Osteoclasts and osteoblasts play an important role in bone remodeling, and their dysfunction can lead to a series of bone diseases, such as osteoporosis and osteoselerosis.Reeent studies have found that the active substances secreted by osteo¬blasts can regulate the recruitment, attachment, proliferation and differentiation of osteoclasts, thus affecting bone resorption.'Hie active substances derived from osteoclasts can also regulate the formation, survival, differentiation and mineralization of os¬ teoblasts and affect bone fonnation.In this paper, the active substances produced by osteoblasts and osteoclasts at present are summarized, and their functions are analyzed, so as to provide new ideas for dnjgs regulation of the dynamic balance between osteoblasts and osteoclasts.

Objective The mechanisms of docosahexaenoic acid (DHA) protecting the cardiovascular system have not yet been clarified. This study was to investigate the vasorelaxative effect of 13,14-epoxy docosapentaenoic acid (13,14-EpDPE) on coronary arterioles in normal rats and its action mechanisms.Methods We isolated coronary artery smooth muscle cells (CASMCs) from normal rats by enzyme digestion, examined the open probabilities of the large conductance calcium-activated potassium (BK) channels in inside-out single channel configuration in the presence of different concentrations (0, 1, 10 and 100 pmol/L) of 13,14-EpDPE, and recorded the BK currents with the patch clamp in whole cell configuration. Then we assessed the coronary arterial relaxation by measuring dilatory responses to 13,14-EpDPE in pre-contracted tissues with or without pre-treatment with iberiotoxin.Results In the presence of 0, 1, 10 and 100 pmol/L of 13,14-EpDPE, the open probabilities of the BK channels were 0.25±0.03, 0.34±0.03, 0.44±0.06 and 0.85±0.16 (n=6), respectively, significantly increased at 100 pmol/L as compared with 0, 1 and 10 pmol/L (P<0.05). The BK channels were activated by 13,14-EpDP in a concentration-dependent manner and its half-effect concentration was (15.94±1.21) pmol/L. The current density was increased from (58.27±16.35) to (95.94±23.00) pA/pF (P=0.002) after 10 pmol/L 13,14-EpDP perfusion when the stimulation voltage was 100 mV. 13,14-EpDPE dilated the isolated coronary arterioles in a dose-dependent manner, and its effects were abolished after pre-treatment with iberiotoxin (100 nM).Conclusion 13,14-EpDPE can dilate coronary arterioles by activating BK channels in CASMCs, which might be one of the mechanisms underlying its protective effect on the cardiovascular system.