Studies on osteoporosis I. Experimental models. Effect of age, sex, genetic background, diet, steroid and heparin treatment on calcium metabolism of mice.

C3H/St(Ha) and C57Bl/6(J) mice of both sexes and various ages were exposed to whole body neutron irradiation. The 49Ca generated (half life 8.8 minutes) was immediately determined in a whole body counter. Total body calcium content was calculated. It was assumed that 99% of this represented skeletal calcium. In females, significant decrease in calcium content occurred after 23 months of age. In C3H/St(Ha) mice, low calcium diet, heparin (500 i.u./Kg. b.i.d.) and prednisolone (50 mg/Kg) treatment accelerated calcium loss and produced significant decrease in 3 months. C57Bl/6(J) mice were less susceptible to the latter drugs.