Synthetic [Asu1,7] eel calcitonin increases phosphorus content in the hepatic bile of intact and nephrectomized rats

The effect of synthetic [Asu1,7] eel calcitonin (CT) on phosphorus content in the hepatic bile was investigated in intact and nephrectomized rats. The subcutaneous administration of CT (80 MRC mU/100 g BW) produced a significant fall in the serum inorganic phosphorus concentration and a corresponding increase in the amount of phosphorus in the liver and kidney. These changes were observed even at the lowest dose of CT (40 MRC mU/100 g BW). The phosphorus contents in the spleen, heart, lungs and muscle were not significantly changed by CT administration. CT also provoked a marked elevation of phosphorus excretion into the bile. In nephrectomized rats, CT (80 MRC mU/100 g BW) caused a significant decrease in serum inorganic phosphorus concentration and a remarkable increase in liver phosphorus content. CT markedly increased phosphorus excretion into the bile of nephrectomized rats. These results support the theory that the hypophosphatemic effect of CT may be, at least partly, based on its action on liver in addition to kidney. This effect of CT on the liver may be the cause of increased excretion of phosphorus into the bile.