Strontium–calcium discrimination in vitro by rat tissues.

Uptake of 89Sr and 45Ca by 15 soft tissues of adult rat was studied in vitro to assess the extent of discrimination between Sr and Ca. While brain, kidney, placenta and uterus have lower uptake of.89Sr and 45 Ca that of diaphragm, lactating mammary gland, skeletal muscle, skin, spleen and testes is higher. Tissues with medium range uptake are heart, small intestine, liver, lung, non-lactating mammary gland and ovary. The 6 tissues displaying discriminating ability, as expressed by 89Sr/45Ca (tissue/medium), in the decreasing order are: small intestine, kidney, lactating mammary gland, placenta, diaphragm and heart. Non-lactating mammary gland and the other tissues did not differentiate between Sr and Ca. The efect of several enzyme inhibitors, compounds influencing Sr-Ca metabolism and other factors was studied in terms of the nature and mechanism of Sr-Ca discrimination.