Calcium metabolism in relation to vitamin D and adrenal function in the chick

Abstract

The influence of certain adrenal and synthetic steroids on calcium absorption has been tested in rachitic or vitamin D3-treated rachitic chicks. Long-term (3-day) administration of cortisol or deoxycorticosterone (DOC) interfered with the enhancement of Ca transport generally brought about by vitamin D3. The steroids had no effect on absorption by rachitic chicks. The effect was not a direct antagonism of the vitamin D3 effect, since cortisol, Δ' cortisol, or DOC enhanced the vitamin D3 effect when the steroids were injected intracardially 1 hr before the test. The effects can be correlated with interference of adrenal function when cortisol or DOC are administered for long periods. The theory is proposed that vitamin D3 is transformed into its active form in the adrenal cortex. Use of the specific inhibitor, 1-(2-chlorophenyl)-1-(4-chlorophenyl)-2, 2-dichloroethane, to interfere with adrenal function showed that this substance, when given for 3 days prior to the test, would eliminate the enhancement of Ca transport usually brought about by vitamin D3.