NAME in the post-irradiated 10-day CAM exerted radiosensitization that was significant only in the case of the combination of D-NAME with the 5 Gy dose. There was no significant effect on the respective treatments of the 14-day CAM. The CPB of the 14-day CAM was significantly lower with regard to the values of the 10-day CAM.

The biochemical evaluation of the CAM (CPB method) seems to be not suitable for radiobiological studies. Nevertheless, the implication of NO in the X-ray induced antiangiogenicity cannot be excluded.