STUDIES ON THE VERY EARLY DISTRIBUTION OF $sup 45$Ca IN THE TISSUES AND SKELETON OF THE MOUSE

The distribution of calcium-45 in the body at short intervals after intravenous injection was investigated in mice by the low-temperature autoradiographic technique. To correct for effects due to different degrees of vascularization, a control series of mice was given sulfur-35 labeled thiosulfate. Although calcium and thiosulfate ions in general behave very similarly in their extra-skeletal distribution, the higher renal clearance rate of thiosulfate resulted in a relatively higher concentration of this material in the kidney. The rate of exchange with skeletal calcium was consistent with rates deduced from analyses of plasma clearance curves for a rapidly exchangeable bone fraction. (auth)