The effects of simulated increases in body weight for 60 days on robusticity and mineral content of limb bones of hypophysectomized rats.

The purpose of this investigation was to subject separate male and female groups of weanling hypophysectomized rats each to a specific 10% simulated increase in body weight using constant centrifugation, ranging from 1.1G to 2.0G, to study changes in bone robusticity and bone mineral content. (In this paper, "G" is the acceleration due to gravity.) After 60 days of centrifugation at 24 rpm, the rats were killed and the humerus, radius, ulna, femur, and tibia were removed, cleared of soft tissues, weighed, measured, decalcified with EDTA, and reweighed. Bone robusticity was determined using the ponderal index: P.I. = bone length divided by 3 square root bone weight; and bone mineral content (BMC) was determined using the formula: BMC = [(Wu - Wd) divided by Wu] X 100. Tukey's Studentized Multiple Range T Test was used. The data suggest that, for both male and female hypophysectomized rats, bone robusticity is decreased with simulated increases in body weight; also, for males, a bimodal curve describing the relationship between BMC and simulated increases in body weight is suggested.