Factors Influencing 45 Ca Metabolism in Brain and Other Organs in Vivo 1

Abstract

Summary

The distribution of ⁴⁵Ca among various tissues of the rat was followed for 8 hr after intravenous administration of the isotope. Three major patterns of ⁴⁵Ca turnover were demonstrable, represented by: (i) brain; (ii) bone; and (iii) certain soft tissues: kidney, adrenal, and muscle. These differences may be explained in terms of different exchange (e.g., for bone) and physiological barriers (e.g., for brain). Studies on the subcellular distribution of ⁴⁵Ca in brain, performed 2 hr after intravenous administration of ⁴⁵CaCl₂, showed that mitochondria accumulated 25% of the total ⁴⁵Ca; moreover, the concentration of the ⁴⁵Ca accumulated by the mitochondria was decreased by prior administration of phenobarbital and of reserpine, but increased by pentylenetetrazol.