Abstract
A counter migration of 32P but not of 45Ca occurred across a diaphragm of bone subjected to 3 mA of direct current for 8 hrs in 0.01 M HEPES, 5.2% glucose, pH 7.30. It is postulated that these results reflect the affinity of an immobile negatively-charged matrix of bone for calcium, the presence of positively-charged phosphate-containing molecular species such as Ca2H2P04+, and the electroosmotic movement of water. Bone appeared to have a greater affinity for calcium than for phosphate ions at pH 7.30, in the presence or absence of a direct electrical current.