Abstract
Cruess and Clark (1) studied the effect of hypervitaminosis D on the phospholipids of diaphyseal and metaphyseal long bone. All major phospholipid fractions were increased, and incorporation of 32P into these fractions was enhanced. This study is concerned with the effect of parathyroid hormone administration on the concentration of total lipid, phospholipid, and 32P incorporation into phospholipid in bone.
Materials and Methods. Male CFN rats (130-150 g, Carworth, Inc.) were maintained on a regular diet of Lab-Blox and water ad libitum. Parathyroidectomy was performed by the cautery procedure of Munson (2) 2-4 days prior to hormone treatment. 1 Control animals compared with parathyroid extract-treated animals were injected with a corresponding volume of solvent: 1.2% glycerol, 0.7% bovine serum albumin, and 0.2% phenol in physiological saline. Carrier-free H3 32PO4, glycerol-1,3-14C(10.6 mCi/mmole), ethanolamine-172-14C(3.7 mCi/mmole) and l-serine-14C(U) (7.5 mCi/mmole) were purchased from New England Nuclear Corp. and Nuclear Chicago. Bones were prepared and incubated according to Cruess and Clark (3). Femora and tibias were removed and the marrow cavity was flushed out by washing with a stream of cold saline through a fine needle. Tissues were incubated in 4 ml of Krebs-Henseleit bicarbonate buffer containing 10 mM glucose. H3 32PO4, glycerol, and serine were present in appropriate incubation mixtures at a concentration of 1.0 μCi/μmole/ml. Ethanolamine was added at 0.5 μC/μ-mole/ml.
In experiments testing metabolic inhibitors, only a single tibia and femur were incubated in each flask; in all other experiments paired femora and tibias were used. All incubations were done at 37° for 4 hr. The gas phase was 95% oxygen-5% CO2, except when the anaerobic effect of 95% N2-5% CO2 was evaluated. Bones for lipid extraction were pulverized in a mortar with Dry Ice and extracted with chloroform-methanol.
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