MECHANISM OF ACTION 1. Role of c-AMP: Calcitonin binds to specific calcitonin receptors on the plasma membrane of bone osteoclasts and renal tubular epithelial cells, activates adenyl cyclase

1. Role of c-AMP: Calcitonin binds to specific calcitonin receptors on the plasma membrane of bone osteoclasts and renal tubular epithelial cells, activates adenyl cyclase which increase c-AMP level which mediates the cellular effect of the hormone. This is the principal mechanism by which calcitonin acts. 2. Celluar Shift: It has been suggested that calcitonin may directly affect the relative distribution of bone cells. The hormone both in vitro and in vivo produced a celluar shift, in which the number of osteoclasts decreased. 3. PH change: Calcitonin may regulate PH at cellular level producing more alkaline medium which diminishes resorption. METABOLIC ROLE