Effect of hyperbaric oxygenation on bone in HEBP-induced rachitic rats.

The effect of hyperbaric oxygenation (HBO) treatment on rachitic change was studied using 4-wk-old, 1-hydroxyethylidene-1, 1-bisphosphonic acid disodium (HEBP-EHDP)-induced rachitic rats. After treatment, the dry weight, ash weight, Ca and P content, and bone mineral density of the hind leg bones were measured in each rat. These parameters were significantly increased in the rats that were treated with HBO after HEBP administration compared with those parameters in the rats that received HEBP alone. However, there was no significant differences between the rats treated simultaneously with HEBP and HBO and those that were treated with HEBP alone. These results were consistent with radiologic and histologic findings. Marked calcification in the center of the growth plate was revealed in the rats treated with HBO after HEBP administration. We suggest that intermittent high-pressure pure oxygen has a beneficial effect on osteogenesis in rachitic bone but does not prevent rachitic change.

Bone composition and metabolism after hyperbaric oxygenation in rats with 1-hydroxyethylidene-1,1-bisphosphonate-induced rickets.

We examined bone composition and metabolism after hyperbaric oxygenation (HBO) in Wistar rats with 1-hydroxyethylidene-1, 1-bisphosphonate (HEBP)-induced rickets. Twenty rats at 4 wk of age were divided into four groups of five rats each. The HEBP + HBO group received high dose (50 mg.kg-1.day-1) HEBP injections subcutaneously for 7 days and were then exposed to HBO for 7 days. The HEBP group received only high dose HEBP injection for the first 7 days. Control group A received neither HEBP nor HBO. Control group B received no HEBP injection and was exposed to HBO only for the second 7 days. Both bone mineral and hydroxyproline contents significantly increased in rats in the HEBP + HBO group as compared with the HEBP group. Alkaline phosphatase activity of bone, which is a marker of osteoblastic activity and bone formation, was high in the HEBP + HBO and HEBP groups compared with control groups A and B, although there was no difference between the former two groups. On the other hand, tartrate-resistant acid phosphatase activity, which is a marker of bone resorption, was lower in the HEBP + HBO group than in the HEBP group. These findings suggest that HBO suppresses bone resorption in high osteoblastic activity after the cessation of HEBP administration, and this phenomenon increases total bone mass.