Simulated microgravity reduces intracellular-free calcium concentration by inhibiting calcium channels in primary mouse osteoblasts.

Calcium homeostasis in osteoblasts plays fundamental roles in the physiology and pathology of bone tissue. Various types of mechanical stimuli promote osteogenesis and increase bone formation elicit increases in intracellular-free calcium concentration in osteoblasts. However, whether microgravity, a condition of mechanical unloading, exerts an influence on intracellular-free calcium concentration in osteoblasts or what mechanisms may underlie such an effect are unclear. Herein, we show that simulated microgravity reduces intracellular-free calcium concentration in primary mouse osteoblasts. In addition, simulated microgravity substantially suppresses the activities of L-type voltage-sensitive calcium channels, which selectively allow calcium to cross the plasma membrane from the extracellular space. Moreover, the functional expression of ryanodine receptors and inositol 1,4,5-trisphosphate receptors, which mediate the release of calcium from intracellular storage, decreased under simulated microgravity conditions. These results suggest that simulated microgravity substantially reduces intracellular-free calcium concentration through inhibition of calcium channels in primary mouse osteoblasts. Our study may provide a novel mechanism for microgravity-induced detrimental effects in osteoblasts, offering a new avenue to further investigate bone loss induced by mechanical unloading.

[Study on HPLC-DAD Fingerprint of Xiaoying Jiedu Decoction].

OBJECTIVE: Based on backtracking method, identification and quality evaluation of Xiaoying Jiedu Decoction (XYJDD) by HPLC fingerprint analysis were carried out. METHODS: HPLC-DAD fingerprint of XYJDD was conducted with Dikma Platisil ODS C18 column (250 mm x 4.6 mm, 5 µm) and gradient elution with the mobile phase consisting of acetonitrile-(0.1% phosphoric acid-0.1% triethylamine solution) at column temperature of 30 °C. On the basis of the established chromatographic pattern of XYJDD tracking backward to the corresponding crude herbal drugs in the formula and the attribution of most peaks in the XYJDD fingerprint can be figured out. RESULTS: 16 peaks of XYJDD HPLC fingerprint were assigned by parallel comparison with the fingerprint of the five corresponding crude drugs in the formula of Scutellariae Radix, Glycyrrhizae Radix et Rhizoma, Houttuyniae Herba, Aurantii Fructus, Arnebiae Radix. Four peaks can be identified with the chemical reference substances. CONCLUSION: The entirety of XYJDD HPLC fingerprint enhances the specialty for control and assessment of the product quality, and the backtracking experimental method can be expected to be applied in chromatographic fingerprinting analysis of complex Chinese patent medicine.