RADIOCALCIUM AS AN INDICATOR IN THE STUDY OF THE ACTION OF ESTRADIOL ON CALCIUM METABOLISM

Abstract

The influence of estrogen on Ca metabolism in soft tissues and skeleton was studied in pigeons by the use of radiocalcium. Daily estrogen injns. produce an increase of Ca metabolism to a higher degree than can be observed to occur by normal hormonal secretion. Excretion of Ca is decreased by estrogen injns. and at the same time over-all retention of Ca is increased, yielding a biological half-life of Ca of about 75 days instead of 45 days in the controls. The distr. of Ca in bone was also studied by the radioautographic technic. The new medullary bone of the femur and tibia is very rich in injd. radiocalcium. A comparison is made between Ca and P in bone metabolism.