The change of subcellular
phosphorus content in the liver was investigated after a single sc administration of synthetic [Asu1,7]
eel calcitonin (CT) to fed rats. Administration of CT (80 MRC mU/100 g
body weight) produced a significant increase in
phosphorus content in the mitochondrial fraction, while this increase was not observed in fractions containing plasma membrane, nuclei, microsomes and cytosol. A significant increase in the mitochondrial
phosphorus content was observed even at the lowest dose of CT (40 MRC mU/100 g
body weight). A single ip administration of
2,4-dinitrophenol (0.1 mg/100 g
body weight), an inhibitor of oxidative phosphorylation, did not prevent significant increases in
phosphorus contents of the homogenate and the mitochondria caused by administration of CT (80 MRC mU/100 g
body weight), although the
drug markedly inhibited
ATPase activity in the mitochondria. Administration of CT did not produce a significant alteration in the mictochondrial
ATPase activity. These results suggest that
phosphorus taken up by the liver cells after CT administration is largely located in the mitochondria, and that this increase is not related to oxidative phosphorylation. Presumably the hepatic mitochondria play a role in the storage of intracellular
phosphorus increased by CT.