Blood:bone disequilibrium. III. Linkage between cell energetics and Ca fluxes

Specially designed Ussing chambers were used for the quantitation of fluxes of Ca2+ and lactate ions to and from viable calvaria taken from 2- to 3-day-old rat pups and young adult mice. The latter in vitro support Ca2+ levels comparable to plasma levels in vivo. The effects of various metabolic inhibitors and parathyroid hormone were studied. The results support previous findings that Ca influx into bone is a passive concentration-dependent process not significantly affected by alterations in the energy status of the bone cells. In large measure, the efflux from bone also appears to be passive. However, significant alterations in the calcium levels supported by efflux from bone were observed as acute effects of metabolic inhibitors. Part of the metabolically derived efflux may be attributed to acid production (aerobic glycolysis). However, part must be ascribed to cellular activities not yet defined.