Plasma disappearance of rabbit alpha2HS-glycoprotein and its uptake by bone tissue

Plasma alpha2HS-glycoprotein is specifically accumulated in calcified tissues. In the present studies this glycoprotein was isolated from plasma and after iodination with iodine-125 was injected intravenously into young rabbits. The tissue distribution and plasma disappearance rate of this radioactively labeled material were determined. Of the various tissues studied, bone showed the greatest retention of labeled glycoprotein expressed as percentage of the injected dose per gram tissue relative to the plasma content. The rate of loss of iodinated alpha2HS-glycoprotein from plasma was similar to that of alpha2HS-glycoprotein labeled endogenously by using 14C-glucosamine or 3H-glucosamine. The uptake of exogenously labeled 125I-alpha2HS-glycoprotein into bone tissue expressed as a percentage of the injected dose was similar to that of endogenously labeled 14C-alpha2HS-glycoprotein. These results suggest that the 125I-labeled material can be used to study further the metabolism of alpha2HS-glycoprotein by bone tissue.