Bushinsky D A, Wolbach W, Sessler N E, Mogilevsky R, Levi-Setti R
Nephrology Unit, University of Rochester School of Medicine and Dentistry, New York.
J Bone Miner Res. 1993 Jan;8(1):93-102. doi: 10.1002/jbmr.5650080112.
Net calcium flux (JCa) from bone in vitro is pH dependent. When pH falls below 7.40, through a reduction in [HCO3-], there is both physicochemical and cell-mediated JCa. To characterize the physicochemical effect of acidosis on bone we inhibited the bone-resorbing cells (osteoclasts) with the specific inhibitor calcitonin and studied the effect of acidosis on JCa and bone ion composition using an analytic high-resolution scanning ion microprobe. Neonatal mouse calvariae were cultured for 48 h in physiologically neutral pH medium (Ntl, pH = 7.41, [HCO3-] = 25 nM) or in medium that modeled metabolic acidosis (Met, pH = 7.10, [HCO3-] = 12), each with or without calcitonin (CT, 3 x 10(-9) M). There was net calcium efflux in Ntl (JCa = 631 +/- 36 nmol per bone per 48 h), which increased in Met (1019 +/- 53, p < 0.01); CT inhibited JCa in Ntl (-54 +/- 11, p < 0.01 versus Ntl), which increased in Met (197 +/- 15, p < 0.01 versus Ntl + CT). In the presence of CT the increase in JCa in Met versus Ntl represents physiochemical bone dissolution. The Ntl bone surface (approximately 2 nm in depth) was rich in Na compared to Ca (Na/Ca = 11.9, count/s of detected secondary ions), which fell in Met (Na/Ca = 6.0, p < 0.05); CT caused a further reduction of Na/Ca (3.1, p < 0.01 versus Ntl and versus Met), which was not altered in Met (2.6, p < 0.05 versus Ntl + CT).(ABSTRACT TRUNCATED AT 250 WORDS)
体外骨骼的净钙通量（JCa）取决于pH值。当pH值降至7.40以下时，通过[HCO3-]的降低，会出现物理化学和细胞介导的JCa。为了表征酸中毒对骨骼的物理化学作用，我们用特异性抑制剂降钙素抑制骨吸收细胞（破骨细胞），并使用高分辨率分析扫描离子微探针研究酸中毒对JCa和骨离子组成的影响。将新生小鼠颅骨在生理中性pH培养基（Ntl，pH = 7.41，[HCO3-] = 25 nM）或模拟代谢性酸中毒的培养基（Met，pH = 7.10，[HCO3-] = 12）中培养48小时，每种培养基添加或不添加降钙素（CT，3×10（-9）M）。Ntl中有净钙外流（JCa = 每块骨每48小时631±36 nmol），在Met中增加（1019±53，p < 0.01）；CT在Ntl中抑制JCa（-54±11，与Ntl相比p < 0.01），在Met中增加（197±15，与Ntl + CT相比p < 0.01）。在CT存在的情况下，Met与Ntl相比JCa的增加代表物理化学性骨溶解。与Ca相比，Ntl骨表面（深度约2 nm）富含Na（Na/Ca = 11.9，检测到的二次离子计数/秒），在Met中降低（Na/Ca = 6.0，p < 0.05）；CT导致Na/Ca进一步降低（3.1，与Ntl和Met相比p < 0.01），在Met中未改变（2.6，与Ntl + CT相比p < 0.05）。（摘要截断于250字）
