Influence of the parathyroids and ultimobranchial glands in the frog ( Rana pipiens) during respiratory acidosis

Abstract

The influence of the parathyroids and ultimobranchial glands on the calcium carbonate deposits of the paravertebral lime sacs was examined in Rana pipiens, and correlated with the systemic buffering capacity during a period of respiratory acidosis. Serum composition of intact, ultimobranchialectomized (UBX), parathyroidectomized (PTX) and PTX-UBX frogs was examined over a 72-hr period during exposure to 10% CO 2-90%O 2. In a high carbon dioxide atmosphere, all groups displayed a respiratory acidosis after 6 hr. At 72 hr, controls showed complete compensation and retained an elevated pCO 2. Frogs without parathormone (PTX) and UBX-PTX frogs continued to exhibit an uncompensated respiratory acidosis and elevated pCO 2 after 72 hr, and displayed tetany. Serum carbonate levels fell in all groups during the first 6 hr but failed to return to pretreatment levels in PTX- and UBX-PTX frogs. The inability of PTX frogs to mobilize calcium carbonate stores under normal and high carbon dioxide atmosphere suggests that parathyroids in amphibians influence a systemic buffering system in addition to ionized calcium.