Bushinsky D A
Am J Physiol. 1987 Apr;252(4 Pt 2):F585-9. doi: 10.1152/ajprenal.1987.252.4.F585.
Bone mineral buffers protons during acute metabolic acidosis; whether parathyroid hormone (PTH) augments proton buffering is controversial. To determine whether PTH augments proton buffering by bone, we cultured neonatal mouse calvariae with or without PTH (10(-8) M) for 3 h in medium that was physiologically acid (pH approximately 7.20), neutral (pH approximately 7.40), or alkaline (pH approximately 7.60). Over the entire pH range studied there was less influx of protons into calvariae treated with PTH than into control calvariae, indicating that PTH does not augment but instead inhibits proton buffering by bone. To determine whether chronic exposure to PTH is necessary to augment proton buffering, calvariae were incubated with PTH for 24 h before a 3-h culture. Calcium efflux from calvariae exposed to PTH (10(-8) M) for 24 h exceeded that of controls. When these same calvariae were recultured for 3 h in fresh medium, PTH-treated and control calvariae behaved similarly, with net efflux of protons into acid, neutral, and alkaline media. Regardless of whether PTH is added at the time of exposure to acid medium or 24 h before calvariae cultured with PTH do not buffer protons to a greater extent than controls.
在急性代谢性酸中毒期间，骨矿物质可缓冲质子；甲状旁腺激素（PTH）是否增强质子缓冲作用存在争议。为了确定PTH是否通过骨增强质子缓冲作用，我们将新生小鼠颅骨在生理酸性（pH约7.20）、中性（pH约7.40）或碱性（pH约7.60）的培养基中，分别在有或无PTH（10⁻⁸ M）的情况下培养3小时。在所研究的整个pH范围内，与对照颅骨相比，用PTH处理的颅骨质子流入量更少，这表明PTH不会增强反而会抑制骨的质子缓冲作用。为了确定是否需要长期暴露于PTH才能增强质子缓冲作用，在进行3小时培养前，先将颅骨与PTH孵育24小时。暴露于PTH（10⁻⁸ M）24小时的颅骨钙流出量超过对照组。当将这些相同的颅骨在新鲜培养基中再培养3小时时，经PTH处理的颅骨和对照颅骨表现相似，质子向酸性、中性和碱性培养基中的净流出情况相同。无论在暴露于酸性培养基时添加PTH，还是在培养颅骨前24小时添加，经PTH处理的颅骨都不会比对照颅骨更有效地缓冲质子。
