Chicken Osteoclasts Do Not Possess Calcitonin Receptors

Osteoclasts freshly isolated from embryonic chicks have been examined for calcitonin receptors using radio-iodine-labeled salmon calcitonin. Calcitonin binding to chick osteoclasts could not be shown by either autoradiography or biochemical binding studies. Furthermore, calcitonin did not stimulate cyclic AMP production. By contrast, rat osteoclasts have abundant calcitonin receptors, and a sensitive cyclic AMP response to calcitonin has been shown previously. It is concluded that chick osteoclasts do not possess calcitonin receptors, a finding which could explain the lack of calcitonin responsiveness observed in other avian osteoclast culture systems.