Acetyl phosphate is hydrolyzed by the calcium ATPase of leaky sarcoplasmic reticulum vesicles from rabbit skeletal muscle with Km = 6.5 mM and kcat = 7.9 s-1 in the presence of 100 microM calcium (180 mM K+, 5 mM MgSO4, pH 7.0, 25 degrees C). In the absence of calcium, hydrolysis is 6% of the calcium-dependent rate at low and 24% at saturating concentrations of acetyl phosphate. Values of K0.5 ...

High postmenopausal endogenous estrogen concentrations are an important determinant of preservation of bone mass and reduced fracture in elderly women. Calcium supplementation can also reduce bone loss in these patients, suggesting an interaction between estrogen deficiency and calcium balance. Potential mechanisms of estrogen on calcium transport include direct effects on the bone, the kidney,...

The role of the parathyroid hormone in the regulation of calcium and phosphate metabolism has been recognized for many years (1). At the cellular level, the hormone is thought to regulate calcium and phosphate transport reactions. It is now known to (a) increase calcium reabsorption in the renal tubule (2, 3), (b) increase the transport of calcium across intestinal membranes (a, 5), (c) increas...

In this paper synthesis and characterization of a bioactive calcium phosphate glass-ceramic is presented, synthesized using a facile method. The glass-ceramic samples are synthesized with heat treating the parent glass at appropriate temperatures, where different calcium phosphate crystalline phases are grown in the parent glass samples during the heat treatment. The amounts of elements a...

In this study, calcium-phosphate (Ca-P) and graphene oxide (GO)/ calcium-phosphate (Ca-P) coatings were electrodeposited with different pulsed current densities on TiO2 nanotubes. Results showed that the co-electrodeposition rate in the presence of GO, especially at low current densities of 2 and 5 mA/cm2, significantly decreased. This might be due to the large size of GO sheets as compared to ...

INTRODUCTION: Composites of purified collagen and calcium phosphate salts have been widely used to produce osteoconductive scaffolds for fracture healing and spinal fusion. The effects of different calcium phosphate additives in a collagen scaffold was previously investigated in a rat model of ectopic bone formation induced by a mixture of bovine bone derived growth factors. It was found that o...

BACKGROUND Calcium is an essential cotherapy in osteoporosis treatment. The relative effectiveness of various calcium salts for this purpose is uncertain. Many older women with osteoporosis have phosphorus intakes of <70% of the Recommended Dietary Allowance. OBJECTIVE Our objective was to test the hypothesis that calcium phosphate would better support anabolic bone building than would calciu...

The calcium transport protein of the sarcoplasmic reticulum accepts inorganic phosphate rapidly when phosphorylation is initiated either by the addition of phosphate or magnesium ions to the calcium free protein. Phosphorylation proceeds much more slowly when it is initiated by the addition of the calcium chelatro ethyleneglycol-bis (beta-aminoethyl ether)-N,N'-tetraacetic acid (EGTA) to the ph...

Renal failure of 4 wk duration in rats led to parathyroid enlargement, increased bone resorption, and decreased tubular reabsorption of phosphate by the remnant kidney. The degree of hyperparathyroidism was influenced by each of the three dietary factors investigated. In the first study increasing calcium intake reduced the size of the parathyroids by increasing calcium and reducing phosphate a...

A single-dose, prospective, randomized, four-treatment, four-period crossover study was conducted to determine the acute effect of therapeutically equivalent doses of three commonly used phosphate binders on oral iron absorption. Twenty-three healthy subjects received 65 mg of elemental iron alone and with each phosphate binder (calcium carbonate 3000 mg, calcium acetate 2668 mg, or sevelamer H...